Chapter 2. Using .NET Core 3.1 on Red Hat OpenShift Container Platform

2.1. Installing Image Streams
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.NET Core image streams are installed using image stream definitions from s2i-dotnetcore with the OpenShift client oc. A script is available to facilitate removing/installing/updating the image streams.

.NET Core image streams can be defined in the global openshift namespace, or locally in a project namespace. To update the openshift namespace definitions, you need sufficient permissions.

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.

2.1.1. Install using oc
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If no pull secret is present in the namespace, you must add one by following the instructions in Red Hat Container Registry Authentication.
Run the following commands to list the available .NET Core image streams.
```
oc describe is dotnet [-n <namespace>]
```
```
$ oc describe is dotnet [-n <namespace>]
```
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The output shows installed images or the message Error from server (NotFound) if no images are installed.

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

$ oc replace -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/dotnet_imagestreams.json

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If no image streams for .NET Core are present, you can install them using:

oc create -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/dotnet_imagestreams.json

$ oc create -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/dotnet_imagestreams.json

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2.1.2. Install using script
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The script can be used to install/remove/update .NET Core image streams.

2.1.3. Linux/macOS
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Download the script from https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/install-imagestreams.sh
Login to the OpenShift cluster using the oc login command.

Install/update the imagestreams.

./install-imagestreams.sh --os rhel7 [--namespace <namespace>]  [--user <subscription_user> --password <subscription_password>]

./install-imagestreams.sh --os rhel7 [--namespace <namespace>]  [--user <subscription_user> --password <subscription_password>]

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The pull secret can be added by providing the --user and --password arguments. If a pull secret is already present, these arguments are ignored.

You can run ./install-imagestreams.sh --help for more information on using this script.

2.1.4. Windows
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Download the script from https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/install-imagestreams.ps1
Login to the OpenShift cluster using the oc login command.

Install/update the imagestreams.

./install-imagestreams.sh --OS rhel7 [--Namespace <namespace>]  [-User <subscription_user> -Password <subscription_password>]

./install-imagestreams.sh --OS rhel7 [--Namespace <namespace>]  [-User <subscription_user> -Password <subscription_password>]

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The PowerShell ExecutionPolicy may prohibit executing this script. To relax the policy, you can run Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass -Force.

The pull secret can be added by providing the -User and -Password arguments. If a pull secret is already present, these arguments are ignored.

You can run Get-Help .\install-imagestreams.ps1 for more information on using this script.

2.2. Deploying Applications from Source
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Run the following commands to deploy the ASP.NET Core application, which is in the app folder on the dotnetcore-3.1 branch of the redhat-developer/s2i-dotnetcore-ex GitHub repository.

oc new-app --name=exampleapp 'dotnet:3.1~https://github.com/redhat-developer/s2i-dotnetcore-ex#dotnetcore-3.1' --build-env DOTNET_STARTUP_PROJECT=app

$ oc new-app --name=exampleapp 'dotnet:3.1~https://github.com/redhat-developer/s2i-dotnetcore-ex#dotnetcore-3.1' --build-env DOTNET_STARTUP_PROJECT=app

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Use the oc logs command to track progress of the build.
```
oc logs -f bc/exampleapp
```
```
$ oc logs -f bc/exampleapp
```
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View the deployed application once the build is finished.
```
oc logs -f dc/exampleapp
```
```
$ oc logs -f dc/exampleapp
```
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At this point, the application is accessible within the project. To make it accessible externally, use the oc expose command. You can then use oc get routes to find the URL.
```
oc expose svc/exampleapp
oc get routes
```
```
$ oc expose svc/exampleapp
$ oc get routes
```
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2.3. Deploying Applications from Binary Artifacts
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The .NET Core S2I builder image can be used to build an application using binary artifacts that you provide.

