OpenShift Container Platform 3.3

Using Images

OpenShift Container Platform 3.3 Guide to Using Images

Red Hat OpenShift Documentation Team

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Abstract

Use these topics to find out what different S2I (Source-to-Image), database and Docker images are available for OpenShift Container Platform 3.3 users.

Chapter 1. Overview

Use these topics to discover the different S2I (Source-to-Image), database, and other container images that are available for OpenShift Container Platform users.

Red Hat’s official container images are provided in the Red Hat Registry at registry.access.redhat.com. OpenShift Container Platform’s supported S2I, database, and Jenkins images are provided in the openshift3 repository in the Red Hat Registry. For example, registry.access.redhat.com/openshift3/nodejs-010-rhel7 for the Node.js image.

The xPaaS middleware images are provided in their respective product repositories on the Red Hat Registry, but suffixed with a -openshift. For example, registry.access.redhat.com/jboss-eap-6/eap64-openshift for the JBoss EAP image.

Chapter 2. Source-to-Image (S2I)

Overview

This topic group includes information on the different S2I (Source-to-Image) supported images available for OpenShift Container Platform users.

.NET Core

Benefits of Using .NET Core

.NET Core is a general purpose development platform featuring automatic memory management and modern programming languages. It allows users to build high quality applications efficiently. .NET Core is available on Red Hat Enterprise Linux (RHEL 7) and OpenShift Container Platform via certified containers. .NET Core offers:

The ability to follow a microservices-based approach, where some components are built with .NET and others with Java, but all can run on a common, supported platform in Red Hat Enterprise Linux and OpenShift Container Platform.

The capacity to more easily develop new .NET Core workloads on Windows; customers are able to deploy and run on either Red Hat Enterprise Linux or Windows Server.

A heterogeneous data center, where the underlying infrastructure is capable of running .NET applications without having to rely solely on Windows Server.

Access to many of the popular development frameworks such as .NET, Java, Ruby, and Python from within OpenShift Container Platform.

Supported Versions

.NET Core version 1.0

Supported on Red Hat Enterprise Linux (RHEL) 7 and OpenShift Container Platform versions 3.3 and later

Images

Image stream definitions for the .NET Core on RHEL S2I image are now added during OpenShift Container Platform installations.

The RHEL 7 images are available through Red Hat’s subscription registry using:

$ docker pull registry.access.redhat.com/dotnet/dotnetcore-10-rhel7

To use these images, you can either access them directly from these image registries, or push them into your OpenShift Container Platform Docker registry. Additionally, you can create an image stream that points to the image, either in your Docker registry or at the external location. Your OpenShift Container Platform resources can then reference the image stream definition.

Configuration

The .NET Core image currently does not support any environment variables. No configuration is necessary.

Quickly Deploying Applications from .NET Core Source

Important

The .NET image stream must first be installed. If you ran a standard installation, the image stream will be present.

An image can be used to build an application by running oc new-app against a sample repository:

$ oc new-app https://github.com/redhat-developer/s2i-dotnetcore --context-dir=1.0/test/asp-net-hello-world

Note

The oc new-app command can detect .NET Core source starting in OpenShift Container Platform 3.3.

Node.js

Overview

OpenShift Container Platform provides S2I enabled Node.js images for building and running Node.js applications. The Node.js S2I builder image assembles your application source with any required dependencies to create a new image containing your Node.js application. This resulting image can be run either by OpenShift Container Platform or by Docker.

Versions

Currently, OpenShift Container Platform provides versions 0.10 and 4 of Node.js.

Images

These images come in two flavors, depending on your needs:

RHEL 7

CentOS 7

RHEL 7 Based Image

The RHEL 7 images are available through Red Hat’s subscription registry using:

$ docker pull registry.access.redhat.com/openshift3/nodejs-010-rhel7
$ docker pull registry.access.redhat.com/rhscl/nodejs-4-rhel7

CentOS 7 Based Image

This image is available on DockerHub. To download it:

$ docker pull openshift/nodejs-010-centos7

To use these images, you can either access them directly from these image registries, or push them into your OpenShift Container Platform Docker registry. Additionally, you can create an image stream that points to the image, either in your Docker registry or at the external location. Your OpenShift Container Platform resources can then reference the ImageStream. You can find example image stream definitions for all the provided OpenShift Container Platform images.

Configuration

The Node.js image supports a number of environment variables, which can be set to control the configuration and behavior of the Node.js runtime.

To set these environment variables as part of your image, you can place them into a .s2i/environment file inside your source code repository, or define them in the environment section of the build configuration’s sourceStrategy definition.

You can also set environment variables to be used with an existing image when creating new applications, or by updating environment variables for existing objects such as deployment configurations.

Note

Environment variables that control build behavior must be set as part of the s2i build configuration or in the .s2i/environment file to make them available to the build steps.

Table 2.1. Development Mode Environment Variables

Variable name
Description

DEV_MODE

When set to true, enables hot deploy and opens the debug port. Additionally, indicates to tooling that the image is in development mode. Default is false.

DEBUG_PORT

The debug port. Only valid if DEV_MODE is set to true. Default is 5858.

NPM_MIRROR

The custom NPM registry mirror URL. All NPM packages will be downloaded from the mirror link during the build process.

Hot Deploying

Hot deployment allows you to quickly make and deploy changes to your application without having to generate a new S2I build. In order to immediately pick up changes made in your application source code, you must run your built image with the DEV_MODE=true environment variable.

You can set new environment variables when creating new applications, or updating environment variables for existing objects.

Warning

Only use the DEV_MODE=true environment variable while developing or debugging. Using this in your production environment is not recommended.

To change the source code of a running pod, open a remote shell into the container:

$ oc rsh <pod_id>

Entering into a running container changes your current directory to /opt/app-root/src, where the source code is located.

Perl

Overview

OpenShift Container Platform provides S2I enabled Perl images for building and running Perl applications. The Perl S2I builder image assembles your application source with any required dependencies to create a new image containing your Perl application. This resulting image can be run either by OpenShift Container Platform or by Docker.

Versions

Currently, OpenShift Container Platform supports version 5.16 of Perl.

Images

This image comes in two flavors, depending on your needs:

RHEL 7

CentOS 7

RHEL 7 Based Image

The RHEL 7 image is available through Red Hat’s subscription registry using:

$ docker pull registry.access.redhat.com/openshift3/perl-516-rhel7

CentOS 7 Based Image

This image is available on DockerHub. To download it:

$ docker pull openshift/perl-516-centos7

To use these images, you can either access them directly from these image registries, or push them into your OpenShift Container Platform Docker registry. Additionally, you can create an image stream that points to the image, either in your Docker registry or at the external location. Your OpenShift Container Platformt resources can then reference the ImageStream. You can find example image stream definitions for all the provided OpenShift Container Platform images.

Configuration

The Perl image supports a number of environment variables which can be set to control the configuration and behavior of the Perl runtime.

To set these environment variables as part of your image, you can place them into a .s2i/environment file inside your source code repository, or define them in the environment section of the build configuration’s sourceStrategy definition.

You can also set environment variables to be used with an existing image when creating new applications, or by updating environment variables for existing objects such as deployment configurations.

Note

Environment variables that control build behavior must be set as part of the s2i build configuration or in the .s2i/environment file to make them available to the build steps.

Table 2.2. Perl Environment Variables

Variable name
Description

ENABLE_CPAN_TEST

When set to true, this variable installs all the cpan modules and runs their tests. By default, the testing of the modules is turned off.

CPAN_MIRROR

This variable specifies a mirror URL which cpanminus uses to install dependencies. By default, this URL is not specified.

PERL_APACHE2_RELOAD

Set this to true to enable automatic reloading of modified Perl modules. By default, automatic reloading is turned off.

HTTPD_START_SERVERS

The StartServers directive sets the number of child server processes created on startup. Default is 8.

HTTPD_MAX_REQUEST_WORKERS

Number of simultaneous requests that will be handled by Apache. The default is 256, but it will be automatically lowered if memory is limited.

Accessing Logs

Access logs are streamed to standard output and as such they can be viewed using the oc logs command. Error logs are stored in the /tmp/error_log file, which can be viewed using the oc rsh command to access the container.

Hot Deploying

Hot deployment allows you to quickly make and deploy changes to your application without having to generate a new S2I build. To enable hot deployment in this image, you must set the PERL_APACHE2_RELOAD environment variable to true. For example, see the oc new-app command. You can use the oc set env command to update environment variables of existing objects.

Warning

You should only use this option while developing or debugging; it is not recommended to turn this on in your production environment.

To change your source code in a running pod, use the oc rsh command to enter the container:

$ oc rsh <pod_id>

After you enter into the running container, your current directory is set to /opt/app-root/src, where the source code is located.

PHP

Overview

OpenShift Container Platform provides S2I enabled PHP images for building and running PHP applications. The PHP S2I builder image assembles your application source with any required dependencies to create a new image containing your PHP application. This resulting image can be run either by OpenShift Container Platform or by Docker.

