Getting Started Guide

Red Hat Container Development Kit 2.0

Getting Started Guide

Robert Krátký

Red Hat Developer Group Documentation Team

Abstract

A quick-start guide to Red Hat Container Development Kit.

Preface

Important

Please, note that the Red Hat Container Development Kit 2.0 product has been released as Technical Preview. This impacts the level of support offered by Red Hat. For additional information, please, see Technology Preview Features Support Scope.

Chapter 1. Introduction to Red Hat Container Development Kit

Red Hat Container Development Kit (CDK) is a set of tools that enables developers to quickly and easily set up an environment for developing and testing containerized applications on the Red Hat Enterprise Linux platform. CDK is available for Microsoft Windows, Mac OS X, and Linux operating systems, thus allowing developers to use their favorite platform while producing applications ready to be deployed in the Red Hat Enterprise Linux ecosystem.

CDK is a part of the Red Hat Developers program, which provides tools, resources, and support for developers who wish to utilize Red Hat solutions and products to create applications, both locally and in the cloud. For additional information and to register to become a part of the program, visit developers.redhat.com.

This Getting Started Guide describes the individual components that together form CDK, followed by instructions on how to obtain, install, and configure the components, so that you can start using the resulting environment to interact with containers and develop containerized applications.

See the Red Hat Container Development Kit 2.0 Release Notes and Known Issues to learn about the main features of the product and about problems that you may encounter when using this version.

Detailed installation instructions for setting up CDK on each of the supported platforms (Microsoft Windows, Mac OS X, and Linux) are available in the CDK Installation Guide. Practical usage examples, including advanced topics, such as the development of multi-container applications and container orchestration using Kubernetes or OpenShift, will be available in the Container Development Guide (to be published).

1.1. About Containers

Containers are a form of operating-system-level virtualization, which is based on sharing the underlying host system’s kernel while providing multiple user-space instances (software containers). Containers are easier to build and initialize than hardware-level virtual machines, which makes them useful for situations where virtual environments need to be deployed rapidly or in large numbers. Applications running inside virtual software containers remain isolated from the host system.

1.2. About CDK

CDK enables the development of containers on Red Hat Enterprise Linux, regardless of what operating system you use on your development workstation. The core of the development environment is a virtualized instance of Red Hat Enterprise Linux managed by Vagrant, an open-source tool for using light-weight, portable, and consistent development environments. Vagrant is utilized to bring up a pre-built Red Hat Enterprise Linux virtual machine with the CDK software components installed. Virtual machines that are packaged for use with Vagrant are called boxes.

Once you have the CDK software components installed, you can explore Linux container development using Docker, an open-source project that automates the deployment of applications inside of software containers. Docker is built upon a number of key Linux technologies that provide the capabilities to keep containers isolated and secure while controlling resource usage. For actual deployment and orchestration of containerized applications, CDK offers OpenShift with Kubernetes, a platform as a service (PaaS) product, which can be used to maintain underlying services and scale running applications as needed.

After the installation of CDK, the technology stack that is available to you for container development is:

Layer DescriptionTechnology

Your Containers

Your application running in containers

Container management

Docker service

Development VM

Red Hat Enterprise Linux Server 7

VM management

Vagrant

Virtualization provider

Virtualbox or libvirt/KVM

Host machine OS

Microsoft Windows, Mac OS X, or Red Hat Enterprise Linux 7

1.3. About Vagrant

Vagrant has become a de facto standard for packaging and distributing development environments that run using most of the popular virtualization platforms on Windows, Mac OS X, and Linux as well as in the cloud with plugins for OpenStack, Amazon Web Services (AWS), and other environments.

Vagrant uses a single configuration file, the Vagrantfile, to describe a development environment. Using a Vagrantfile and a virtual-machine image packaged as a Vagrant box, a single command, vagrant up, brings up a consistent development environment that includes networking and support for folders that are shared with the host OS for moving code, data, or configuration.

CDK includes a Vagrant box with a Red Hat Enterprise Linux system that is preconfigured to provide an environment for easy container development. The supplied Vagrant box can be deployed using either VirtualBox or KVM (with libvirt) as a virtualization platform. CDK also includes two Vagrantfiles that demonstrate Vagrant provisioning, which includes setting up private networking that exposes services from the virtual machine to the host system and other configuration tasks.

The vagrant ssh command is used to log into Vagrant boxes. The configuration details for networking and SSH keys are handled automatically by Vagrant.

1.3.1. Understanding Vagrant Configuration

Vagrant’s power for creating and distributing portable and reproducible environments derives from using a single file (Vagrantfile) to describe the target environment. A Vagrantfile defines required resources, such as virtual-machine images, networking, and provisioning steps. A separate directory containing a Vagrantfile is used for each target environment.

1.3.1.1. Managing Vagrantfiles

Vagrant commands that take action on a specific environment need to either specify the ID of the environment (if it has already been initialized) or be executed in the directory that contains the environment’s Vagrantfile. That directory forms a 'root' directory for the environment. Within this 'root' directory, Vagrant stores state information for the given environment in the .vagrant subdirectory.

CDK includes a number of sample Vagrantfiles in separate directories with a README file in each one. Start by changing into the directories, viewing the README and Vagrantfile files, and then starting the environment with the vagrant up command.

Note

The tilde character (~) used in a file-system path denotes a user’s home directory on Unix-based operating systems, such as Mac OS X or Linux. Therefore, ~/.vagrant.d on Linux or Mac OS X corresponds to %USERPROFILE%\.vagrant.d on Windows systems.

In addition to the per-environment configuration and state directories, Vagrant uses the ~/.vagrant.d directory to store data that applies to all Vagrant environments run by a given user. When a Vagrant box is added, or plugins are installed, they are added to ~/.vagrant.d. That is, when you run the vagrant box add command, the box’s Vagrantfile is installed in the per-user Vagrant directory, ~/.vagrant.d/boxes/. Since this is stored in the user’s home directory, each user is completely independent and not able to see Vagrant boxes or plugins installed by another user.

Note

Vagrant does not use a concept of system-wide configuration, so even if you run Vagrant as root (Administrator), it only makes changes in the root’s home directory, and these changes are not visible to regular users.

Each Vagrant box that you download or build has its own Vagrantfile, which provides basic configuration for that box. When a Vagrant box is added, the included Vagrantfile is copied into the per-user ~/.vagrant.d directory. The settings in the box’s Vagrantfile can be overridden with the per-environment Vagrantfile.

Finally, there is per-user Vagrantfile in ~/.vagrant.d for configuration that should be available to all of the user’s Vagrant environments. This file is not created by default.

1.3.2. Vagrant Synchronized Folders

When a box is brought up, Vagrant either copies or shares files from the host machine that are in the same directory as the Vagrantfile into the /vagrant directory on the virtual machine. This provides a convenient and automated method to move code, data, and configuration from your host machine to your Vagrant boxes.

A number of methods are available for sharing folders or making copies, such as SSHFS, rsync, NFS, or VirtualBox shared folders. The one that will be used depends on a number of factors, including the host OS, virtualization platform, and installed software. The preferred method used by CDK is SSHFS, which is made available by the vagrant-sshfs plugin.

The type of synchronization used for each shared folder can be set in the definition for the shared folder in the Vagrantfile (the config.vm.synced_folder option). Shared folder definitions may also be in the Vagrantfile that comes with a Vagrant box. This is important to remember if you are trying to completely disable shared folders or change the method used for sharing data.

See the CDK Installation Guide for instructions on how to enable the various folder-synchronization methods on different host systems.

Chapter 2. Installing Red Hat Container Development Kit

Installation steps for setting up CDK on your development workstation (Windows, Mac OS X, Red Hat Enterprise Linux, or Fedora) are described in detail in the CDK Installation Guide. This section only provides a concise outline of the installation procedure for reference purposes.

