Chapter 6. Using .NET Core 3.1 on OpenShift Container Platform
6.1. Installing .NET Core image streams
To install .NET Core image streams, use image stream definitions from s2i-dotnetcore with the OpenShift Client (oc) binary. Image streams can be installed from Linux, Mac, and Windows. A script enables you to install, update or remove the image streams.
You can define .NET Core image streams in the global openshift namespace or locally in a project namespace. Sufficient permissions are required to update the openshift namespace definitions.
Obtaining the RHEL 7 image streams requires authentication against the registry.redhat.io server using subscription credentials. These credentials are configured by adding a pull secret to the OpenShift namespace.
6.1.1. Installing image streams using OpenShift Client
You can use OpenShift Client (oc) to install .NET Core image streams.
Prerequisites
- An existing pull secret must be present in the namespace. If no pull secret is present in the namespace. Add one by following the instructions in the Red Hat Container Registry Authentication guide.
Procedure
List the available .NET Core image streams:
$ oc describe is dotnet
The output shows installed images. If no images are installed, the
Error from server (NotFound)message is displayed.Install the .NET Core image streams:
$ oc create -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/dotnet_imagestreams.json
When .NET Core image streams are already installed, you can include newer versions by running:
$ oc replace -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/dotnet_imagestreams.json
6.1.2. Installing image streams on Linux and macOS
You can use this script to install, upgrade, or remove the image streams on Linux and macOS.
Procedure
Download the script.
On Linux use:
$ wget https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/install-imagestreams.sh
On Mac use:
$ curl https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/install-imagestreams.sh -o install-imagestreams.sh
Make the script executable:
$ chmod +x install-imagestreams.sh
Log in to the OpenShift cluster:
$ oc login
Install image streams and add a pull secret for authentication against the
registry.redhat.io:./install-imagestreams.sh --os rhel7 [--user subscription_username --password subscription_password]
Replace subscription_username with the name of the user, and replace subscription_password with the user’s password. The credentials may be omitted if you do not plan to use the RHEL7-based images.
If the pull secret is already present, the
--userand--passwordarguments are ignored.
Additional information
-
./install-imagestreams.sh --help
6.1.3. Installing image streams on Windows
You can use this script to install, upgrade, or remove the image streams on Windows.
Procedure
Download the script.
Invoke-WebRequest https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/install-imagestreams.ps1 -UseBasicParsing -OutFile install-imagestreams.ps1
Log in to the OpenShift cluster:
$ oc login
Install image streams and add a pull secret for authentication against the
registry.redhat.io:./install-imagestreams.sh --OS rhel7 [-User subscription_username -Password subscription_password]
Replace subscription_username with the name of the user, and replace subscription_password with the user’s password. The credentials may be omitted if you do not plan to use the RHEL7-based images.
If the pull secret is already present, the
-Userand-Passwordarguments are ignored.
The PowerShell ExecutionPolicy may prohibit executing this script. To relax the policy, run Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass -Force.
Additional information
-
Get-Help .\install-imagestreams.ps1
6.2. Deploying applications from source using oc
The following example demonstrates how to deploy the example-app application using oc, which is in the app folder on the dotnetcore-3.1 branch of the redhat-developer/s2i-dotnetcore-ex GitHub repository:
Procedure
Create a new OpenShift project:
$ oc new-project sample-projectAdd the ASP.NET Core application:
$ oc new-app --name=example-app 'dotnet:3.1~https://github.com/redhat-developer/s2i-dotnetcore-ex#dotnetcore-3.1' --build-env DOTNET_STARTUP_PROJECT=appTrack the progress of the build:
$ oc logs -f bc/example-appView the deployed application once the build is finished:
$ oc logs -f dc/example-appThe application is now accessible within the project.
Optional: Make the project accessible externally:
$ oc expose svc/example-appObtain the shareable URL:
$ oc get routes
6.3. Deploying applications from binary artifacts using oc
You can use .NET Core Source-to-Image (S2I) builder image to build applications using binary artifacts that you provide.
Prerequisites
Published application.