Versions

Currently, OpenShift Container Platform provides version 5.5 and 5.6 of PHP.

Images

This image comes in two flavors, depending on your needs:

RHEL 7

CentOS 7

RHEL 7 Based Image

The RHEL 7 image is available through Red Hat’s subscription registry using:

$ docker pull registry.access.redhat.com/openshift3/php-55-rhel7

CentOS 7 Based Image

This image is available on DockerHub. To download it:

$ docker pull openshift/php-55-centos7

To use these images, you can either access them directly from these image registries, or push them into your OpenShift Container Platform Docker registry. Additionally, you can create an image stream that points to the image, either in your Docker registry or at the external location. Your OpenShift Container Platform resources can then reference the image stream.

You can find example image stream definitions for all the provided OpenShift Container Platform images.

Configuration

The PHP image supports a number of environment variables which can be set to control the configuration and behavior of the PHP runtime.

To set these environment variables as part of your image, you can place them into a .s2i/environment file inside your source code repository, or define them in the environment section of the build configuration’s sourceStrategy definition.

You can also set environment variables to be used with an existing image when creating new applications, or by updating environment variables for existing objects such as deployment configurations.

Note

Environment variables that control build behavior must be set as part of the s2i build configuration or in the .s2i/environment file to make them available to the build steps.

The following environment variables set their equivalent property value in the php.ini file:

Table 2.3. PHP Environment Variables

Variable Name
Description
Default

ERROR_REPORTING

Informs PHP of the errors, warnings, and notices for which you would like it to take action.

E_ALL & ~E_NOTICE

DISPLAY_ERRORS

Controls if and where PHP outputs errors, notices, and warnings.

ON

DISPLAY_STARTUP_ERRORS

Causes any display errors that occur during PHP’s startup sequence to be handled separately from display errors.

OFF

TRACK_ERRORS

Stores the last error/warning message in $php_errormsg (boolean).

OFF

HTML_ERRORS

Links errors to documentation that is related to the error.

ON

INCLUDE_PATH

Path for PHP source files.

.:/opt/openshift/src:/opt/rh/php55/root/usr/share/pear

SESSION_PATH

Location for session data files.

/tmp/sessions

DOCUMENTROOT

Path that defines the document root for your application (for example, /public).

/

The following environment variable sets its equivalent property value in the opcache.ini file:

Table 2.4. Additional PHP settings

Variable Name
Description
Default

OPCACHE_MEMORY_CONSUMPTION

The OPcache shared memory storage size.

16M

OPCACHE_REVALIDATE_FREQ

How often to check script time stamps for updates, in seconds. 0 results in OPcache checking for updates on every request.

2

You can also override the entire directory used to load the PHP configuration by setting:

Table 2.5. Additional PHP settings

Variable Name
Description

PHPRC

Sets the path to the php.ini file.

PHP_INI_SCAN_DIR

Path to scan for additional .ini configuration files

You can use a custom composer repository mirror URL to download packages instead of the default 'packagist.org':

Table 2.6. Composer Environment Variables

Variable Name
Description
COMPOSER_MIRROR

Apache Configuration

If the DocumentRoot of the application is nested in the source directory /opt/openshift/src, you can provide your own .htaccess file to override the default Apache behavior and specify how application requests should be handled. The .htaccess file must be located at the root of the application source.

Accessing Logs

Access logs are streamed to standard out and as such they can be viewed using the oc logs command. Error logs are stored in the /tmp/error_log file, which can be viewed using the oc rsh command to access the container.

Hot Deploying

Hot deployment allows you to quickly make and deploy changes to your application without having to generate a new S2I build. In order to immediately pick up changes made in your application source code, you must run your built image with the OPCACHE_REVALIDATE_FREQ=0 environment variable.

For example, see the oc new-app command. You can use the oc env command to update environment variables of existing objects.

Warning

You should only use this option while developing or debugging; it is not recommended to turn this on in your production environment.

To change your source code in a running pod, use the oc rsh command to enter the container:

$ oc rsh <pod_id>

After you enter into the running container, your current directory is set to /opt/app-root/src, where the source code is located.

Python

Overview

OpenShift Container Platform provides S2I enabled Python images for building and running Python applications. The Python S2I builder image assembles your application source with any required dependencies to create a new image containing your Python application. This resulting image can be run either by OpenShift Container Platform or by Docker.

Versions

Currently, OpenShift Container Platform provides versions 2.7, 3.3, 3.4, and 3.5 of Python.

Images

These images come in two flavors, depending on your needs:

RHEL 7

CentOS 7

RHEL 7 Based Image

The RHEL 7 images are available through Red Hat’s subscription registry using:

$ docker pull registry.access.redhat.com/openshift3/python-33-rhel7
$ docker pull registry.access.redhat.com/rhscl/python-35-rhel7

CentOS 7 Based Image

These images are available on DockerHub. To download them:

$ docker pull openshift/python-33-centos7
$ docker pull centos/python-35-centos7

To use these images, you can either access them directly from these image registries, or push them into your OpenShift Container Platform Docker registry. Additionally, you can create an image stream that points to the image, either in your Docker registry or at the external location. Your OpenShift Container Platform resources can then reference the ImageStream. You can find example image stream definitions for all the provided OpenShift Container Platform images.

Configuration

The Python image supports a number of environment variables which can be set to control the configuration and behavior of the Python runtime.

To set these environment variables as part of your image, you can place them into a .s2i/environment file inside your source code repository, or define them in the environment section of the build configuration’s sourceStrategy definition.

You can also set environment variables to be used with an existing image when creating new applications, or by updating environment variables for existing objects such as deployment configurations.

Note

Environment variables that control build behavior must be set as part of the s2i build configuration or in the .s2i/environment file to make them available to the build steps.

Table 2.7. Python Environment Variables

Variable name
Description

APP_FILE

This variable specifies the file name passed to the python interpreter which is responsible for launching the application. This variable is set to app.py by default.

APP_MODULE

This variable specifies the WSGI callable. It follows the pattern $(MODULE_NAME):$(VARIABLE_NAME), where the module name is a full dotted path and the variable name refers to a function inside the specified module. If you use setup.py for installing the application, then the module name can be read from that file and the variable defaults to application. There is an example setup-test-app available.

APP_CONFIG

This variable indicates the path to a valid Python file with a gunicorn configuration.

DISABLE_COLLECTSTATIC

Set it to a nonempty value to inhibit the execution of manage.py collectstatic during the build. Only affects Django projects.

DISABLE_MIGRATE

Set it to a nonempty value to inhibit the execution of manage.py migrate when the produced image is run. Only affects Django projects.

PIP_INDEX_URL

Set this variable to use a custom index URL or mirror to download required packages during build process. This only affects packages listed in the requirements.txt file.

WEB_CONCURRENCY

Set this to change the default setting for the number of workers. By default, this is set to the number of available cores times 4.

Hot Deploying

Hot deployment allows you to quickly make and deploy changes to your application without having to generate a new S2I build. If you are using Django, hot deployment works out of the box.

To enable hot deployment while using Gunicorn, ensure you have a Gunicorn configuration file inside your repository with the reload option set to true. Specify your configuration file using the APP_CONFIG environment variable. For example, see the oc new-app command. You can use the oc set env command to update environment variables of existing objects.

Warning

You should only use this option while developing or debugging; it is not recommended to turn this on in your production environment.

To change your source code in a running pod, use the oc rsh command to enter the container:

$ oc rsh <pod_id>

After you enter into the running container, your current directory is set to /opt/app-root/src, where the source code is located.

Ruby

Overview

OpenShift Container Platform provides S2I enabled Ruby images for building and running Ruby applications. The Ruby S2I builder image assembles your application source with any required dependencies to create a new image containing your Ruby application. This resulting image can be run either by OpenShift Container Platform or by Docker.

Versions

Currently, OpenShift Container Platform provides versions 2.0, 2.2, and 2.3 of Ruby.

Images

These images come in two flavors, depending on your needs:

RHEL 7

CentOS 7

RHEL 7 Based Image

The RHEL 7 images are available through Red Hat’s subscription registry using:

$ docker pull registry.access.redhat.com/openshift3/ruby-20-rhel7
$ docker pull registry.access.redhat.com/rhscl/ruby-23-rhel7

CentOS 7 Based Image

These images are available on DockerHub. To download them:

$ docker pull openshift/ruby-20-centos7
$ docker pull centos/ruby-23-centos7

To use these images, you can either access them directly from these image registries, or push them into your OpenShift Container Platform Docker registry. Additionally, you can create an image stream that points to the image, either in your Docker registry or at the external location. Your OpenShift Container Platform resources can then reference the ImageStream. You can find example image stream definitions for all the provided OpenShift Container Platform images.

Configuration

The Ruby image supports a number of environment variables which can be set to control the configuration and behavior of the Ruby runtime.

To set these environment variables as part of your image, you can place them into a .s2i/environment file inside your source code repository, or define them in the environment section of the build configuration’s sourceStrategy definition.

You can also set environment variables to be used with an existing image when creating new applications, or by updating environment variables for existing objects such as deployment configurations.