Regardless of the host operating system you use, the installation of CDK always involves the following steps:

  1. Installing or enabling a virtualization provider (VirtualBox on Microsoft Windows and Mac OS X, libvirt/KVM on Red Hat Enterprise Linux or Fedora).
  2. Installing Vagrant.
  3. Downloading CDK Vagrant box for your virtualization provider.
  4. Downloading and unpacking CDK Tools.
  5. Installing additional auxiliary tools, such as rsync (in case of Microsoft Windows).
  6. Initializing the obtained Vagrant box.

Chapter 3. Interacting with the CDK Vagrant Box

Following the creation and configuration of the CDK Vagrant box using the vagrant up command, you can interact with the running virtual machine using the vagrant command. Using the vagrant-service-manager plugin, you can set up your host workstation to interact with the Docker service running inside the Vagrant box.

3.1. Using the vagrant-service-manager Plugin

On the host machine, you can use the vagrant-service-manager plugin to obtain information about the Docker, OpenShift, and Kubernetes services running in the virtual machine. It displays environment variables that need to be set on the host system (your development workstation) to enable host-based tools (such as the Eclipse IDE, the docker command, or OpenShift’s oc command) to interact with the Docker daemon from the virtual machine.

The vagrant-service-manager plugin automatically recognizes the host operationg system and outputs information based on the platform.

3.1.1. Setting the Host Environment on Linux and Mac OS X

Run the following command from the directory in which the Vagrant box was initialized (in this example, the rhel-ose Vagrantfile was used to provision the CDK Vagrant box):

~/cdk/components/rhel/rhel-ose]$ vagrant service-manager env
Configured services:
docker - running
openshift - running
kubernetes - stopped

docker env:
# Set the following environment variables to enable access to the
# docker daemon running inside of the vagrant virtual machine:
export DOCKER_HOST=tcp://10.1.2.2:2376
export DOCKER_CERT_PATH=/home/john/down/cdk/components/rhel/rhel-ose/.vagrant/machines/default/libvirt/docker
export DOCKER_TLS_VERIFY=1
export DOCKER_API_VERSION=1.21
# run following command to configure your shell:
# eval "$(vagrant service-manager env docker)"

openshift env:
You can access the OpenShift console on: https://10.1.2.2:8443/console
To use OpenShift CLI, run: oc login https://10.1.2.2:8443

Run the following command to set the required environment variables, so that the docker client on the host system can be used to interact with the Docker service running inside the CDK virtual machine:

~]$ eval "$(vagrant service-manager env docker)"

3.1.2. Setting Up the Host Environment on Windows

Run the following command from the directory in which the Vagrant box was initialized (in this example, the rhel-ose Vagrantfile was used to provision the CDK Vagrant box).

~/cdk/components/rhel/rhel-ose]$ vagrant service-manager env docker
# Set the following environment variables to enable access to the
# docker daemon running inside of the vagrant virtual machine:
export DOCKER_HOST=tcp://10.1.2.5:2376
export DOCKER_CERT_PATH='C:\cygwin64\home\cdk\cdk\components\rhel\rhel-ose\.vagrant\machines\default\virtualbox\docker\'
export DOCKER_TLS_VERIFY=1
export DOCKER_API_VERSION=1.21
# run following command to configure your shell:
# eval "$(VAGRANT_NO_COLOR=1 vagrant service-manager env docker | tr -d '\r')"

openshift env:
You can access the OpenShift console on: https://10.1.2.2:8443/console
To use OpenShift CLI, run: oc login https://10.1.2.2:8443

To set the required environment variables, so that the docker.exe client on the host system can be used to interact with the Docker service running inside the CDK virtual machine, you need to run the following commands (note that you need to use the Cygwin Bash environment for the commands to work properly):

~]$ export VAGRANT_DETECTED_OS=cygwin

~]$ eval "$(VAGRANT_NO_COLOR=1 vagrant service-manager env docker | tr -d '\r')"

Chapter 4. Using the Docker Service

When you initialize the CDK virtual machine (using the vagrant up command), various services are automatically pre-configured and running — depending on the Vagrantfile you used to provision the CDK box. The Docker service is running in all cases, and you can use it immediately after the virtual machine is launched. While it is possible to use and interact with the Docker service using GUI tools (for example, the integrated Docker support provided by the Eclipse IDE), this section introduces a number of basic docker commands to get you started using the Docker service from the command line.

Command-line usage of the Docker service provided by the CDK box is possible both from within the virtual machine and from the host machine — see section Using the vagrant-service-manager Plugin for instructions on how to set up your host machine to interact with the Docker service running inside the CDK virtual machine.

See the Get Started with Docker Formatted Container Images chapter of the Red Hat Enterprise Linux Atomic Host 7 Getting Started with Containers guide for a more thorough introduction into the Docker service.

4.1. Preparing Your Host System for Using Docker

To use the docker command on your host system to interact with the Docker service running inside the CDK virtual machine, you need to obtain and install the docker executable.

Important

It is necessary to use a Docker client version that uses the same Docker API version as is provided by the CDK box. In Red Hat CDK 2.0, the version of the Docker API is 1.21, which can only be used with Docker clients versions 1.9.x. See the client-API version-mapping table at Docker Remote API for reference.

Other versions of the Docker client do not work properly with the Docker service provided by the CDK box. If you have a different version of the Docker client installed (for example, through you distribution’s packaging system or as a part of Docker Toolbox on Mac OS X or Windows), make sure you use the client installed by following the instructions in this section to interact with the Docker service in CDK.

If you intend to use Docker (and the docker command) only from within the CDK virtual machine, no preparation is required — the docker command is installed in the CDK box by default.

4.1.1. Installing the docker Executable on Red Hat Enterprise Linux

Install the docker package, which provides the docker executable. The package is available from the rhel-7-server-extras-rpms (Red Hat Enterprise Linux 7 Server - Extras) repository. Use the following command as root to enable the repository:

~]# subscription-manager repos --enable=rhel-7-server-extras-rpms

Install the docker package using the following command as root:

~]# yum install -y docker

4.1.2. Installing the docker Executable on Fedora

If you already have the docker binary installed on your system (for example, from the docker package from an RPM repository), check that it is the correct version (1.9.1) for use with the Docker service provided by the CDK virtual machine by running the following command:

~]$ docker version
Client:
 Version:         1.9.1

[...]

If the version of the docker binary is different from what is required for working with the Docker service provided by the CDK box, see the Docker binary installation procedure.

If you do not have the docker binary installed, check what version is available from the Fedora repository by running the following command:

~]$ dnf info docker
Last metadata expiration check: 1:21:17 ago on Tue Apr 19 12:52:30 2016.
Installed Packages
Name        : docker
Arch        : x86_64
Epoch       : 2
Version     : 1.9.1
Release     : 9.gitee06d03.fc23
Size        : 38 M
Repo        : @System
From repo   : updates
Summary     : Automates deployment of containerized applications
URL         : https://github.com/projectatomic/docker
License     : ASL 2.0
Description : Docker is an open-source engine that automates...

[...]

If the correct version (1.9.x) is available from the repository, install the docker package by running the following command as root:

~]# dnf install -y docker

If you do not have the required version (1.9.x) installed, nor is it available from the distribution’s package repository, follow these steps:

  1. Download the docker-1.9.1 binary from https://get.docker.com/builds/Linux/x86_64/docker-1.9.1 to a directory of your choice. In this example, the ~/docker directory is used:

    ~]$ mkdir ~/docker
    
    ~]$ cd ~/docker
    
    ~/docker]$ wget https://get.docker.com/builds/Linux/x86_64/docker-1.9.1
  2. Add the ~/docker directory to the PATH environmental variable, so that the docker-1.9.1 command can be used without specifying its location:

    ~/docker]$ export PATH=$PATH:~/docker
  3. Make the binary executable:

    ~/docker]$ chmod 764 docker-1.9.1
Note

It is only necessary to use a file name other than docker if you have (or plan to have) another version of the Docker client installed on your system. To use the Docker client installed by following the instructions in this section, remember to call the docker-1.9.1 binary. To do so, substitute the docker command used in examples in this guide with docker-1.9.1.