For more information, see
Procedure
Create a new binary build:
$ oc new-build --name=my-web-app dotnet:3.1 --binary=trueStart the build and specify the path to the binary artifacts on your local machine:
$ oc start-build my-web-app --from-dir=bin/Release/netcoreapp3.1/publish
Create a new application:
$ oc new-app my-web-app
6.4. Using Jenkins slave
The OpenShift Container Platform Jenkins image provides auto-discovery of the .NET Core 3.1 slave image (dotnet-31).
For auto-discovery to work, you need to add a Jenkins slave ConfigMap yaml file to the project.
Procedure
Change to the project where Jenkins is (or will be) deployed:
$ oc project _project-name_
Create a
dotnet-jenkins-slave.yamlfile:NoteThe value used for the <serviceAccount> element is the account used by the Jenkins slave. If no value is specified, the
defaultservice account is used.kind: ConfigMap apiVersion: v1 metadata: name: dotnet-jenkins-slave-31 labels: role: jenkins-slave data: dotnet31: |- <org.csanchez.jenkins.plugins.kubernetes.PodTemplate> <inheritFrom></inheritFrom> <name>dotnet-31</name> <instanceCap>2247483647</instanceCap> <idleMinutes>0</idleMinutes> <label>dotnet-31</label> <serviceAccount>jenkins</serviceAccount> <nodeSelector></nodeSelector> <volumes/> <containers> <org.csanchez.jenkins.plugins.kubernetes.ContainerTemplate> <name>jnlp</name> <image>registry.access.redhat.com/dotnet/dotnet-31-jenkins-slave-rhel7:latest</image> <privileged>false</privileged> <alwaysPullImage>true</alwaysPullImage> <workingDir>/tmp</workingDir> <command></command> <args>${computer.jnlpmac} ${computer.name}</args> <ttyEnabled>false</ttyEnabled> <resourceRequestCpu></resourceRequestCpu> <resourceRequestMemory></resourceRequestMemory> <resourceLimitCpu></resourceLimitCpu> <resourceLimitMemory></resourceLimitMemory> <envVars/> </org.csanchez.jenkins.plugins.kubernetes.ContainerTemplate> </containers> <envVars/> <annotations/> <imagePullSecrets/> <nodeProperties/> </org.csanchez.jenkins.plugins.kubernetes.PodTemplate>Import the configuration into the project:
$ oc create -f dotnet-jenkins-slave.yaml
The slave image can now be used.
Example
The following example shows a Jenkins pipeline added to OpenShift Container Platform. Note that when a Jenkins pipeline is added and no Jenkins master is running, OpenShift automatically deploys a master. See OpenShift Container Platform and Jenkins for additional information about deploying and configuring a Jenkins server instance.
In the example steps, the BuildConfig yaml file includes a simple Jenkins pipeline configured using the dotnet-31 Jenkins slave. There are three stages in the example BuildConfig yaml file:
- The sources are checked out.
- The application is published.
The image is assembled using a binary build.
See Section 6.3, “Deploying applications from binary artifacts using
oc” for additional information about binary builds.
Procedure
To configure the Jenkins master-slave pipeline:
Create the
buildconfig.yamlfile:kind: BuildConfig apiVersion: v1 metadata: name: dotnetapp-build spec: strategy: type: JenkinsPipeline jenkinsPipelineStrategy: jenkinsfile: |- node("dotnet-31") { stage('clone sources') { sh "git clone https://github.com/redhat-developer/s2i-dotnetcore-ex --branch dotnetcore-3.1 ." } stage('publish') { dir('app') { sh "dotnet publish -c Release" } } stage('create image') { dir('app') { sh 'oc new-build --name=dotnetapp dotnet:3.1 --binary=true || true' sh 'oc start-build dotnetapp --from-dir=bin/Release/{buildconfig-var}3.1/publish --follow' } } }Import the
BuildConfigfile to OpenShift:$ oc create -f buildconfig.yaml
- Open the OpenShift console.
Go to Builds → Pipelines.