Note

Environment variables that control build behavior must be set as part of the s2i build configuration or in the .s2i/environment file to make them available to the build steps.

Table 2.8. Ruby Environment Variables

Variable name
Description

RACK_ENV

This variable specifies the environment within which the Ruby application is deployed; for example, production, development, or test. Each level has different behavior in terms of logging verbosity, error pages, and ruby gem installation. The application assets are only compiled if RACK_ENV is set to production; the default value is production.

RAILS_ENV

This variable specifies the environment within which the Ruby on Rails application is deployed; for example, production, development, or test. Each level has different behavior in terms of logging verbosity, error pages, and ruby gem installation. The application assets are only compiled if RAILS_ENV is set to production. This variable is set to ${RACK_ENV} by default.

DISABLE_ASSET_COMPILATION

When set to true, this variable disables the process of asset compilation. Asset compilation only happens when the application runs in a production environment. Therefore, you can use this variable when assets have already been compiled.

PUMA_MIN_THREADS, PUMA_MAX_THREADS

This variable indicates the minimum and maximum number of threads that will be available in Puma's thread pool.

PUMA_WORKERS

This variable indicates the number of worker processes to be launched in Puma’s clustered mode (when Puma runs more than two processes). If not explicitly set, the default behavior sets PUMA_WORKERS to a value that is appropriate for the memory available to the container and the number of cores on the host.

RUBYGEM_MIRROR

Set this variable to use a custom RubyGems mirror URL to download required gem packages during the build process. Note: This environment variable is only available for Ruby 2.2+ images.

Hot Deploying

Hot deployment allows you to quickly make and deploy changes to your application without having to generate a new S2I build. The method for enabling hot deployment in this image differs based on the application type.

Ruby on Rails Applications

For Ruby on Rails application, run the built Rails application with the RAILS_ENV=development environment variable passed to the running pod. For an existing deployment configuration, you can use the oc set env command:

$ oc set env dc/rails-app RAILS_ENV=development

Other Types of Ruby Applications (Sinatra, Padrino, etc.)

For other types of Ruby applications, your application must be built with a gem that can reload the server every time a change to the source code is made inside the running container. Those gems are:

Shotgun

Rerun

Rack-livereload

In order to be able to run your application in development mode, you must modify the S2I run script so that the web server is launched by the chosen gem, which checks for changes in the source code.

After you build your application image with your version of the S2I run script, run the image with the RACK_ENV=development environment variable. For example, see the oc new-app command. You can use the oc set env command to update environment variables of existing objects.

Warning

You should only use this option while developing or debugging; it is not recommended to turn this on in your production environment.

To change your source code in a running pod, use the oc rsh command to enter the container:

$ oc rsh <pod_id>

After you enter into the running container, your current directory is set to /opt/app-root/src, where the source code is located.

Chapter 3. Database Images

Overview

This topic group includes information on the different database images available for OpenShift Container Platform users.

Note

Enabling clustering for database images is currently in Technology Preview and not intended for production use.

MySQL

Overview

OpenShift Container Platform provides a container image for running MySQL. This image can provide database services based on username, password, and database name settings provided via configuration.

Versions

Currently, OpenShift Container Platform provides version 5.5 and 5.6 of MySQL.

Images

This image comes in two flavors, depending on your needs:

RHEL 7

CentOS 7

RHEL 7 Based Image

The RHEL 7 image is available through Red Hat’s subscription registry via:

$ docker pull registry.access.redhat.com/openshift3/mysql-55-rhel7

CentOS 7 Based Image

This image is available on DockerHub. To download it:

$ docker pull openshift/mysql-55-centos7

To use these images, you can either access them directly from these registries or push them into your OpenShift Container Platform Docker registry. Additionally, you can create an ImageStream that points to the image, either in your Docker registry or at the external location. Your OpenShift Container Platform resources can then reference the ImageStream. You can find example ImageStream definitions for all the provided OpenShift Container Platform images.

Configuration and Usage

Initializing the Database

The first time you use the shared volume, the database is created along with the database administrator user and the MySQL root user (if you specify the MYSQL_ROOT_PASSWORD environment variable). Afterwards, the MySQL daemon starts up. If you are re-attaching the volume to another container, then the database, database user, and the administrator user are not created, and the MySQL daemon starts.

The following command creates a new database pod with MySQL running in a container:

$ oc new-app -e \
    MYSQL_USER=<username>,MYSQL_PASSWORD=<password>,MYSQL_DATABASE=<database_name> \
    registry.access.redhat.com/openshift3/mysql-55-rhel7

Running MySQL Commands in Containers

OpenShift Container Platform uses Software Collections (SCLs) to install and launch MySQL. If you want to execute a MySQL command inside of a running container (for debugging), you must invoke it using bash.

To do so, first identify the name of the pod. For example, you can view the list of pods in your current project:

$ oc get pods

Then, open a remote shell session to the pod:

$ oc rsh <pod>

When you enter the container, the required SCL is automatically enabled.

You can now run the mysql command from the bash shell to start a MySQL interactive session and perform normal MySQL operations. For example, to authenticate as the database user:

bash-4.2$ mysql -u $MYSQL_USER -p$MYSQL_PASSWORD -h $HOSTNAME $MYSQL_DATABASE
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.5.37 MySQL Community Server (GPL)
...
mysql>

When you are finished, enter quit or exit to leave the MySQL session.

Environment Variables

The MySQL user name, password, and database name must be configured with the following environment variables:

Table 3.1. MySQL Environment Variables

Variable Name
Description

MYSQL_USER

Specifies the user name for the database user that is created for use by your application.

MYSQL_PASSWORD

Password for the MYSQL_USER.

MYSQL_DATABASE

Name of the database to which MYSQL_USER has full rights.

MYSQL_ROOT_PASSWORD

Optional password for the root user. If this is not set, then remote login to the root account is not possible. Local connections from within the container are always permitted without a password.

MYSQL_SERVICE_HOST

Service host variable automatically created by Kubernetes.

MYSQL_SERVICE_PORT

Service port variable automatically created by Kubernetes.

Warning

You must specify the user name, password, and database name. If you do not specify all three, the pod will fail to start and OpenShift Container Platform will continuously try to restart it.

MySQL settings can be configured with the following environment variables:

Table 3.2. Additional MySQL Settings

Variable Name
Description
Default

MYSQL_LOWER_CASE_TABLE_NAMES

Sets how the table names are stored and compared.

0

MYSQL_MAX_CONNECTIONS

The maximum permitted number of simultaneous client connections.

151

MYSQL_MAX_ALLOWED_PACKET

The maximum size of one packet or any generated/intermediate string.

200M

MYSQL_FT_MIN_WORD_LEN

The minimum length of the word to be included in a FULLTEXT index.

4

MYSQL_FT_MAX_WORD_LEN

The maximum length of the word to be included in a FULLTEXT index.

20

MYSQL_AIO

Controls the innodb_use_native_aio setting value if the native AIO is broken.

1

MYSQL_TABLE_OPEN_CACHE

The number of open tables for all threads.

400

MYSQL_KEY_BUFFER_SIZE

The size of the buffer used for index blocks.

32M (or 10% of available memory)

MYSQL_SORT_BUFFER_SIZE

The size of the buffer used for sorting.

256K

MYSQL_READ_BUFFER_SIZE

The size of the buffer used for a sequential scan.

8M (or 5% of available memory)

MYSQL_INNODB_BUFFER_POOL_SIZE

The size of the buffer pool where InnoDB caches table and index data.

32M (or 50% of available memory)

MYSQL_INNODB_LOG_FILE_SIZE

The size of each log file in a log group.

8M (or 15% of available memory)

MYSQL_INNODB_LOG_BUFFER_SIZE

The size of the buffer that InnoDB uses to write to the log files on disk.

8M (or 15% of available memory)

Some of the memory-related parameters have two default values. The fixed value is used when a container does not have memory limits assigned. The other value is calculated dynamically during a container’s startup based on available memory.

Volume Mount Points

The MySQL image can be run with mounted volumes to enable persistent storage for the database:

/var/lib/mysql/data - This is the data directory where MySQL stores database files.

Changing Passwords

Passwords are part of the image configuration, therefore the only supported method to change passwords for the database user (MYSQL_USER) and root user is by changing the environment variables MYSQL_PASSWORD and MYSQL_ROOT_PASSWORD, respectively.

You can view the current passwords by viewing the pod or deployment configuration in the web console or by listing the environment variables with the CLI:

$ oc set env pod <pod_name> --list

Whenever MYSQL_ROOT_PASSWORD is set, it enables remote access for the root user with the given password, and whenever it is unset, remote access for the root user is disabled. This does not affect the regular user MYSQL_USER, who always has remote access. This also does not affect local access by the root user, who can always log in without a password in localhost.

Changing database passwords through SQL statements or any way other than through the environment variables aforementioned causes a mismatch between the values stored in the variables and the actual passwords. Whenever a database container starts, it resets the passwords to the values stored in the environment variables.