4.1.3. Installing the docker Executable on Mac OS X

If you already have the docker binary installed on your system (for example, as a part of the Docker Toolbox), check that it is the correct version (1.9.1) for use with the Docker service provided by the CDK virtual machine by running the following command:

~]$ docker version
Client:
 Version:         1.9.1

[...]

If the version of the docker binary is different from what is required for working with the Docker service provided by the CDK box, or if you do not have the docker binary installed, see the following procedure.

  1. Download the docker-1.9.1 binary from https://get.docker.com/builds/Darwin/x86_64/docker-1.9.1 to a directory of your choice. In this example, the ~/docker directory is used:

    ~]$ mkdir ~/docker
    
    ~]$ cd ~/docker
    
    ~/docker]$ wget https://get.docker.com/builds/Darwin/x86_64/docker-1.9.1
  2. Add the ~/docker directory to the PATH environmental variable, so that the docker-1.9.1 command can be used without specifying its location:

    ~/docker]$ export PATH=$PATH:~/docker
  3. Make the binary executable:

    ~/docker]$ chmod 764 docker-1.9.1
Note

It is only necessary to use a file name other than docker if you have (or plan to have) another version of the Docker client installed on your system. To use the Docker client installed by following the instructions in this section, remember to call the docker-1.9.1 binary. To do so, substitute the docker command used in examples in this guide with docker-1.9.1.

4.1.4. Installing the docker.exe Executable on Windows

If you already have the docker.exe binary installed on your system (for example, as a part of the Docker Toolbox), check that it is the correct version (1.9.1) for use with the Docker service provided by the CDK virtual machine by running the following command (using the Cygwin Bash environment):

~]$ docker version
Client:
 Version:         1.9.1

[...]

If the version of the docker.exe binary is different from what is required for working with the Docker service provided by the CDK box, or if you do not have the docker.exe binary installed, see the following procedure.

  1. Download the docker-1.9.1.exe binary from https://get.docker.com/builds/Windows/x86_64/docker-1.9.1.exe to a folder of your choice.

    Note

    It is only necessary to use a file name other than docker.exe if you have (or plan to have) another version of the Docker client installed on your system. To use the Docker client installed by following the instructions in this section, remember to call the docker-1.9.1.exe binary. To do so, substitute the docker command used in examples in this guide with docker-1.9.1.

  2. Add the C:\Program Files (x86)\docker folder to the PATH environmental variable, so that the docker-1.9.1 command can be used without specifying its location:

    C:\> set PATH=%PATH%;"C:\Program Files (x86)\docker"

4.2. Learning about the Docker Environment

The docker command offers several sub-commands that let you acquire information about the Docker service, the environment it runs in, and available resources. You can also query the service for images and containers it manages and for images that are available to you from the pre-configured registries. By default, the Docker service in CDK can download and use images from both the Docker Hub (docker.io) and the Red Hat Atomic Registry (registry.access.redhat.com).

Use the following commands to obtain information about the Docker service and the working environment.

4.2.1. Verifying the Version of the Docker Service

Run the docker version command to see the version of both the Docker Client and Docker Server:

~]$ docker version
Client:
 Version:         1.9.1
 API version:     1.21
 Package version: docker-1.9.1-25.el7.x86_64
 Go version:      go1.4.2
 Git commit:      78ee77d/1.9.1
 Built:
 OS/Arch:         linux/amd64

Server:
 Version:         1.9.1
 API version:     1.21
 Package version: docker-1.9.1-25.el7.x86_64
 Go version:      go1.4.2
 Git commit:      78ee77d/1.9.1
 Built:
 OS/Arch:         linux/amd64

4.2.2. Displaying Information about the System and Resources

Run the docker info command to see information about the host system (which, in this case, is the virtualized Red Hat Enterprise Linux instance managed by Vagrant), utilization of virtualization resources, basic networking information, and the numbers of managed containerrs and images:

~]$ docker info
Containers: 14
Images: 32
Server Version: 1.9.1
Storage Driver: devicemapper
 Pool Name: VolGroup00-docker--pool
 Pool Blocksize: 524.3 kB
 Base Device Size: 107.4 GB
 Backing Filesystem: xfs
 Data file:
 Metadata file:
 Data Space Used: 2.172 GB
 Data Space Total: 13.6 GB
 Data Space Available: 11.43 GB
 Metadata Space Used: 1.016 MB
 Metadata Space Total: 46.14 MB
 Metadata Space Available: 45.12 MB
 Udev Sync Supported: true
 Deferred Removal Enabled: true
 Deferred Deletion Enabled: true
 Deferred Deleted Device Count: 0
 Library Version: 1.02.107-RHEL7 (2015-12-01)
Execution Driver: native-0.2
Logging Driver: json-file
Kernel Version: 3.10.0-327.13.1.el7.x86_64
Operating System: Red Hat Enterprise Linux Server 7.2 (Maipo)
CPUs: 2
Total Memory: 2.781 GiB
Name: rhel-cdk
ID: PZ3X:6J7V:OF4L:KZRY:XXDT:QXCU:UHGQ:XMWE:EMM5:4POR:CG6D:YF4S

4.3. Learning about Containers and Images

Use the following commands to obtain information about images and containers on your system.

4.3.1. Listing Managed Images

Run the docker images command to display a list of images available in the local registry.

~]$ docker images
REPOSITORY                                                 TAG       IMAGE ID      CREATED      VIRTUAL SIZE
docker.io/prom/haproxy-exporter                            latest    2b168f203700  11 days ago  23.64 MB
registry.access.redhat.com/openshift3/ose-pod              v3.1.1.6  2b96d2bcbc46  2 weeks ago  428 MB
registry.access.redhat.com/openshift3/ose-sti-builder      v3.1.1.6  983aa720a8e7  3 weeks ago  441.9 MB
registry.access.redhat.com/openshift3/ose-deployer         v3.1.1.6  d772a87d1aac  3 weeks ago  441.9 MB
registry.access.redhat.com/openshift3/ose                  v3.1.1.6  88178069a37f  3 weeks ago  441.9 MB
registry.access.redhat.com/openshift3/ose-haproxy-router   v3.1.1.6  5e18f7fbcc6c  3 weeks ago  456.8 MB
registry.access.redhat.com/openshift3/ose-docker-registry  v3.1.1.6  3c272743b20a  3 weeks ago  478.5 MB

4.3.2. Listing Managed Containers

Run the docker ps command to display a list of running containers. Add the --all or -a parameter to list all available containers (not just the running ones). As you can see from the example output below, there are several running containers in CDK immediately after launch. These containers provide some of the services offered by CDK and as such should not be stopped or removed. The example below shows containers with the OpenShift service

Use the --format parameter to specify what information you want displayed about the individual containers (see the docker-ps(1) manual page for a list of available placeholders). For example:

~]$ docker ps --format "table {{.ID}}\t{{.Image}}\t{{.Command}}\t{{.Status}}"
CONTAINER ID  IMAGE                                               COMMAND                 STATUS
ce4817df7620  prom/haproxy-exporter:latest                        "/bin/go-run -haproxy"  Up 55 minutes
e38b37b6e13a  openshift3/ose-docker-registry:v3.1.1.6             "/bin/sh -c 'DOCKER_R"  Up 56 minutes
8abd50d2311f  openshift3/ose-pod:v3.1.1.6                         "/pod"                  Up 56 minutes
6821a60044a8  openshift3/ose-haproxy-router:v3.1.1.6              "/usr/bin/openshift-r"  Up 56 minutes
5312e060116d  openshift3/ose-pod:v3.1.1.6                         "/pod"                  Up 56 minutes
8c94cc0c049b  registry.access.redhat.com/openshift3/ose:v3.1.1.6  "/usr/bin/openshift s"  Up 59 minutes

4.3.3. Displaying Information about Container Resource Usage

Run the docker stats <container> command to display a live output showing resource-usage statistics for a specific running container. For example:

~]$ docker stats openshift
CONTAINER  CPU %  MEM USAGE / LIMIT    MEM %  NET I/O    BLOCK I/O
openshift  0.00%  110.4 MB / 2.986 GB  3.70%  0 B / 0 B  77.24 MB / 3.708 MB

4.3.4. Displaying Detailed Information about Container or Image Configuration

Run the docker inspect <container> command to show low-level information about a container or an image in JSON format. Use the --type parameter to specify whether you want to display information about a container (the default) or an image in case you have containers and images of the same name.