The
dotnetapp-buildpipeline is available.Click Start Pipeline.
Mote that it may take a while for the build to start because the Jenkins image(s) need to be downloaded first.
During the build you can watch the different pipeline stages complete in the OpenShift console. You can also click View Log to see the pipeline stages complete in Jenkins.
When the Jenkins pipeline build is complete, go to Builds → Images.
The
dotnetappimage is built and available.
6.5. Environmental variables for .NET Core 3.1
The .NET Core images support several environment variables to control the build behavior of your .NET Core application. You can set these variables as part of the build configuration, or add them to the .s2i/environment file in the application source code repository.
| Variable Name | Description | Default |
|---|---|---|
| DOTNET_STARTUP_PROJECT |
Selects the project to run. This must be a project file (for example, |
|
| DOTNET_ASSEMBLY_NAME |
Selects the assembly to run. This must not include the |
The name of the |
| DOTNET_PUBLISH_READRYTORUN |
When set to |
|
| DOTNET_RESTORE_SOURCES |
Specifies the space-separated list of NuGet package sources used during the restore operation. This overrides all of the sources specified in the | |
| DOTNET_RESTORE_CONFIGFILE |
Specifies a | |
| DOTNET_TOOLS |
Specifies a list of .NET tools to install before building the app. It is possible to install a specific version by post pending the package name with | |
| DOTNET_NPM_TOOLS | Specifies a list of NPM packages to install before building the application. | |
| DOTNET_TEST_PROJECTS |
Specifies the list of test projects to test. This must be project files or folders containing a single project file. | |
| DOTNET_CONFIGURATION |
Runs the application in Debug or Release mode. This value should be either |
|
| DOTNET_VERBOSITY |
Specifies the verbosity of the | |
| HTTP_PROXY, HTTPS_PROXY | Configures the HTTP or HTTPS proxy used when building and running the application, respectively. | |
| DOTNET_RM_SRC |
When set to | |
| DOTNET_SSL_DIRS |
Specifies a list of folders or files with additional SSL certificates to trust. The certificates are trusted by each process that runs during the build and all processes that run in the image after the build (including the application that was built). The items can be absolute paths (starting with | |
| NPM_MIRROR | Uses a custom NPM registry mirror to download packages during the build process. | |
| ASPNETCORE_URLS |
This variable is set to | |
| DOTNET_RESTORE_DISABLE_PARALLEL |
When set to |
|
| DOTNET_INCREMENTAL |
When set to |
|
| DOTNET_PACK |
When set to |
6.6. Creating the MVC sample application
s2i-dotnetcore-ex is the default Model, View, Controller (MVC) template application for .NET Core.
This application is used as the example application by the .NET Core S2I image and can be created directly from the OpenShift UI using the Try Example link.
The application can also be created with the OpenShift client binary (oc).
Procedure
To create the sample application using oc:
Add the .NET Core application:
$ oc new-app dotnet:3.1~https://github.com/redhat-developer/s2i-dotnetcore-ex#dotnetcore-3.1 --context-dir=app
Make the application accessible externally:
$ oc expose service s2i-dotnetcore-ex
Obtain the sharable URL:
$ oc get route s2i-dotnetcore-ex
Additional resources
6.7. Creating the CRUD sample application
s2i-dotnetcore-persistent-ex is a simple Create, Read, Update, Delete (CRUD) .NET Core web application that stores data in a PostgreSQL database.
Procedure
To create the sample application using oc:
Add the database:
$ oc new-app postgresql-ephemeral
Add the .NET Core application:
$ oc new-app dotnet:3.1~https://github.com/redhat-developer/s2i-dotnetcore-persistent-ex#dotnetcore-3.1 --context-dir app
Add environment variables from the
postgresqlsecret and database service name environment variable:$ oc set env dc/s2i-dotnetcore-persistent-ex --from=secret/postgresql -e database-service=postgresql
Make the application accessible externally:
$ oc expose service s2i-dotnetcore-persistent-ex
Obtain the sharable URL:
$ oc get route s2i-dotnetcore-persistent-ex
Additional resources