To change these passwords, update one or both of the desired environment variables for the related deployment configuration(s) using the oc set env command. If multiple deployment configurations utilize these environment variables, for example in the case of an application created from a template, you must update the variables on each deployment configuration so that the passwords are in sync everywhere. This can be done all in the same command:

$ oc set env dc <dc_name> [<dc_name_2> ...] \
  MYSQL_PASSWORD=<new_password> \
  MYSQL_ROOT_PASSWORD=<new_root_password>

Important

Depending on your application, there may be other environment variables for passwords in other parts of the application that should also be updated to match. For example, there could be a more generic DATABASE_USER variable in a front-end pod that should match the database user’s password. Ensure that passwords are in sync for all required environment variables per your application, otherwise your pods may fail to redeploy when triggered.

Updating the environment variables triggers the redeployment of the database server if you have a configuration change trigger. Otherwise, you must manually start a new deployment in order to apply the password changes.

To verify that new passwords are in effect, first open a remote shell session to the running MySQL pod:

$ oc rsh <pod>

From the bash shell, verify the database user’s new password:

bash-4.2$ mysql -u $MYSQL_USER -p<new_password> -h $HOSTNAME $MYSQL_DATABASE -te "SELECT * FROM (SELECT database()) db CROSS JOIN (SELECT user()) u"

If the password was changed correctly, you should see a table like this:

+------------+---------------------+
| database() | user()              |
+------------+---------------------+
| sampledb   | user0PG@172.17.42.1 |
+------------+---------------------+

To verify the root user’s new password:

bash-4.2$ mysql -u root -p<new_root_password> -h $HOSTNAME $MYSQL_DATABASE -te "SELECT * FROM (SELECT database()) db CROSS JOIN (SELECT user()) u"

If the password was changed correctly, you should see a table like this:

+------------+------------------+
| database() | user()           |
+------------+------------------+
| sampledb   | root@172.17.42.1 |
+------------+------------------+

Creating a Database Service from a Template

OpenShift Container Platform provides a template to make creating a new database service easy. The template provides parameter fields to define all the mandatory environment variables (user, password, database name, etc) with predefined defaults including auto-generation of password values. It will also define both a deployment configuration and a service.

The MySQL templates should have been registered in the default openshift project by your cluster administrator during the initial cluster setup. See Loading the Default Image Streams and Templates for more details, if required.

There are two templates available:

mysql-ephemeral is for development or testing purposes only because it uses ephemeral storage for the database content. This means that if the database pod is restarted for any reason, such as the pod being moved to another node or the deployment configuration being updated and triggering a redeploy, all data will be lost.

mysql-persistent uses a persistent volume store for the database data which means the data will survive a pod restart. Using persistent volumes requires a persistent volume pool be defined in the OpenShift Container Platform deployment. Cluster administrator instructions for setting up the pool are located here.

You can find instructions for instantiating templates by following these instructions.

Once you have instantiated the service, you can copy the user name, password, and database name environment variables into a deployment configuration for another component that intends to access the database. That component can then access the database via the service that was defined.

Using MySQL Replication

Note

Enabling clustering for database images is currently in Technology Preview and not intended for production use.

Red Hat provides a proof-of-concept template for MySQL master-slave replication (clustering); you can obtain the example template from GitHub.

To upload the example template into the current project’s template library:

$ oc create -f \
    https://raw.githubusercontent.com/openshift/mysql/master/5.5/examples/replica/mysql_replica.json

The following sections detail the objects defined in the example template and describe how they work together to start a cluster of MySQL servers implementing master-slave replication. This is the recommended replication strategy for MySQL.

Creating the Deployment Configuration for the MySQL Master

To set up MySQL replication, a deployment configuration is defined in the example template that defines a replication controller. For MySQL master-slave replication, two deployment configurations are needed. One deployment configuration defines the MySQL master server and second the MySQL slave servers.

To tell a MySQL server to act as the master, the command field in the container’s definition in the deployment configuration must be set to run-mysqld-master. This script acts as an alternative entrypoint for the MySQL image and configures the MySQL server to run as the master in replication.

MySQL replication requires a special user that relays data between the master and slaves. The following environment variables are defined in the template for this purpose:

Variable Name
Description
Default

MYSQL_MASTER_USER

The user name of the replication user

master

MYSQL_MASTER_PASSWORD

The password for the replication user

generated

Example 3.1. MySQL Master Deployment Configuration Object Definition in the Example Template

kind: "DeploymentConfig"
apiVersion: "v1"
metadata:
  name: "mysql-master"
spec:
  strategy:
    type: "Recreate"
  triggers:
    - type: "ConfigChange"
  replicas: 1
  selector:
    name: "mysql-master"
  template:
    metadata:
      labels:
        name: "mysql-master"
    spec:
      volumes:
        - name: "mysql-master-data"
          persistentVolumeClaim:
            claimName: "mysql-master"
      containers:
        - name: "server"
          image: "openshift/mysql-55-centos7"
          command:
            - "run-mysqld-master"
          ports:
            - containerPort: 3306
              protocol: "TCP"
          env:
            - name: "MYSQL_MASTER_USER"
              value: "${MYSQL_MASTER_USER}"
            - name: "MYSQL_MASTER_PASSWORD"
              value: "${MYSQL_MASTER_PASSWORD}"
            - name: "MYSQL_USER"
              value: "${MYSQL_USER}"
            - name: "MYSQL_PASSWORD"
              value: "${MYSQL_PASSWORD}"
            - name: "MYSQL_DATABASE"
              value: "${MYSQL_DATABASE}"
            - name: "MYSQL_ROOT_PASSWORD"
              value: "${MYSQL_ROOT_PASSWORD}"
          volumeMounts:
            - name: "mysql-master-data"
              mountPath: "/var/lib/mysql/data"
          resources: {}
          terminationMessagePath: "/dev/termination-log"
          imagePullPolicy: "IfNotPresent"
          securityContext:
            capabilities: {}
            privileged: false
      restartPolicy: "Always"
      dnsPolicy: "ClusterFirst"

Since we claimed a persistent volume in this deployment configuration to have all data persisted for the MySQL master server, you must ask your cluster administrator to create a persistent volume that you can claim the storage from.

After the deployment configuration is created and the pod with MySQL master server is started, it will create the database defined by MYSQL_DATABASE and configure the server to replicate this database to slaves.

The example provided defines only one replica of the MySQL master server. This causes OpenShift Container Platformto start only one instance of the server. Multiple instances (multi-master) is not supported and therefore you can not scale this replication controller.

To replicate the database created by the MySQL master, a deployment configuration is defined in the template. This deployment configuration creates a replication controller that launches the MySQL image with the command field set to run-mysqld-slave. This alternative entrypoints skips the initialization of the database and configures the MySQL server to connect to the mysql-master service, which is also defined in example template.

Example 3.2. MySQL Slave Deployment Configuration Object Definition in the Example Template

kind: "DeploymentConfig"
apiVersion: "v1"
metadata:
  name: "mysql-slave"
spec:
  strategy:
    type: "Recreate"
  triggers:
    - type: "ConfigChange"
  replicas: 1
  selector:
    name: "mysql-slave"
  template:
    metadata:
      labels:
        name: "mysql-slave"
    spec:
      containers:
        - name: "server"
          image: "openshift/mysql-55-centos7"
          command:
            - "run-mysqld-slave"
          ports:
            - containerPort: 3306
              protocol: "TCP"
          env:
            - name: "MYSQL_MASTER_USER"
              value: "${MYSQL_MASTER_USER}"
            - name: "MYSQL_MASTER_PASSWORD"
              value: "${MYSQL_MASTER_PASSWORD}"
            - name: "MYSQL_DATABASE"
              value: "${MYSQL_DATABASE}"
          resources: {}
          terminationMessagePath: "/dev/termination-log"
          imagePullPolicy: "IfNotPresent"
          securityContext:
            capabilities: {}
            privileged: false
      restartPolicy: "Always"
      dnsPolicy: "ClusterFirst"

This example deployment configuration starts the replication controller with the initial number of replicas set to 1. You can scale this replication controller in both directions, up to the resources capacity of your account.

Creating a Headless Service

The pods created by the MySQL slave replication controller must reach the MySQL master server in order to register for replication. The example template defines a headless service named mysql-master for this purpose. This service is not used only for replication, but the clients can also send the queries to mysql-master:3306 as the MySQL host.

To have a headless service, the portalIP parameter in the service definition is set to None. Then you can use a DNS query to get a list of the pod IP addresses that represents the current endpoints for this service.

Example 3.3. Headless Service Object Definition in the Example Template

kind: "Service"
apiVersion: "v1"
metadata:
  name: "mysql-master"
  labels:
    name: "mysql-master"
spec:
  ports:
    - protocol: "TCP"
      port: 3306
      targetPort: 3306
      nodePort: 0
  selector:
    name: "mysql-master"
  portalIP: "None"
  type: "ClusterIP"
  sessionAffinity: "None"
status:
  loadBalancer: {}

Scaling the MySQL Slaves

To increase the number of members in the cluster:

$ oc scale rc mysql-slave-1 --replicas=<number>

This tells the replication controller to create a new MySQL slave pod. When a new slave is created, the slave entrypoint first attempts to contact the mysql-master service and register itself to the replication set. Once that is done, the MySQL master server sends the slave the replicated database.