Use the --format parameter to specify what part of the output you want displayed (see the docker-inspect(1) manual page for examples of the output). For example, define the following format to list network ports exposed by the container:

~]$ docker inspect --format='{{.Config.ExposedPorts}}' openshift
map[8443/tcp:{} 53/tcp:{}]

4.4. Getting New Docker-Formatted Container Images

Existing images for creating containers can be either downloaded (pulled) from one of the two pre-configured repositories (the Docker Hub (docker.io) and the Red Hat Atomic Registry (registry.access.redhat.com)) or imported from a local file.

4.4.1. Searching Registries for Images

Run the docker search <search-term> command to search the pre-configured registries for images. For example, to search for images containing the string rhscl in the name or namespace, use the following command:

~]$ docker search rhscl
INDEX        NAME                                                           DESCRIPTION                                     STARS  OFFICIAL  AUTOMAT
docker.io    docker.io/rhscl/mongodb-26-centos7                             A Centos7 based MongoDB v2.6 image for use...   0
redhat.com   registry.access.redhat.com/rhscl/devtoolset-4-toolchain-rhel7  Developer toolset toolchain                     0
redhat.com   registry.access.redhat.com/rhscl/httpd-24-rhel7                Apache HTTP 2.4 Server                          0
redhat.com   registry.access.redhat.com/rhscl/mariadb-100-rhel7             MariaDB 10.0 SQL database server                0
redhat.com   registry.access.redhat.com/rhscl/mongodb-26-rhel7              MongoDB 2.6 NoSQL database server               0
redhat.com   registry.access.redhat.com/rhscl/mysql-56-rhel7                MySQL 5.6 SQL database server                   0
redhat.com   registry.access.redhat.com/rhscl/nginx-16-rhel7                Nginx 1.6 server and a reverse proxy server     0
[...]

4.4.2. Downloading Images from a Registry

Run the docker pull <image> command to download (pull) the specified image to your system for local use. Note that while it is possible to provide just the name of the image, it is better practice to also specify the registry you want to pull from and the namespace in which the particular image is published. The naming convention follows this order: [registry/][namespace/]name.

For example, to pull the image with the toolchain components of the Red Hat Developer Toolset from the Red Hat Atomic Registry, use the following command:

~]$ docker pull registry.access.redhat.com/rhscl/devtoolset-4-toolchain-rhel7
Using default tag: latest
68f6775524af: Download complete
6c3a84d798dc: Download complete
Status: Downloaded newer image for registry.access.redhat.com/rhscl/devtoolset-4-toolchain-rhel7:latest

~]$ docker images registry.access.redhat.com/rhscl/devtoolset-4-toolchain-rhel7
REPOSITORY                                                     TAG     IMAGE ID      CREATED      VIRTUAL SIZE
registry.access.redhat.com/rhscl/devtoolset-4-toolchain-rhel7  latest  68f6775524af  7 weeks ago  365.5 MB

4.4.3. Loading an Image from a File

Run the docker load < file.tar command to load an image from a local file file.tar. By default, the docker pull command loads image data from the standard input. To load an image from a file, use the --input or -i parameter. For example to load the Red Hat Developer Toolset toolchain image that was previously saved to a tar file using the docker save command, use the following command:

~]$ docker load -i devtoolset.tar

4.5. Using Containers

Use the following commands to launch, stop, or remove containers or to run applications from within containers.

4.5.1. Launching a New Container and Running a Command

Run the docker run <image> <command> command to launch a new container from an image and run the specified command. Use the --name parameter to specify a name for the container to prevent the Docker service from assigning a random name to the container. For example, to run the uname -a command (and display its output) in a container created from the Red Hat Developer Toolset toolchain image, use the following command:

~]$ docker run --name devtoolset registry.access.redhat.com/rhscl/devtoolset-4-toolchain-rhel7 uname -a
Linux 22b819dec3f1 3.10.0-327.el7.x86_64 #1 SMP Thu Oct 29 17:29:29 EDT 2015 x86_64 x86_64 x86_64 GNU/Linux

~]$ docker ps -a --format "table {{.ID}}\t{{.Names}}\t{{.Command}}\t{{.Status}}"
CONTAINER ID  NAMES       COMMAND     STATUS
22b819dec3f1  devtoolset  "uname -a"  Exited (0) 2 seconds ago
[...]

4.5.2. Stopping a Container

Run the docker stop <container> command to stop one or more containers. This action tries to gracefully shut down the applications running in the container by sending them the SIGTERM signal (followed by the SIGKILL signal if SIGTERM does not work). For example, to stop the container created in the previous example, use the following command:

~]$ docker stop devtoolset
devtoolset

~]$ docker ps | grep devtoolset

4.5.3. Starting an Existing Container

Use the docker start -i <container> command to run the container stopped in the previous example (the --interactive or -i parameter ensures that the container’s standard output is attached to your current shell — in other words, it ensures that the output of the command executed in the container is displayed):

~]$ docker start -i devtoolset
Linux 22b819dec3f1 3.10.0-327.el7.x86_64 #1 SMP Thu Oct 29 17:29:29 EDT 2015 x86_64 x86_64 x86_64 GNU/Linux

4.5.4. Launching a New Container and Switching to the Container’s Shell

Run the docker run -ti <image> bash command to launch a new container from an image and switch to an interactive shell within the container. The --interactive or -i parameter along with the --tty or -t parameter are used to allocate a pseudo-TTY within which the Bash shell is run. For example:

~]$ docker run -it registry.access.redhat.com/rhscl/devtoolset-4-toolchain-rhel7 bash
bash-4.2$ uname -a
Linux 5e224c8c3878 3.10.0-327.el7.x86_64 #1 SMP Thu Oct 29 17:29:29 EDT 2015 x86_64 x86_64 x86_64 GNU/Linux
bash-4.2$ exit
exit

~]$ docker ps -a --format "table {{.ID}}\t{{.Names}}\t{{.Command}}\t{{.Status}}"
CONTAINER ID  NAMES       COMMAND     STATUS
5e224c8c3878  devtoolset  "uname -a"  Exited (0) 2 seconds ago
[...]

4.5.5. Removing a Container

Run the docker rm <container> command to remove one or more containers, thus freeing the host’s resources. For example, to remove the container created in the previous example, use the following command:

~]$ docker rm devtoolset
devtoolset

~]$ docker ps -a | grep devtoolset

4.6. Additional Resources

  • See the COMMANDS section of the docker(1) manual page for a complete list of available docker commands and detailed descriptions of their function.
  • See the Getting Started with Containers guide for detailed information about the use and management of containers on the Red Hat Enterprise Linux and Red Hat Atomic platforms.

