Chapter 6. Using .NET 8.0 on OpenShift Container Platform 6.1. Overview NET images are added to OpenShift by importing imagestream definitions from s2i-dotnetcore . The imagestream definitions include the dotnet imagestream which contains sdk images for different supported versions of .NET. Life Cycle and Support Policies for the .NET Program provides an up-to-date overview of supported versions. Version Tag Alias .NET 6.0 dotnet:6.0-ubi8 dotnet:6.0 .NET 7.0 dotnet:7.0-ubi8 dotnet:7.0 .NET 8.0 dotnet:8.0-ubi8 dotnet:8.0 The sdk images have corresponding runtime images which are defined under the dotnet-runtime imagestream. The container images work across different versions of Red Hat Enterprise Linux and OpenShift. The UBI-8 based images (suffix -ubi8) are hosted on the registry.access.redhat.com and do not require authentication. 6.2. Installing .NET image streams To install .NET 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. You can define .NET image streams in the global openshift namespace or locally in a project namespace. Sufficient permissions are required to update the openshift namespace definitions. Procedure Install (or update) the image streams: 6.3. 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 dotnet-8.0 branch of the redhat-developer/s2i-dotnetcore-ex GitHub repository: Procedure Create a new OpenShift project: Add the ASP.NET Core application: Track the progress of the build: View the deployed application once the build is finished: The application is now accessible within the project. Optional : Make the project accessible externally: Obtain the shareable URL: 6.4. Deploying applications from binary artifacts using oc You can use .NET 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: Start the build and specify the path to the binary artifacts on your local machine: Create a new application: 6.5. Environment variables for .NET 8.0 The .NET images support several environment variables to control the build behavior of your .NET 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, 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_READYTORUN 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 perform 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 or HTTPS proxy used when building and running the application, respectively. DOTNET_RM_SRC When set to true , the source code will not be included in the image. DOTNET_SSL_DIRS Deprecated : Use SSL_CERT_DIR instead SSL_CERT_DIR 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 / ) 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. 6.6. Creating the MVC sample application s2i-dotnetcore-ex is the default Model, View, Controller (MVC) template application for .NET. This application is used as the example application by the .NET 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 application: Make the application accessible externally: Obtain the sharable URL: Additional resources s2i-dotnetcore-ex application repository on GitHub 6.7. Creating the CRUD sample application s2i-dotnetcore-persistent-ex is a simple Create, Read, Update, Delete (CRUD) .NET web application that stores data in a PostgreSQL database. Procedure To create the sample application using oc : Add the database: Add the .NET application: Add environment variables from the postgresql secret and database service name environment variable: Make the application accessible externally: Obtain the sharable URL: Additional resources s2i-dotnetcore-ex application repository on GitHub

Commands:
oc apply [-n namespace ] -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/main/dotnet_imagestreams.json
oc new-project sample-project
oc new-app --name= example-app 'dotnet:8.0-ubi8~https://github.com/redhat-developer/s2i-dotnetcore-ex#dotnet-8.0' --build-env DOTNET_STARTUP_PROJECT=app
oc logs -f bc/ example-app
oc logs -f dc/ example-app
oc expose svc/ example-app
oc get routes
oc new-build --name= my-web-app dotnet:8.0-ubi8 --binary=true
oc start-build my-web-app --from-dir= bin/Release/net8.0/publish
oc new-app my-web-app
oc new-app dotnet:8.0-ubi8~https://github.com/redhat-developer/s2i-dotnetcore-ex#dotnet-8.0 --context-dir=app
oc expose service s2i-dotnetcore-ex
oc get route s2i-dotnetcore-ex
oc new-app postgresql-ephemeral
oc new-app dotnet:8.0-ubi8~https://github.com/redhat-developer/s2i-dotnetcore-persistent-ex#dotnet-8.0 --context-dir app
oc set env dc/s2i-dotnetcore-persistent-ex --from=secret/postgresql -e database-service=postgresql
oc expose service s2i-dotnetcore-persistent-ex
oc get route s2i-dotnetcore-persistent-ex