When scaling down, the MySQL slave is shut down and, because the slave does not have any persistent storage defined, all data on the slave is lost. The MySQL master server then discovers that the slave is not reachable anymore, and it automatically removes it from the replication.

Troubleshooting

This section describes some troubles you might encounter and presents possible resolutions.

Linux Native AIO Failure

Symptom

The MySQL container fails to start and the logs show something like:

151113  5:06:56 InnoDB: Using Linux native AIO
151113  5:06:56  InnoDB: Warning: io_setup() failed with EAGAIN. Will make 5 attempts before giving up.
InnoDB: Warning: io_setup() attempt 1 failed.
InnoDB: Warning: io_setup() attempt 2 failed.
Waiting for MySQL to start ...
InnoDB: Warning: io_setup() attempt 3 failed.
InnoDB: Warning: io_setup() attempt 4 failed.
Waiting for MySQL to start ...
InnoDB: Warning: io_setup() attempt 5 failed.
151113  5:06:59  InnoDB: Error: io_setup() failed with EAGAIN after 5 attempts.
InnoDB: You can disable Linux Native AIO by setting innodb_use_native_aio = 0 in my.cnf
151113  5:06:59 InnoDB: Fatal error: cannot initialize AIO sub-system
151113  5:06:59 [ERROR] Plugin 'InnoDB' init function returned error.
151113  5:06:59 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
151113  5:06:59 [ERROR] Unknown/unsupported storage engine: InnoDB
151113  5:06:59 [ERROR] Aborting

Explanation

MySQL’s storage engine was unable to use the kernel’s AIO (Asynchronous I/O) facilities due to resource limits.

Resolution

Turn off AIO usage entirely, by setting environment variable MYSQL_AIO to have value 0. On subsequent deployments, this arranges for the MySQL configuration variable innodb_use_native_aio to have value 0.

Increase the aio-max-nr kernel resource. The following example examines the current value of aio-max-nr and doubles it.

$ sysctl fs.aio-max-nr
fs.aio-max-nr = 1048576
# sysctl -w fs.aio-max-nr=2097152

This is a per-node resolution and lasts until the next node reboot.

PostgreSQL

Overview

OpenShift Container Platform provides a container image for running PostgreSQL. This image can provide database services based on username, password, and database name settings provided via configuration.

Versions

Currently, OpenShift Container Platform supports versions 9.2, 9.4, and 9.5 of PostgreSQL.

Images

These images come in two flavors, depending on your needs:

RHEL 7

CentOS 7

RHEL 7 Based Image

The RHEL 7 images are available through Red Hat’s subscription registry via:

$ docker pull registry.access.redhat.com/openshift3/postgresql-92-rhel7
$ docker pull registry.access.redhat.com/rhscl/postgresql-94-rhel7
$ docker pull registry.access.redhat.com/rhscl/postgresql-95-rhel7

CentOS 7 Based Image

These images are available on DockerHub. To download them:

$ docker pull openshift/postgresql-92-centos7
$ docker pull centos/postgresql-94-centos7
$ docker pull centos/postgresql-95-centos7

or

$ docker pull centos/postgresql-94-centos7

To use these images, you can either access them directly from these registries or push them into your OpenShift Container Platform Docker registry. Additionally, you can create an ImageStream that points to the image, either in your Docker registry or at the external location. Your OpenShift Container Platform resources can then reference the ImageStream. You can find example ImageStream definitions for all the provided OpenShift Container Platform images.

Configuration and Usage

Initializing the Database

The first time you use the shared volume, the database is created along with the database administrator user and the PostgreSQL postgres user (if you specify the POSTGRESQL_ADMIN_PASSWORD environment variable). Afterwards, the PostgreSQL daemon starts up. If you are re-attaching the volume to another container, then the database, the database user, and the administrator user are not created, and the PostgreSQL daemon starts.

The following command creates a new database pod with PostgreSQL running in a container:

$ oc new-app -e \
    POSTGRESQL_USER=<username>,POSTGRESQL_PASSWORD=<password>,POSTGRESQL_DATABASE=<database_name> \
    registry.access.redhat.com/rhscl/postgresql-94-rhel7

Running PostgreSQL Commands in Containers

OpenShift Container Platform uses Software Collections (SCLs) to install and launch PostgreSQL. If you want to execute a PostgreSQL command inside of a running container (for debugging), you must invoke it using bash.

To do so, first identify the name of the running PostgreSQL pod. For example, you can view the list of pods in your current project:

$ oc get pods

Then, open a remote shell session to the desired pod:

$ oc rsh <pod>

When you enter the container, the required SCL is automatically enabled.

You can now run the psql command from the bash shell to start a PostgreSQL interactive session and perform normal PostgreSQL operations. For example, to authenticate as the database user:

bash-4.2$ PGPASSWORD=$POSTGRESQL_PASSWORD psql -h postgresql $POSTGRESQL_DATABASE $POSTGRESQL_USER
psql (9.2.8)
Type "help" for help.

default=>

When you are finished, enter \q to leave the PostgreSQL session.

Environment Variables

The PostgreSQL user name, password, and database name must be configured with the following environment variables:

Table 3.3. PostgreSQL Environment Variables

Variable Name
Description

POSTGRESQL_USER

User name for the PostgreSQL account to be created. This user has full rights to the database.

POSTGRESQL_PASSWORD

Password for the user account.

POSTGRESQL_DATABASE

Database name.

POSTGRESQL_ADMIN_PASSWORD

Optional password for the postgres administrator user. If this is not set, then remote login to the postgres account is not possible. Local connections from within the container are always permitted without a password.

Warning

You must specify the user name, password, and database name. If you do not specify all three, the pod will fail to start and OpenShift Container Platform will continuously try to restart it.

PostgreSQL settings can be configured with the following environment variables:

Table 3.4. Additional PostgreSQL settings

Variable Name
Description
Default

POSTGRESQL_MAX_CONNECTIONS

Maximum number of client connections allowed.

100

POSTGRESQL_MAX_PREPARED_TRANSACTIONS

Maximum number of transactions that can be in the "prepared" state. If using prepared transactions, the value should be at least as large as POSTGRESQL_MAX_CONNECTIONS.

0

POSTGRESQL_SHARED_BUFFERS

Amount of memory dedicated to PostgreSQL for caching data.

32M

POSTGRESQL_EFFECTIVE_CACHE_SIZE

Estimated amount of memory available for disk caching by the operating system and within PostgreSQL itself.

128M

Volume Mount Points

The PostgreSQL image can be run with mounted volumes to enable persistent storage for the database:

/var/lib/pgsql/data - This is the database cluster directory where PostgreSQL stores database files.

Changing Passwords

Passwords are part of the image configuration, therefore the only supported method to change passwords for the database user (POSTGRESQL_USER) and postgres administrator user is by changing the environment variables POSTGRESQL_PASSWORD and POSTGRESQL_ADMIN_PASSWORD, respectively.

You can view the current passwords by viewing the pod or deployment configuration in the web console or by listing the environment variables with the CLI:

$ oc set env pod <pod_name> --list

Changing database passwords through SQL statements or any way other than through the environment variables aforementioned will cause a mismatch between the values stored in the variables and the actual passwords. Whenever a database container starts, it resets the passwords to the values stored in the environment variables.

To change these passwords, update one or both of the desired environment variables for the related deployment configuration(s) using the oc set env command. If multiple deployment configurations utilize these environment variables, for example in the case of an application created from a template, you must update the variables on each deployment configuration so that the passwords are in sync everywhere. This can be done all in the same command:

$ oc set env dc <dc_name> [<dc_name_2> ...] \
  POSTGRESQL_PASSWORD=<new_password> \
  POSTGRESQL_ADMIN_PASSWORD=<new_admin_password>

Important

Depending on your application, there may be other environment variables for passwords in other parts of the application that should also be updated to match. For example, there could be a more generic DATABASE_USER variable in a front-end pod that should match the database user’s password. Ensure that passwords are in sync for all required environment variables per your application, otherwise your pods may fail to redeploy when triggered.

Updating the environment variables triggers the redeployment of the database server if you have a configuration change trigger. Otherwise, you must manually start a new deployment in order to apply the password changes.