Chapter 5. Using OpenShift Enterprise

When you initialize the CDK Vagrant box using the rhel-ose Vagrantfile, which is provided as a part of Red Hat Container Tools (located in cdk/components/rhel/rhel-ose/Vagrantfile in the ZIP file), the launched virtual machine automatically provisions an instance of OpenShift Enterprise. (See the CDK Installation Guide for additional information on how to launch CDK with a specific Vagrantfile.)

Note

OpenShift Enterprise is a Platform as a Service (PaaS) offering by Red Hat that extends the functionality of the Docker service and the Kubernetes container orchestration tool to provide a powerful and easy-to-use platform for building, deploying, and orchestrating multi-container applications and services.

Command-line usage of the OpenShift service provided by the CDK box is possible both from within the virtual machine and from the host machine. This section provides examples of basic usage of the oc command. Note that you can also administer a subset of OpenShift features using its web user interface, which is accesible at https://10.1.2.2:8443/console.

See also the OpenShift Enterprise Developer Guide for detailed instructions on how to set up and configure a workstation to develop and deploy applications in an OpenShift cloud environment with a command-line interface (CLI) and the web console.

5.1. Preparing Your Host System for Using OpenShift

To use the oc command on your host system to interact with the OpenShift service running inside the CDK virtual machine, you need to obtain and install the oc executable.

If you intend to use OpenShift (and the oc command) only from within the CDK virtual machine, no preparation is required — the oc command is installed in the CDK box by default.

5.1.1. Obtaining the oc Executable

Download an archive with the executable for your operating system (Linux, Mac OS X, or Windows) from the Red Hat Customer Portal: Red Hat OpenShift Enterprise (you need to log in to the Customer Portal and have an active OpenShift Enterprise subscription to be able to access the download page).

Note that downloading this archive is not necessary if you use Red Hat Enterprise Linux as your host system because the oc executable can be installed from system repositories using yum. See Installing the oc Executable on Red Hat Enterprise Linux for details.

5.1.2. Installing the oc Executable on Red Hat Enterprise Linux

Install the atomic-openshift-clients package, which provides the oc executable. The package is available from the rhel-7-server-ose-3.1-rpms (Red Hat OpenShift Enterprise 3.1) repository. Use the following command as root to enable the repository (you need to have an active OpenShift Enterprise subscription to be able to access the repository):

~]# subscription-manager repos --enable=rhel-7-server-ose-3.1-rpms

Install the atomic-openshift-clients package using the following command as root:

~]# yum install -y atomic-openshift-clients

5.1.3. Installing the oc Executable on Fedora or Other Linux Distribution

Unpack the oc executable from the archive obtained using instructions in Obtaining the oc Executable to a directory of your choice and add that directory to your PATH, so that the oc command can be used without specifying its location.

For example, to unpack the executable to the ~/openshift directory and configure the PATH variable accordingly, run the following commands from the directory to which you downloaded the archive:

~]$ mkdir ~/openshift

~]$ tar xvzf oc-3.1.1.6-linux.tar.gz --strip=8 -C ~/openshift
mnt/redhat/staging-cds/ose-clients-3.1.1.6/usr/share/atomic-openshift/linux/oc

~]$ export PATH=$PATH:~/openshift

5.1.4. Installing the oc Executable on Mac OS X

Unpack the oc executable from the archive obtained using instructions in Obtaining the oc Executable to a directory of your choice and add that directory to your PATH, so that the oc command can be used without specifying its location.

For example, to unpack the executable to the ~/openshift directory and configure the PATH variable accordingly, run the following commands from the directory to which you downloaded the archive:

~]$ mkdir ~/openshift

~]$ tar xvzf oc-3.1.1.6-macosx.tar.gz --strip=8 -C ~/openshift
mnt/redhat/staging-cds/ose-clients-3.1.1.6/usr/share/atomic-openshift/macosx/oc

~]$ export PATH=$PATH:~/openshift

5.1.5. Installing the oc.exe Executable on Windows

Unpack the oc.exe executable from the archive obtained using instructions in Obtaining the oc Executable to a folder of your choice and add that folder to your PATH, so that the oc command can be used without specifying its location.

For example, to unpack the executable to the C:\Program Files (x86)\openshift folder and configure the PATH variable accordingly, run the following commands (using the Command Prompt or other terminal emulator) from the folder to which you downloaded the archive:

C:\Downloads> mkdir C:\Program Files (x86)\openshift

C:\Downloads> cd C:\Program Files (x86)\openshift

C:\Program Files (x86)\openshift> unzip -j oc-3.1.1.6-windows.zip
Archive:  oc-3.1.1.6-windows.zip
  inflating: oc.exe

C:\Program Files (x86)\openshift> set PATH=%PATH%;"C:\Program Files (x86)\openshift"

5.2. Verifying the OpenShift Installation

Upon initializing the CDK Vagrant box using the rhel-ose Vagrantfile, the following information is output about the OpenShift service that has been provisioned for you:

You can now access the OpenShift console on: https://10.1.2.2:8443/console

To use OpenShift CLI, run:
$ vagrant ssh
$ oc login 10.1.2.2:8443

Configured users are (<username>/<password>):
openshift-dev/devel
admin/admin

If you have the oc client library on your host, you can also login from your host.

The automatically provisioned instance of OpenShift Enterprise in CDK is provided in the form of a container. You can check that the OpenShift container is installed and running by examining the output of the docker ps command:

~]$ docker ps
CONTAINER ID  IMAGE      COMMAND                 CREATED      STATUS      PORTS  NAMES
...
ddb2d13604ef  openshift  "/usr/bin/openshift s"  2 hours ago  Up 2 hours         openshift

You can also run a health check to determine whether OpenShift is running properly by querying its network interface using the curl command:

~]$ curl -k https://10.1.2.2:8443/healthz
ok

5.3. Displaying Information about the OpenShift Service

The command-line interface of OpenShift is accessed using the oc command. This command has a number of subcommands that help to interact with various features of the OpenShift service. This section describes how to use the oc command to gather basic information about the current OpenShift instance.

5.3.1. Checking the Version of OpenShift and Kubernetes

Use the oc version command to display the version of OpenShift Enterprise and the Kubernetes service currently in use:

~]$ oc version
oc v3.1.0.4-16-g112fcc4
kubernetes v1.1.0-origin-1107-g4c8e6f4

5.4. Logging in and out of the OpenShift Server

Use the oc login command to log into specific user profiles. Upon start up, the CDK box logs you in automatically to the openshift-dev account.

5.4.1. Logging in to the OpenShift Server

Use the oc login command to log into the OpenShift server. If you want top log in from your hosty system, you to specify a host address (10.1.2.2:8443). The command asks for the username and password interactively, but you can also supply this information on the command line using the -u (--username) and -p (--password) options respectively. For example, to log into the default OpenShift instance in CDK from your host system, use the following command:

~]$ oc login -u openshift-dev -p devel https://10.1.2.2:8443
The server uses a certificate signed by an unknown authority.
You can bypass the certificate check, but any data you send to the server could be intercepted by others.
Use insecure connections? (y/n): y

Authentication required for https://10.1.2.2:8443 (openshift)
Username: openshift-dev
Password:
Login successful.

You have access to the following projects and can switch between them with 'oc project <projectname>':

  * sample-project (current)

Using project "sample-project".
Welcome! See 'oc help' to get started.

Use the oc whoami command to check the user account to which you are currently logged:

~]$ oc whoami
openshift-dev

5.4.2. Viewing Current OpenShift CLI Configuration

To display the configuration values for the command-line environment, use the oc config view. For example, to show the part of the configuration pertaining to the default user name (openshift-dev), issue the following command:

~]$ oc config view | grep -A2 "name: openshift-dev"
- name: openshift-dev/10-1-2-2:8443
  user:
    token: THdHS4sw1qgzs95CnCf5ic6D8eOrZss1aT5jyGOmd2w

5.4.3. Logging out of the OpenShift Server

To log out, use the oc logout command:

~]$ oc logout
Logged "openshift-dev" out on "https://10.1.2.2:8443"

5.5. Working with OpenShift Projects

In OpenShift, projects are used to organize and manage applications by groups of users. Individual projects keep their content separated from each other, and individual users need to be granted access to projects. Upon start up, the CDK box automatically creates the sample-project project.