Publish your application as described in Publish Applications. For example, the following commands create a new web application and publish it.
```
dotnet new web -o webapp
cd webapp
dotnet publish -c Release
```
```
$ dotnet new web -o webapp
$ cd webapp
$ dotnet publish -c Release
```
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Create a new binary build using the oc new-build command.
```
oc new-build --name=mywebapp dotnet:3.1 --binary=true
```
```
$ oc new-build --name=mywebapp dotnet:3.1 --binary=true
```
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Start a build using the oc start-build command, specifying the path to the binary artifacts on your local machine.
```
oc start-build mywebapp --from-dir=bin/Release/netcoreapp3.1/publish
```
```
$ oc start-build mywebapp --from-dir=bin/Release/netcoreapp3.1/publish
```
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Create a new application using the oc new-app command.
```
oc new-app mywebapp
```
```
$ oc new-app mywebapp
```
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2.4. Using a Jenkins Slave
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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.

Change to the project where Jenkins is (or will be) deployed.
```
oc project <projectname>
```
```
$ oc project <projectname>
```
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Create a dotnet-jenkins-slave.yaml file. The value used for the <serviceAccount> element is the account used by the Jenkins slave. If no value is specified, the default service 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>

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>

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Import the configuration into the project.
```
oc create -f dotnet-jenkins-slave.yaml
```
```
$ oc create -f dotnet-jenkins-slave.yaml
```
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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:

First, the sources are checked out.
Second, the application is published.
Third, the image is assembled using a binary build. See Deploying Applications from Binary Artifacts for additional information about binary builds.

Complete the steps below to configure the example Jenkins master-slave pipeline.

Create the buildconfig.yaml file.

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/netcoreapp3.1/publish --follow'
            }
          }
        }

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/netcoreapp3.1/publish --follow'
            }
          }
        }

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Import the BuildConfig file to OpenShift.
```
oc create -f buildconfig.yaml
```
```
$ oc create -f buildconfig.yaml
```
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Launch the OpenShift console. Go to Builds > Pipelines. The dotnetapp-build pipeline is available.
Click Start Pipeline. 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 completes, go to Builds > Images. The dotnetapp image is built and available.

2.5. Environment Variables
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The .NET Core images support a number of environment variables to control the build behavior of your .NET Core application. These variables can be set as part of the build configuration, or they can be added to an .s2i/environment file in the application source code repository.

Expand

Variable Name	Description	Default
DOTNET_STARTUP_PROJECT	Selects project to run. This must be a project file (for example, `csproj` or `fsproj`) or a folder containing a single project file.	`.`
DOTNET_ASSEMBLY_NAME	Selects the assembly to run. This must not include the .dll extension. Set this to the output assembly name specified in `csproj` (PropertyGroup/AssemblyName).	The name of the `csproj` file
DOTNET_PUBLISH_READRYTORUN	When set to `true`, the application will be compiled ahead-of-time. This reduces startup time by reducing the amount of work the JIT needs to do when the application is loading.	`false`
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 `NuGet.config` file. This variable cannot be combined with `DOTNET_RESTORE_CONFIGFILE`.
DOTNET_RESTORE_CONFIGFILE	Specifies a `NuGet.Config` file to be used for restore operations. This variable cannot be combined with `DOTNET_RESTORE_SOURCES`.
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 `@<version>`.
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 test` is invoked for each item.
DOTNET_CONFIGURATION	Runs the application in Debug or Release mode. This value should be either `Release` or `Debug`.	`Release`
DOTNET_VERBOSITY	Specifies the verbosity of the `dotnet build` commands. When set, the environment variables are printed at the start of the build. This variable can be set to one of the msbuild verbosity values (`q[uiet]`, `m[inimal]`, `n[ormal]`, `d[etailed]`, and `diag[nostic]`).
HTTP_PROXY, HTTPS_PROXY	Configures the HTTP/HTTPS proxy used when building and running the application.
DOTNET_RM_SRC	When set to `true`, the source code will not be included in the image.
DOTNET_SSL_DIRS	Used to specify a list of folders/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 `/`) or paths in the source repository (for example, certificates).
NPM_MIRROR	Uses a custom NPM registry mirror to download packages during the build process.
ASPNETCORE_URLS	This variable is set to `http://*:8080` to configure ASP.NET Core to use the port exposed by the image. Changing this is not recommended.	`http://*:8080`
DOTNET_RESTORE_DISABLE_PARALLEL	When set to true, disables restoring multiple projects in parallel. This reduces restore timeout errors when the build container is running with low CPU limits.	`false`
DOTNET_INCREMENTAL	When set to true, the NuGet packages will be kept so they can be re-used for an incremental build.	`false`
DOTNET_PACK	When set to true, creates a `tar.gz` file at `/opt/app-root/app.tar.gz` that contains the published application.