To verify that new passwords are in effect, first open a remote shell session to the running PostgreSQL pod:

$ oc rsh <pod>

From the bash shell, verify the database user’s new password:

bash-4.2$ PGPASSWORD=<new_password> psql -h postgresql $POSTGRESQL_DATABASE $POSTGRESQL_USER -c "SELECT * FROM (SELECT current_database()) cdb CROSS JOIN (SELECT current_user) cu"

If the password was changed correctly, you should see a table like this:

 current_database | current_user
------------------+--------------
 default          | django
(1 row)

From the bash shell, verify the postgres administrator user’s new password:

bash-4.2$ PGPASSWORD=<new_admin_password> psql -h postgresql $POSTGRESQL_DATABASE postgres -c "SELECT * FROM (SELECT current_database()) cdb CROSS JOIN (SELECT current_user) cu"

If the password was changed correctly, you should see a table like this:

 current_database | current_user
------------------+--------------
 default          | postgres
(1 row)

Creating a Database Service from a Template

OpenShift Container Platform provides a template to make creating a new database service easy. The template provides parameter fields to define all the mandatory environment variables (user, password, database name, etc) with predefined defaults including auto-generation of password values. It will also define both a deployment configuration and a service.

The PostgreSQL templates should have been registered in the default openshift project by your cluster administrator during the initial cluster setup. See Loading the Default Image Streams and Templates for more details, if required.

There are two templates available:

PostgreSQL-ephemeral is for development or testing purposes only because it uses ephemeral storage for the database content. This means that if the database pod is restarted for any reason, such as the pod being moved to another node or the deployment configuration being updated and triggering a redeploy, all data will be lost.

PostgreSQL-persistent uses a persistent volume store for the database data which means the data will survive a pod restart. Using persistent volumes requires a persistent volume pool be defined in the OpenShift Container Platform deployment. Cluster administrator instructions for setting up the pool are located here.

You can find instructions for instantiating templates by following these instructions.

Once you have instantiated the service, you can copy the user name, password, and database name environment variables into a deployment configuration for another component that intends to access the database. That component can then access the database via the service that was defined.

MongoDB

Overview

OpenShift Container Platform provides a container image for running MongoDB. This image can provide database services based on username, password, and database name settings provided via configuration.

Versions

Currently, OpenShift Container Platform provides versions 2.4, 2.6, and 3.2 of MongoDB.

Images

These images come in two flavors, depending on your needs:

RHEL 7

CentOS 7

RHEL 7 Based Image

The RHEL 7 images are available through Red Hat’s subscription registry via:

$ docker pull registry.access.redhat.com/openshift3/mongodb-24-rhel7
$ docker pull registry.access.redhat.com/rhscl/mongodb-26-rhel7
$ docker pull registry.access.redhat.com/rhscl/mongodb-32-rhel7

CentOS 7 Based Image

These images are available on DockerHub. To download them:

$ docker pull openshift/mongodb-24-centos7
$ docker pull centos/mongodb-26-centos7
$ docker pull centos/mongodb-32-centos7

To use these images, you can either access them directly from these registries or push them into your OpenShift Container Platform Docker registry. Additionally, you can create an ImageStream that points to the image, either in your Docker registry or at the external location. Your OpenShift Container Platform resources can then reference the ImageStream. You can find example ImageStream definitions for all the provided OpenShift Container Platform images.

Configuration and Usage

Initializing the Database

The first time you use the shared volume, the database is created along with the database administrator user. Afterwards, the MongoDB daemon starts up. If you are re-attaching the volume to another container, then the database, database user, and the administrator user are not created, and the MongoDB daemon starts.

The following command creates a new database pod with MongoDB running in a container:

$ oc new-app -e \
    MONGODB_USER=<username>,MONGODB_PASSWORD=<password>,MONGODB_DATABASE=<database_name>,MONGODB_ADMIN_PASSWORD=<admin_password> \
    registry.access.redhat.com/rhscl/mongodb-26-rhel7

Running MongoDB Commands in Containers

OpenShift Container Platform uses Software Collections (SCLs) to install and launch MongoDB. If you want to execute a MongoDB command inside of a running container (for debugging), you must invoke it using bash.

To do so, first identify the name of the running MongoDB pod. For example, you can view the list of pods in your current project:

$ oc get pods

Then, open a remote shell session to the desired pod:

$ oc rsh <pod>

When you enter the container, the required SCL is automatically enabled.

You can now run mongo commands from the bash shell to start a MongoDB interactive session and perform normal MongoDB operations. For example, to switch to the sampledb database and authenticate as the database user:

bash-4.2$ mongo -u $MONGODB_USER -p $MONGODB_PASSWORD $MONGODB_DATABASE
MongoDB shell version: 2.4.9
connecting to: sampledb
>

When you are finished, press CTRL+D to leave the MongoDB session.

Environment Variables

The MongoDB user name, password, database name, and admin password must be configured with the following environment variables:

Table 3.5. MongoDB Environment Variables

Variable Name
Description

MONGODB_USER

User name for MongoDB account to be created.

MONGODB_PASSWORD

Password for the user account.

MONGODB_DATABASE

Database name.

MONGODB_ADMIN_PASSWORD

Password for the admin user.

Warning

You must specify the user name, password, database name, and admin password. If you do not specify all four, the pod will fail to start and OpenShift Container Platform will continuously try to restart it.

Note

The administrator user name is set to admin and you must specify its password by setting the MONGODB_ADMIN_PASSWORD environment variable. This process is done upon database initialization.

MongoDB settings can be configured with the following environment variables:

Table 3.6. Additional MongoDB Settings

Variable Name
Description
Default

MONGODB_NOPREALLOC

Disable data file preallocation.

true

MONGODB_SMALLFILES

Set MongoDB to use a smaller default data file size.

true

MONGODB_QUIET

Runs MongoDB in a quiet mode that attempts to limit the amount of output.

true

MONGODB_TEXT_SEARCH_ENABLED

(MongoDB version 2.4 only) Enables the text search feature.

Note

Text search is enabled by default in MongoDB versions 2.6 and higher, and therefore has no configurable parameter.

false

Volume Mount Points

The MongoDB image can be run with mounted volumes to enable persistent storage for the database:

/var/lib/mongodb - This is the database directory where MongoDB stores database files.

Changing Passwords

Passwords are part of the image configuration, therefore the only supported method to change passwords for the database user (MONGODB_USER) and admin user is by changing the environment variables MONGODB_PASSWORD and MONGODB_ADMIN_PASSWORD, respectively.

You can view the current passwords by viewing the pod or deployment configuration in the web console or by listing the environment variables with the CLI:

$ oc set env pod <pod_name> --list

Changing database passwords directly in MongoDB causes a mismatch between the values stored in the variables and the actual passwords. Whenever a database container starts, it resets the passwords to the values stored in the environment variables.

To change these passwords, update one or both of the desired environment variables for the related deployment configuration(s) using the oc set env command. If multiple deployment configurations utilize these environment variables, for example in the case of an application created from a template, you must update the variables on each deployment configuration so that the passwords are in sync everywhere. This can be done all in the same command:

$ oc set env dc <dc_name> [<dc_name_2> ...] \
  MONGODB_PASSWORD=<new_password> \
  MONGODB_ADMIN_PASSWORD=<new_admin_password>

Important

Depending on your application, there may be other environment variables for passwords in other parts of the application that should also be updated to match. For example, there could be a more generic DATABASE_USER variable in a front-end pod that should match the database user’s password. Ensure that passwords are in sync for all required environment variables per your application, otherwise your pods may fail to redeploy when triggered.

Updating the environment variables triggers the redeployment of the database server if you have a configuration change trigger. Otherwise, you must manually start a new deployment in order to apply the password changes.

To verify that new passwords are in effect, first open a remote shell session to the running MongoDB pod:

$ oc rsh <pod>

From the bash shell, verify the database user’s new password:

bash-4.2$ mongo -u $MONGODB_USER -p <new_password> $MONGODB_DATABASE --eval "db.version()"

If the password was changed correctly, you should see output like this:

MongoDB shell version: 2.6.9
connecting to: sampledb
2.6.9

To verify the admin user’s new password:

bash-4.2$ mongo -u admin -p <new_admin_password> admin --eval "db.version()"

If the password was changed correctly, you should see output like this:

MongoDB shell version: 2.4.9
connecting to: admin
2.4.9

Creating a Database Service from a Template

OpenShift Container Platform provides a template to make creating a new database service easy. The template provides parameter fields to define all the mandatory environment variables (user, password, database name, etc) with predefined defaults including auto-generation of password values. It will also define both a deployment configuration and a service.

The MongoDB templates should have been registered in the default openshift project by your cluster administrator during the initial cluster setup. See Loading the Default Image Streams and Templates for more details, if required.

There are two templates available:

mongodb-ephemeral is for development/testing purposes only because it uses ephemeral storage for the database content. This means that if the database pod is restarted for any reason, such as the pod being moved to another node or the deployment configuration being updated and triggering a redeploy, all data will be lost.

mongodb-persistent uses a persistent volume store for the database data which means the data will survive a pod restart. Using persistent volumes requires a persistent volume pool be defined in the OpenShift Container Platform deployment. Cluster administrator instructions for setting up the pool are located here.

You can find instructions for instantiating templates by following these instructions.

Once you have instantiated the service, you can copy the user name, password, and database name environment variables into a deployment configuration for another component that intends to access the database. That component can then access the database via the service that was defined.

Using MongoDB Replication

Note

Enabling clustering for database images is currently in Technology Preview and not intended for production use.