5.5.1. Creating a New OpenShift Project

Use the oc new-project command to create a new project on the OpenShift server you are currently logged in to. The following example uses the optional --display-name option to set a user-friendly name for the project:

~]$ oc new-project testing --display-name="Test Project"
Now using project "testing" on server "https://127.0.0.1:8443".

You can add applications to this project with the 'new-app' command. For example, try:

    $ oc new-app centos/ruby-22-centos7~https://github.com/openshift/ruby-hello-world.git

to build a new hello-world application in Ruby.

5.5.2. Switching to a Different OpenShift Project

Use the oc project <project-name> command to switch to another project on the OpenShift server you are currently logged in to. The following switches to the default sample-project project:

~]$ oc project sample-project
Now using project "sample-project" on server "https://10.1.2.2:8443".

5.5.3. Listing Available Projects

To list projects available on the server and their status, use the oc get projects command. Note that the oc get command can be used to display information about a number of other resources besides projects (pods, builds, services, etc.). In the following example, only the project created in the preceeding example is shown:

~]$ oc get project
NAME      DISPLAY NAME   STATUS
testing   Test Project   Active

5.5.4. Displaying Status Information about the Currently Used Project

Run the oc status command to display information about the currently used project and about activities (services, builds, deployments, etc.) within that project. When executed in a new (empty) project, the output looks like the following:

~]$ oc status
In project Test Project (testing) on server https://10.1.2.2:8443

You have no services, deployment configs, or build configs.
Run 'oc new-app' to create an application.

Alternatively, you can also use the oc project command to display project information:

~]$ oc project
Using project "testing" from context named "testing/10-1-2-2:8443/openshift-dev" on server "https://10.1.2.2:8443".

5.5.5. Deleting a Project

To remove a project from the server, use the oc delete project command and specify the name of the project you want deleted. To remove all projects, include the --all option. Note that the oc delete command can be used to delete other resources (pods, services, etc.) as well. For example, to delete the project created in this section, run the following command:

~]$ oc delete project testing
project "testing" deleted

5.6. Working with OpenShift Templates

A template in OpenShift is a text file (in the JSON or YAML format) that defines a set of objects. The object definitions, such as services or build configurations, can be parametrized. Templates can be processed to create the objects they describe and thus populate your current project.

To get you quickly started with application development, OpenShift offers a number of basic templates, which are included in the global openshift project. In order to use these templates as the foundation block of a new application, they need to be downloaded from the openshift project and subsequently uploaded to your current project. You can also create a new application (using the oc new-app command) directly from a template.

5.6.1. Listing Available Templates

To display the templates available in a project, issue the oc get templates command and use the -n option to specify the project from which you wish to list the templates. For example, to list the templates available in the global openshift project, run:

~]$ oc get templates -n openshift
NAME                                DESCRIPTION                        PARAMETERS     OBJECTS
cakephp-example                     An example CakePHP application...  15 (8 blank)   5
cakephp-mysql-example               An example CakePHP application...  16 (3 blank)   7
eap64-basic-s2i                     Application template for EAP 6...  12 (3 blank)   5
eap64-mysql-persistent-s2i          Application template for EAP 6...  34 (16 blank)  10
jws30-tomcat7-mysql-persistent-s2i  Application template for JWS M...  28 (11 blank)  10
nodejs-example                      An example Node.js application...  12 (8 blank)   5
nodejs-mongodb-example              An example Node.js application...  13 (3 blank)   7

5.6.2. Downloading an InstantApp Template

To obtain a template definition file, which can be used for uploading to your project, use the oc get templates command and specify the project in which the template is located (using the -n or --namespace option), choose the format in which you wish to store the template (typically JSON or YAML — use the -o or --output option), and supply the name of the requested template. Note that by default, the oc get command outputs the requested data to the standard output. To store the template in a file, redirect the output of the command to a file.

For example, to download the nodejs-mongodb-example template from the global openshift project and save it in the JSON format on your local syastem, use the following command:

~]$ oc get templates -o json -n openshift nodejs-mongodb-example \ > nodejs-mongodb-example.json

~]$ ls
nodejs-mongodb-example.json

5.6.3. Modifying the Namespace (Project Name)

When you download an InstantApp template from the default openshift project, the namespace (project name) in the template is set to openshift. To be able to upload the template to your project, you need to modify the template accordingly. If you do not do that, the upload fails with the following error message:

~]$ oc create -f nodejs-mongodb-example.json -n testing
the namespace from the provided object "openshift" does not match the namespace "testing". You must pass '--namespace=openshift' to perform this operation.

To modify the namespace, edit the file using a text editor, such as vi, and in the metadata section, replace the value of the namespace parameter with the name of your project. For example, to use the name testing, the beginning of the nodejs-mongodb-example.json template file would look like this:

{
    "kind": "Template",
    "apiVersion": "v1",
    "metadata": {
        "name": "nodejs-mongodb-example",
        "namespace": "testing",
[...]

5.6.4. Uploading a Template to the Current Project

For a template to be available for use in your project, it must be first uploaded to it. Use the oc create command to do this and specify the template file using the -f or --filename option. For example, to upload the nodejs-mongodb-example InstantApp template obtained from the openshift project, run the following command:

~]$ oc create -f nodejs-mongodb-example.json
template "nodejs-mongodb-example" created

To verify that the template has been successfully uploaded, use the oc get templates command. Optionally, you can specify the namespace from which you wish to list by using the -n or --namespace option. By default, templates from the currently used project are listed:

~]$ oc get templates
NAME                     DESCRIPTION                                              PARAMETERS     OBJECTS
nodejs-mongodb-example   An example Node.js application with a MongoDB database   11 (3 blank)   7

5.6.5. Listing Template Parameters

To list the parameters that a template specifies along with short descriptions and predefined values, use the oc process command with the --parameters option. For example, to list the parameters used by the nodejs-mongodb-example template, use the following command:

~]$ oc process --parameters nodejs-mongodb-example
NAME                     DESCRIPTION                              GENERATOR   VALUE
SOURCE_REPOSITORY_URL    The URL of the repository with your...               https://github.com/openshift/nodejs-ex.git
SOURCE_REPOSITORY_REF    Set this to a branch name, tag or ot...
CONTEXT_DIR              Set this to the relative path to you...
APPLICATION_DOMAIN       The exposed hostname that will route...
GITHUB_WEBHOOK_SECRET    A secret string used to configure th...  expression  [a-zA-Z0-9]{40}
GENERIC_WEBHOOK_SECRET   A secret string used to configure th...  expression  [a-zA-Z0-9]{40}
DATABASE_SERVICE_NAME    Database service name                                         mongodb
DATABASE_USER            Username for MongoDB user that will...   expression  user[A-Z0-9]{3}
DATABASE_PASSWORD        Password for the MongoDB user            expression  [a-zA-Z0-9]{16}
DATABASE_NAME            Database name                                        sampledb
DATABASE_ADMIN_PASSWORD  Password for the database admin user...  expression  [a-zA-Z0-9]{16}

5.6.6. Creating Objects from a Template

To process a template and use it to create the objects it defines in your project, use a combination of the oc process and oc create commands. The template processed by the oc process command can be piped to the oc create command.

Note that in most cases, the template parameters need to be modified, so that the resulting application can be useful in a real-world scenario. To modify the template parameters when creating the objects, use the -v or --value option.