2.6. Sample Applications
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Two sample applications are available for use with the .NET Core s2i builder.

2.6.1. s2i-dotnetcore-ex
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s2i-dotnetcore-ex is the default .NET Core MVC template application.

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 oc as follows:

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 .NET Core application accessible externally and show the url
oc expose service s2i-dotnetcore-ex
oc get route s2i-dotnetcore-ex

# 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 .NET Core application accessible externally and show the url
$ oc expose service s2i-dotnetcore-ex
$ oc get route s2i-dotnetcore-ex

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For more information about this application, see https://github.com/redhat-developer/s2i-dotnetcore-ex/tree/dotnetcore-3.1.

2.6.2. s2i-dotnetcore-persistent-ex
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s2i-dotnetcore-persistent-ex is the a simple CRUD .NET Core web application that stores data in a PostgreSQL database.

The application can be created using the OpenShift client oc as follows:

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 envvars from the the postgresql secret, and database service name envvar.
oc set env dc/s2i-dotnetcore-persistent-ex --from=secret/postgresql -e database-service=postgresql
Make the .NET Core application accessible externally and show the url
oc expose service s2i-dotnetcore-persistent-ex
oc get route s2i-dotnetcore-persistent-ex

# 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 envvars from the the postgresql secret, and database service name envvar.
$ oc set env dc/s2i-dotnetcore-persistent-ex --from=secret/postgresql -e database-service=postgresql

# Make the .NET Core application accessible externally and show the url
$ oc expose service s2i-dotnetcore-persistent-ex
$ oc get route s2i-dotnetcore-persistent-ex

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For more information about this application, see https://github.com/redhat-developer/s2i-dotnetcore-persistent-ex/tree/dotnetcore-3.1.

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2.1. Installing Image Streams
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2.1.1. Install using oc
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2.1.2. Install using script
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2.1.3. Linux/macOS
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2.1.4. Windows
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2.2. Deploying Applications from Source
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2.3. Deploying Applications from Binary Artifacts
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2.4. Using a Jenkins Slave
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2.5. Environment Variables
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2.6. Sample Applications
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2.6.1. s2i-dotnetcore-ex
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2.6.2. s2i-dotnetcore-persistent-ex
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Chapter 2. Using .NET Core 3.1 on Red Hat OpenShift Container Platform

2.1. Installing Image StreamsCopy linkLink copied to clipboard!

2.1.1. Install using ocCopy linkLink copied to clipboard!

2.1.2. Install using scriptCopy linkLink copied to clipboard!

2.1.3. Linux/macOSCopy linkLink copied to clipboard!

2.1.4. WindowsCopy linkLink copied to clipboard!

2.2. Deploying Applications from SourceCopy linkLink copied to clipboard!

2.3. Deploying Applications from Binary ArtifactsCopy linkLink copied to clipboard!

2.4. Using a Jenkins SlaveCopy linkLink copied to clipboard!

2.5. Environment VariablesCopy linkLink copied to clipboard!

2.6. Sample ApplicationsCopy linkLink copied to clipboard!

2.6.1. s2i-dotnetcore-exCopy linkLink copied to clipboard!

2.6.2. s2i-dotnetcore-persistent-exCopy linkLink copied to clipboard!

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2.1. Installing Image Streams
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2.1.1. Install using oc
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2.1.2. Install using script
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2.1.3. Linux/macOS
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2.1.4. Windows
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2.2. Deploying Applications from Source
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2.3. Deploying Applications from Binary Artifacts
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2.4. Using a Jenkins Slave
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2.5. Environment Variables
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2.6. Sample Applications
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2.6.1. s2i-dotnetcore-ex
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2.6.2. s2i-dotnetcore-persistent-ex
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