Red Hat provides a proof-of-concept template for MongoDB replication (clustering); you can obtain the example template from GitHub.

For example, to upload the example template into the current project’s template library:

$ oc create -f \
    https://raw.githubusercontent.com/openshift/mongodb/master/2.4/examples/replica/mongodb-clustered.json

Important

The example template does not use persistent storage. When you lose all members of the replication set, your data will be lost.

The following sections detail the objects defined in the example template and describe how they work together to start a cluster of MongoDB servers implementing master-slave replication and automated failover. This is the recommended replication strategy for MongoDB.

Creating the Deployment Configuration

To set up MongoDB replication, a deployment configuration is defined in the example template that defines a replication controller. The replication controller manages the members of the MongoDB cluster.

To tell a MongoDB server that the member will be part of the cluster, additional environment variables are provided for the container defined in the replication controller pod template:

Variable Name
Description
Default

MONGODB_REPLICA_NAME

Specifies the name of the replication set.

rs0

MONGODB_KEYFILE_VALUE

See: Generate a Key File

generated

Example 3.4. Deployment Configuration Object Definition in the Example Template

kind: DeploymentConfig
apiVersion: v1
metadata:
  name: "${MONGODB_SERVICE_NAME}"
spec:
  strategy:
    type: Recreate
    resources: {}
  triggers:
    - type: ConfigChange
  replicas: 3
  selector:
    name: mongodb-replica
  template:
    metadata:
      labels:
        name: mongodb-replica
    spec:
      containers:
        - name: member
          image: openshift/mongodb-24-centos7
          env:
            - name: MONGODB_USER
              value: "${MONGODB_USER}"
            - name: MONGODB_PASSWORD
              value: "${MONGODB_PASSWORD}"
            - name: MONGODB_DATABASE
              value: "${MONGODB_DATABASE}"
            - name: MONGODB_ADMIN_PASSWORD
              value: "${MONGODB_ADMIN_PASSWORD}"
            - name: MONGODB_REPLICA_NAME
              value: "${MONGODB_REPLICA_NAME}"
            - name: MONGODB_SERVICE_NAME
              value: "${MONGODB_SERVICE_NAME}"
            - name: MONGODB_KEYFILE_VALUE
              value: "${MONGODB_KEYFILE_VALUE}"
          ports:
            - containerPort: 27017
              protocol: TCP
  restartPolicy: Never
  dnsPolicy: ClusterFirst

After the deployment configuration is created and the pods with MongoDB cluster members are started, they will not be initialized. Instead, they start as part of the rs0 replication set, as the value of MONGODB_REPLICA_NAME is set to rs0 by default.

Creating the Service Pod

To initialize members created by the deployment configuration, the pods are started with the initiate argument, which instructs the startup script to behave slightly differently than a regular, stand-alone MongoDB database.

Example 3.5. Deployment Configuration Object Definition in the Example Template

- kind: DeploymentConfig
  apiVersion: v1
  metadata:
    name: "${MONGODB_SERVICE_NAME}"
  spec:
    strategy:
      type: Recreate
      recreateParams:
        post:
          failurePolicy: Retry
          execNewPod:
            command: ["run-mongod","initiate"]
            containerName: mongodb
            env:
            - name: MONGODB_INITIAL_REPLICA_COUNT
              value: '3'
    triggers:
    - type: ConfigChange
    replicas: 3
    selector:
      name: mongodb-replica
    template:
      metadata:
        labels:
          name: mongodb-replica
      spec:
        containers:
        - name: mongodb
          image: openshift/mongodb-24-centos7
          readinessProbe:
            tcpSocket:
              port: 27017
            initialDelaySeconds: 15
            timeoutSeconds: 1
          env:
          - name: MONGODB_USER
            value: "${MONGODB_USER}"
          - name: MONGODB_PASSWORD
            value: "${MONGODB_PASSWORD}"
          - name: MONGODB_DATABASE
            value: "${MONGODB_DATABASE}"
          - name: MONGODB_ADMIN_PASSWORD
            value: "${MONGODB_ADMIN_PASSWORD}"
          - name: MONGODB_REPLICA_NAME
            value: "${MONGODB_REPLICA_NAME}"
          - name: MONGODB_SERVICE_NAME
            value: "${MONGODB_SERVICE_NAME}"
          - name: MONGODB_KEYFILE_VALUE
            value: "${MONGODB_KEYFILE_VALUE}"
          ports:
          - containerPort: 27017

Creating a Headless Service

The initiate argument in the container specification above instructs the container to first discover all running member pods within the MongoDB cluster. To achieve this, a headless service is defined named mongodb in the example template.

To have a headless service, the portalIP parameter in the service definition is set to None. Then you can use a DNS query to get a list of the pod IP addresses that represents the current endpoints for this service.

Example 3.6. Headless Service Object Definition in the Example Template

kind: "Service"
apiVersion: "v1"
metadata:
  name: "${MONGODB_SERVICE_NAME}"
  labels:
    name: "${MONGODB_SERVICE_NAME}"
spec:
  ports:
    - protocol: "TCP"
      port: 27017
      targetPort: 27017
      nodePort: 0
  selector:
    name: "mongodb-replica"
  portalIP: "None"
  type: "ClusterIP"
  sessionAffinity: "None"
status:
  loadBalancer: {}

Creating the Final Replication Set

When the script that runs as the container entrypoint has the IP addresses of all running MongoDB members, it creates a MongoDB replication set configuration where it lists all member IP addresses. It then initiates the replication set using rs.initiate(config). The script waits until MongoDB elects the PRIMARY member of the cluster.

Once the PRIMARY member has been elected, the entrypoint script starts creating MongoDB users and databases.

Clients can then start using the MongoDB instance by sending the queries to the mongodb service. As this service is a headless service, they do not need to provide the IP address. Clients can use mongodb:27017 for connections. The service then sends the query to one of the members in the replication set.

Scaling the MongoDB Replication Set

To increase the number of members in the cluster:

$ oc scale rc mongodb-1 --replicas=<number>

This tells the replication controller to create a new MongoDB member pod. When a new member is created, the member entrypoint first attempts to discover other running members in the cluster. It then chooses one and adds itself to the list of members. Once the replication configuration is updated, the other members replicate the data to a new pod and start a new election.

Chapter 4. Docker Images

Overview

You can use arbitrary conatiner images in your OpenShift Container Platform instance, for example those found on the Docker Hub. For instructions on how to enable images to run with USER in the Dockerfile, see Managing Security Context Constraints.

Chapter 5. Other Images

Overview

This topic group includes information on other container images available for OpenShift Container Platform users.

Jenkins

Overview

OpenShift Container Platform provides a container image for running Jenkins. This image provides a Jenkins server instance which can be used to set up a basic flow for continuous testing, integration, and delivery.

This image also includes a sample Jenkins job which triggers a new build of a BuildConfig defined in OpenShift Container Platform, tests the output of that build, and then on successful build, retags the output to indicate the build is ready for production.

Versions

OpenShift Container Platform follows the LTS releases of Jenkins.

Images

This image comes in two flavors, depending on your needs:

RHEL 7

CentOS 7

RHEL 7 Based Image

The RHEL 7 image is available through Red Hat’s subscription registry:

$ docker pull registry.access.redhat.com/openshift3/jenkins-1-rhel7

CentOS 7 Based Image

This image is available on DockerHub. To download it:

$ docker pull openshift/jenkins-1-centos7

To use these images, you can either access them directly from these registries or push them into your OpenShift Container Platform Docker registry. Additionally, you can create an ImageStream that points to the image, either in your Docker registry or at the external location. Your OpenShift Container Platform resources can then reference the ImageStream. You can find example ImageStream definitions for all the provided OpenShift Container Platform images.

Configuration and Usage

Initializing Jenkins

The first time you start Jenkins, the configuration is created along with the administrator user and password. The default login is admin/password. The default password can be configured by setting the JENKINS_PASSWORD environment variable.

<<<<<<< HEAD The following command creates a new Jenkins pod with Jenkins running in a container:

OpenShift Container Platform OAuth authentication provided by the OpenShift Login plug-in.

Standard authentication provided by Jenkins

==== OpenShift Container Platform OAuth authentication

OAuth authentication is activated by configuring the Configure Global Security panel in the Jenkins UI, or by setting the OPENSHIFT_ENABLE_OAUTH environment variable on the Jenkins Deployment Config to anything other than false. This activates the OpenShift Login plug-in, which retrieves the configuration information from pod data or by interacting with the OpenShift Container Platform API server.

Valid credentials are controlled by your identity provider. For example, if Allow All is the default identity provider, you can provide any non-empty string for both the user name and password.

For non-browser access, the OpenShift Login plug-in also supports using the HTTP bearer token authorization header to supply valid credentials for accessing Jenkins. Ensure to use the token associated with the serviceaccount for the project in which Jenkins is running, which, if you started Jenkins using the jenkins-ephemeral or jenkins-persistent templates, are found by using:

$ oc describe serviceaccount jenkins
$ oc describe secret <serviceaccount secret name>

Valid users are automatically added to the Jenkins authorization matrix at log in, where OpenShift Container Platform Roles dictate the specific Jenkins permissions the user will have.