For example, to create objects using the nodejs-mongodb-example template and to set a different source repository for the application (the original repository would need to be forked to the repository specified on the command line), use the following combination of commands:

~]$ oc process nodejs-mongodb-example \
-v SOURCE_REPOSITORY_URL=https://github.com/username/nodejs-ex.git | \
oc create -f -
service "nodejs-mongodb-example" created
route "nodejs-mongodb-example" created
imagestream "nodejs-mongodb-example" created
buildconfig "nodejs-mongodb-example" created
deploymentconfig "nodejs-mongodb-example" created
service "mongodb" created
deploymentconfig "mongodb" created

In the above example, substitute username for the name of the GitHub account into which the original repository was forked.

5.7. Additional Resources

  • See the output of the oc help command for an overview of all oc subcommands available. More detailed help for individual subcommands can be accessed by running oc help [subcommand].
  • See the OpenShift Enterprise CLI Reference for detailed descriptions of the command-line user interface used to interact with OpenShift Enterprise.
  • See the OpenShift Enterprise Developer Guide for detailed instructions and examples to help developers configure a workstation to develop and deploy applications in an OpenShift Enterprise cloud environment with a command-line interface.

Chapter 6. Deploying an Application on OpenShift

This section describes how to use OpenShift to create containerized applications and deploy them on an OpenShift cluster. The examples in this section use only basic features of the OpenShift service and are for demonstration purposes only. See the CDK Developer Guide (to be published) for more in-depth descriptions.

6.1. Deploying an InstantApp Template as a New Application

In this example, an InstantApp template available from the default openshift project is used to create and deploy a web application. The definition of the template sets all necessary configuration options. A good way to experiment with OpenShift deployments is to clone the example’s repository and modify different parts of the defined template.

6.1.1. Creating a New OpenShift Application from a Template

To use a template to directly create a new application, run the oc new-app command with the --template option specifying the template you want to use as the basis for your application. For example, to use the nodejs-example InstantApp template, run the following command:

~]$ oc new-app --template=nodejs-example
--> Deploying template nodejs-example in project openshift for "nodejs-example"
     With parameters:
      Memory Limit=512Mi
      Git Repository URL=https://github.com/openshift/nodejs-ex.git
      Git Reference=
      Context Directory=
      Application Hostname=
      GitHub Webhook Secret=UKWP4bVymgjXcNMVnHIdaVeaORt3NMPuyqAEHhLv # generated
      Generic Webhook Secret=wabGtSM7g5eSykRuH5aCskWKdFOXB0UxyNNrnQyr # generated
      Database Service Name=
      MongoDB Username=
      MongoDB Password=
      Database Name=
      Database Administrator Password=
--> Creating resources with label app=nodejs-example ...
    Service "nodejs-example" created
    Route "nodejs-example" created
    ImageStream "nodejs-example" created
    BuildConfig "nodejs-example" created
    DeploymentConfig "nodejs-example" created
--> Success
    Build scheduled for "nodejs-example" - use the logs command to track its progress.
    Run 'oc status' to view your app.

6.1.2. Monitoring Deployment Progress

To monitor the progress of the deployment, use the oc status command, optionally with the -v (--verbose) parameter to display information about potential warnings:

~]$ oc status -v
In project OpenShift sample project (sample-project) on server https://127.0.0.1:8443

svc/nodejs-example - 172.30.142.222:8080
  dc/nodejs-example deploys imagestreamtag/nodejs-example:latest <-
    bc/nodejs-example builds https://github.com/openshift/nodejs-ex.git with openshift/nodejs:0.10
      #1 build running for 27 seconds
    #1 deployment waiting on image or update
  exposed by route/nodejs-example

Warnings:
  * The image trigger for dc/nodejs-example will have no effect until imagestreamtag/nodejs-example:latest is imported or created by a build.

View details with 'oc describe <resource>/<name>' or list everything with 'oc get all'.

6.1.3. Displaying Information about a Deployed Service

The application is automatically deployed when the build completes. Use the oc describe command to display information about different parts of the application (or use the oc get all command to display all information at once).

To see summary information about the service, use:

~]$ oc describe svc/nodejs-example
Name:                   nodejs-example
Namespace:              sample-project
Labels:                 app=nodejs-example,template=nodejs-example
Selector:               name=nodejs-example
Type:                   ClusterIP
IP:                     172.30.142.222
Port:                   web     8080/TCP
Endpoints:              172.17.0.2:8080
Session Affinity:       None
No events.

To display information about the route established for the application, use:

~]$ oc describe route/nodejs-example
Name:                   nodejs-example
Created:                46 minutes ago
Labels:                 app=nodejs-example,template=nodejs-example
Annotations:            openshift.io/generated-by=OpenShiftNewApp
                        openshift.io/host.generated=true
Host:                   nodejs-example-sample-project.rhel-cdk.10.1.2.2.xip.io
Path:                   <none>
Service:                nodejs-example
TLS Termination:        <none>
Insecure Policy:        <none>

The above command shows that the deployed application can be accessed at nodejs-example-sample-project.rhel-cdk.10.1.2.2.xip.io (the URL is made available through the external xip.io DNS service).

You can point a web browser from your host system at this address to see the page generated by the application. To check whether the application is running properly from the command line, either use a text-mode browser like lynx or download the page using curl:

~]$ curl nodejs-example-sample-project.rhel-cdk.10.1.2.2.xip.io 2> /dev/null | grep '<h1>'
            <h1>Welcome to your Node.js application on OpenShift</h1>

6.1.4. Learning about Service Images and Containers

To check the Docker images and containers that form the application, use the docker images and docker ps commands:

~]$ docker images
REPOSITORY                                        TAG     IMAGE ID      CREATED      VIRTUAL SIZE
172.30.254.28:5000/sample-project/nodejs-example  latest  bc19f3f7dd86  2 hours ago  432.6 MB
172.30.254.28:5000/sample-project/nodejs-example  <none>  bc19f3f7dd86  2 hours ago  432.6 MB

[...]

~]$ docker ps
CONTAINER ID  IMAGE                                                        COMMAND                 CREATED      STATUS      NAMES
bcafafb013ce  172.30.254.28:5000/sample-project/nodejs-example@sha256:...  "container-entrypoint"  2 hours ago  Up 2 hours  k8s_nodejs-example.27445d76_nodejs-example-1-hdq11_sample-project_e5c69b57-0496-11e6-907d-525400806d1b_3e6e6b39
d4f52a47cb10  openshift3/ose-pod:v3.1.1.6                                  "/pod"                  2 hours ago  Up 2 hours  k8s_POD.5983fd1a_nodejs-example-1-hdq11_sample-project_e5c69b57-0496-11e6-907d-525400806d1b_b3dee3ea

[...]

6.2. Deploying a 'Hello World' Application Using Node.js

In this example, a very simple Node.js web application is created. The application is defined using a minimalistic build strategy that is automatically downloaded from a Git repository (in this case, GitHub is used). The built application is deployed on top of a Node.js container pulled from the Red Hat Atomic Registry.

6.2.1. Preparing the Application Source Code

Create a new repository on GitHub. For the purposes of this example, we will assume that the created repository has the following URL: http://github.com/example/nodejs-hello-world.git. Then upload a basic Node.js application to the root directory of the repository. Name the file helloworld.js.

var http = require('http');

var server = http.createServer(function(req, res) {
  res.writeHead(200);
  res.end('Hello World');
});
server.listen(8080);

The application creates an HTTP server listening on port 8080 and prints Hello World when accessed. Download the helloword.js file.

6.2.2. Preparing the Definition of an OpenShift Application

Upload the following minimal definition of a Node.js OpenShift application to the GitHub repository. Name the file package.json. Based on the name of the file, OpenShift automatically selects the appropriate builder (nodejs, in this case).

{
  "name": "nodejs-hello-world",
  "version": "0.0.1",
  "description": "Node.js Hello World for OpenShift 3",
  "main": "helloworld.js", 1
  "dependencies": {
    "ejs": "^2.4.1", 2
    "express": "^4.13.4"
  },
  "scripts": {
    "start": "node helloworld.js" 3
  },
  "repository": {
    "type": "git",
    "url": "http://github.com/rkratky/nodejs-hello-world.git"
  }
}
1
Application source file
2
Required build dependencies—​automatically supplied by npm (Node.js package manager)
3
Command to execute

Download the package.json file.

6.2.3. Creating a New OpenShift Application

To create a new application in OpenShift, use the oc new-app command. OpenShift automatically performs the following steps:

  1. downloads required dependencies, including specified Docker-formatted container images,
  2. pulls latest source code and application definition from the specified location (a Git repository, in this case),
  3. builds the application source code,
  4. builds a container with the resulting application,
  5. deploys the application container.

In this example, the required Node.js container image from the Red Hat Atomic Registry is specified along with the URL of the Git repository:

~]$ oc new-app registry.access.redhat.com/openshift3/nodejs-010-rhel7~https://github.com/rkratky/nodejs-hello-world.git
--> Found Docker image 92eee82 (6 weeks old) from registry.access.redhat.com for "registry.access.redhat.com/openshift3/nodejs-010-rhel7"
    * An image stream will be created as "nodejs-010-rhel7:latest" that will track the source image
    * A source build using source code from https://github.com/rkratky/nodejs-hello-world.git will be created
      * The resulting image will be pushed to image stream "nodejs-hello-world:latest"
      * Every time "nodejs-010-rhel7:latest" changes a new build will be triggered
    * This image will be deployed in deployment config "nodejs-hello-world"
    * Port 8080/tcp will be load balanced by service "nodejs-hello-world"
--> Creating resources with label app=nodejs-hello-world ...
    ImageStream "nodejs-010-rhel7" created
    ImageStream "nodejs-hello-world" created
    BuildConfig "nodejs-hello-world" created
    DeploymentConfig "nodejs-hello-world" created
    Service "nodejs-hello-world" created
--> Success
    Build scheduled for "nodejs-hello-world" - use the logs command to track its progress.
    Run 'oc status' to view your app.

6.2.4. Monitoring Build Progress

Use the oc describe build command to display information about the build currently in progress:

~]$ oc describe build
Name:           nodejs-hello-world-1
Created:        35 seconds ago
Labels:         app=nodejs-hello-world,buildconfig=nodejs-hello-world,openshift.io/build-config.name=nodejs-hello-world
Annotations:    openshift.io/build.number=1
                openshift.io/build.pod-name=nodejs-hello-world-1-build
Build Config:   nodejs-hello-world
Started:        2016-04-18 07:05:25 -0400 EDT
Duration:       running for 25s
Build Pod:      nodejs-hello-world-1-build
Strategy:       Source
URL:            https://github.com/rkratky/nodejs-hello-world.git
From Image:     DockerImage registry.access.redhat.com/openshift3/nodejs-010-rhel7:latest
Output to:      ImageStreamTag nodejs-hello-world:latest
Push Secret:    builder-dockercfg-9000s
Status:         Running
Events:
  FirstSeen     LastSeen    Count   From                SubobjectPath                      Reason     Message
  ─────────    ────────   ─────   ────               ─────────────                     ──────     ───────
  34s           34s         1       {scheduler }                                           Scheduled  Successfully assigned nodejs-hello-world-1-build to rhel-cdk
  32s           32s         1       {kubelet rhel-cdk}  implicitly required container POD  Pulled     Container image "openshift3/ose-pod:v3.1.1.6" already present on machine
  30s           30s         1       {kubelet rhel-cdk}  implicitly required container POD  Created    Created with docker id 462325c7c721
  29s           29s         1       {kubelet rhel-cdk}  implicitly required container POD  Started    Started with docker id 462325c7c721
  29s           29s         1       {kubelet rhel-cdk}  spec.containers{sti-build}         Pulled     Container image "openshift3/ose-sti-builder:v3.1.1.6" already present on machine
  27s           27s         1       {kubelet rhel-cdk}  spec.containers{sti-build}         Created    Created with docker id f5bcba8891c3
  26s           26s         1       {kubelet rhel-cdk}  spec.containers{sti-build}         Started    Started with docker id f5bcba8891c3

To see the build logs, use the oc logs command and specify the build you are interested in:

~]$ oc logs build/nodejs-hello-world-1
---> Installing application source
---> Building your Node application from source
E0418 09:17:59.264104  1 util.go:91] npm info it worked if it ends with ok
E0418 09:17:59.265357  1 util.go:91] npm info using npm@2.14.13
E0418 09:17:59.265366  1 util.go:91] npm info using node@v0.10.40
E0418 09:18:00.697173  1 util.go:91] npm WARN package.json nodejs-hello-world@0.0.1 No license field.
E0418 09:18:00.720236  1 util.go:91] npm info preinstall nodejs-hello-world@0.0.1
E0418 09:18:00.828498  1 util.go:91] npm info attempt registry request try #1 at 09:18:00

[...]

6.2.5. Displaying Information about the Deployed Service

Use the oc describe command and specify the service you are interested in to show summary information about the created service:

]$ oc describe svc/nodejs-hello-world
Name:              nodejs-hello-world
Namespace:         sample-project
Labels:            app=nodejs-hello-world
Selector:          app=nodejs-hello-world,deploymentconfig=nodejs-hello-world
Type:              ClusterIP
IP:                172.30.166.144
Port:              8080-tcp        8080/TCP
Endpoints:         172.17.0.4:8080
Session Affinity:  None
No events.

Similarly, you can specify the deployment to show information about it, including the containers that have been created and deployed for the application:

~]$ oc describe dc
Name:           nodejs-hello-world
Created:        2 minutes ago
Labels:         app=nodejs-hello-world
Annotations:    openshift.io/generated-by=OpenShiftNewApp
Latest Version: 1
Triggers:       Config, Image(nodejs-hello-world@latest, auto=true)
Strategy:       Rolling
Template:
  Selector:     app=nodejs-hello-world,deploymentconfig=nodejs-hello-world
  Replicas:     1
  Containers:
  NAME                  IMAGE                                                                                                                           ENV
  nodejs-hello-world    172.30.91.119:5000/sample-project/nodejs-hello-world@sha256:d97a0c44759c93b4231691813c12b5d2975c78fbee028f6c0091d97ed3816678
Deployment #1 (latest):
  Name:         nodejs-hello-world-1
  Created:      2 minutes ago
  Status:       Complete
  Replicas:     1 current / 1 desired
  Selector:     app=nodejs-hello-world,deployment=nodejs-hello-world-1,deploymentconfig=nodejs-hello-world
  Labels:       app=nodejs-hello-world,openshift.io/deployment-config.name=nodejs-hello-world
  Pods Status:  1 Running / 0 Waiting / 0 Succeeded / 0 Failed
No events.

6.2.6. Testing the Running Application

To verify that the deployed HTTP server works correctly and serves the message specified in the application source code, you can use, for example, the curl tool:

~]$ curl 172.17.0.4:8080
Hello World

The IP address is shown, for example, in the description of the deployed service or pod. Use the oc get pods to list all pods:

~]$ oc get pods
NAME                         READY   STATUS      RESTARTS   AGE
nodejs-hello-world-1-1b5xi   1/1     Running     0          2m
nodejs-hello-world-1-build   0/1     Completed   0          2m

Use the name of the pod to display its description and grep for its IP address:

~]$ oc describe pod/nodejs-hello-world-1-1b5xi | grep IP
IP:                             172.17.0.4

6.3. Additional Resources

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