Users with the admin role will have the traditional Jenkins administrative user permissions. Users with the edit or view role will have progressively less permissions. See the Jenkins image source repository README for the specifics on the OpenShift roles to Jenkins permissions mappings.

Note

The admin user that is pre-populated in the OpenShift Container Platform Jenkins image with administrative privileges will not be given those privileges when OpenShift Container Platform OAuth is used, unless the OpenShift Container Platform cluster administrator explicitly defines that user in the OpenShift Container Platform identity provider and assigns the admin role to the user.

Jenkins' users permissions can be changed after the users are initially established. The OpenShift Login plug-in polls the OpenShift Container Platform API server for permissions and updates the permissions stored in Jenkins for each user with the permissions retrieved from OpenShift Container Platform. If the Jenkins UI is used to update permissions for a Jenkins user, the permission changes are overwritten the next time the plug-in polls OpenShift Container Platform.

You can control how often the polling occurs with the OPENSHIFT_PERMISSIONS_POLL_INTERVAL environment variable. The default polling interval is five minutes.

Ensure the the default image streams and templates are already installed.

Create a new Jenkins application using:

Persistent volumes:

$ oc new-app jenkins-persistent

Or an EmptyDir type volume (where configuration does not persist across pod restarts):

$ oc new-app jenkins-ephemeral

Note

If you instantiate the template against releases prior to v3.4 of OpenShift Container Platform, standard Jenkins authentication is used, and the default 'admin' account will exist with password 'password'. See Jenkins Standard Authentication for details about changing this password.

==== Jenkins Standard Authentication

Jenkins authentication is used by default if the image is run outside of OpenShift Container Platform.

The first time Jenkins starts, the configuration is created along with the administrator user and password. The default user credentials are admin and password. Configure the default password by setting the JENKINS_PASSWORD environment variable when using (and only when using) standard Jenkins authentication.

To create a new Jenkins application using standard Jenkins authentication: >>>>>>> 7cdc862…​ More anchor fixes

$ oc new-app -e \
    JENKINS_PASSWORD=<password> \
    openshift/jenkins-1-centos7

=== Environment Variables

The Jenkins password can be configured with the following environment variable:

Table 5.1. Jenkins Environment Variables

Variable name
Description

JENKINS_PASSWORD

Password for the admin user.

=== Volume Mount Points The Jenkins image can be run with mounted volumes to enable persistent storage for the configuration:

/var/lib/jenkins - This is the data directory where Jenkins stores configuration files including job definitions.

== Creating a Jenkins Service from a Template

Templates provide parameter fields to define all the environment variables (password) with predefined defaults. OpenShift Container Platform provides templates to make creating a new Jenkins service easy. The Jenkins templates should have been registered in the default openshift project by your cluster administrator during the initial cluster setup. See Loading the Default Image Streams and Templates for more details, if required.

The two available templates both define a deployment configuration and a service, but differ in their storage strategy, which affects whether or not the Jenkins content persists across a pod restart.

Note

A pod may be restarted when it is moved to another node, or when an update of the deployment configuration triggers a redeployment.

jenkins-ephemeral uses ephemeral storage. On pod restart, all data is lost. This template is useful for development or testing only.

jenkins-persistent uses a persistent volume store. Data survives a pod restart. To use a persistent volume store, the cluster administrator must define a persistent volume pool in the OpenShift Container Platform deployment.

Once selected, you must instantiate the template to be able to use Jenkins.

== Using Jenkins as a Source-To-Image builder

To customize the official OpenShift Container Platform Jenkins image, you have two options:

Use Docker layering.

Use the image as a Source-To-Image builder, described here.

You can use S2I to copy your custom Jenkins Jobs definitions, additional plug-ins or replace the provided config.xml file with your own, custom, configuration.

In order to include your modifications in the Jenkins image, you need to have a Git repository with the following directory structure:

plugins

This directory contains those binary Jenkins plug-ins you want to copy into Jenkins.

plugins.txt

This file lists the plug-ins you want to install:

pluginId:pluginVersion

configuration/jobs

This directory contains the Jenkins job definitions.

configuration/config.xml

This file contains your custom Jenkins configuration.

The contents of the configuration/ directory will be copied into the /var/lib/jenkins/ directory, so you can also include additional files, such as credentials.xml, there.

The following is an example build configuration that customizes the Jenkins image in OpenShift Container Platform:

apiVersion: v1
kind: BuildConfig
metadata:
  name: custom-jenkins-build
spec:
  source:
    git:
      uri: https://github.com/custom/repository
    type: Git
  strategy:
    sourceStrategy:
      from:
        kind: ImageStreamTag
        name: jenkins:latest
        namespace: openshift
    type: Source
  output:
    to:
      kind: ImageStreamTag
      name: custom-jenkins:latest

The source field defines the source Git repository with the layout described above.

The strategy field defines the original Jenkins image to use as a source image for the build.

The output field defines the resulting, customized Jenkins image you can use in deployment configuration instead of the official Jenkins image.

== Using the Jenkins Kubernetes Plug-in to Run Jobs

The official OpenShift Container Platform Jenkins image includes the pre-installed Kubernetes plug-in that allows Jenkins slaves to be dynamically provisioned on multiple container hosts using Kubernetes and OpenShift Container Platform.

To facilitate the using of the Kubernetes plug-in, OpenShift Container Platform provides three images suitable for use as Jenkins slaves..

<<<<<<< HEAD The first is a base image for Jenkins slaves. It pulls in both required tools (headless Java, the Jenkins JNLP client) and generally useful ones (including git, tar, zip, nss among others) as well as establishing the JNLP slave agent as the entrypoint. The image also includes the oc client tooling for invoking command line operations from within Jenkins jobs. And it provides Dockerfiles for both Centos and RHEL images.

It pulls in both the required tools (headless Java, the Jenkins JNLP client) and the useful ones (including git, tar, zip, nss among others).

It establishes the JNLP slave agent as the entrypoint.

It includes the oc client tooling for invoking command line operations from within Jenkins jobs, and

It provides Dockerfiles for both Centos and RHEL images. >>>>>>> 7cdc862…​ More anchor fixes

Two images which extend this base image are also provided:

Maven

NodeJS

Both the Maven and NodeJS slave images are configured as Kubernetes Pod Tempate images within the OpenShift Container Platform Jenkins image’s configuration for the Kubernetes plugin. That configuration includes labels for each which can be applied to any of your Jenkins jobs under their "Restrict where this project can be run" setting. If the label is applied, execution of the given job will be done under an OpenShift Container Platform Pod running the respective slave image.

The Maven and NodeJS Jenkins slave images provide Dockerfiles for both Centos and RHEL that you can reference when building new slave images. Also note the contrib and contrib/bin subdirectories. They allow for the insertion of configuration files and executable scripts for your image.

The Jenkins image also provides auto-discovery and auto-configuration <<<<<<< HEAD of slave images for the Kubernetes plug-ins by scanning the project Jenkins is deployed in for existing image streams with the label role set to jenkins-slave.

When an image stream with this label is found, corresponding Kubernetes plug-in configuration is generated so you can assign your Jenkins

of slave images for the Kubernetes plug-in. The Jenkins image searches for these in the existing image streams within the project that it is running in. The search specifically looks for image streams that have the label role set to jenkins-slave.

When it finds an image stream with this label, it generates the corresponding Kubernetes plug-in configuration so you can assign your Jenkins >>>>>>> 7cdc862…​ More anchor fixes jobs to run in a pod running the container image provided by the image stream.

Note: this scanning is only performed once, when the Jenkins master is starting. If you label additional imagestreams, the Jenkins master will need to be restarted to pick up the additional images.

To use a container image as an Jenkins slave, the image must run the slave agent as an entrypoint. For more details about this, refer to the official Jenkins documentation.

== Tutorial

For more details on the sample job included in this image, see this tutorial.

== xPaaS Middleware Images :leveloffset: +2

= Overview :experimental:

Red Hat offers a containerized xPaaS image for a host of middleware products that are designed for use with OpenShift Container Platform. With the 3.2 release of OpenShift Container Platform, the documentation for these images has been migrated to the Red Hat Customer Portal.

= Revision History: Using Images :experimental:

== Tue Dec 20 2016

Affected Topic
Description of Change

Source-to-Image (S2I) → PHP

Added the DOCUMENTROOT environment variable to the PHP Environment Variables table.

== Thu Oct 27 2016

OpenShift Container Platform 3.3.1 release.

Affected Topic
Description of Change

Source-to-Image (S2I) → .NET Core

New topic about using .NET Core with OpenShift Container Platform.

== Tue Sep 27 2016

OpenShift Container Platform 3.3 initial release.

Affected Topic
Description of Change

Source-to-Image (S2I) → Python

Added the PIP_INDEX_URL environment variable to the Configuration section.

Database Images → MySQL

Updated the Additional MySQL Settings table in the Environment Variables section with new variables.