Red Hat Summit Red Hat SummitSupportConsoleDevelopersStart a trialContact

Getting started with .NET on RHEL 9

.NET 3.1

Installing and running .NET Core 3.1 on RHEL 9

Red Hat Customer Content Services

Abstract

This guide describes how to install and run .NET Core 3.1 on RHEL 9. Note that .NET Core 3.1 is only available in RHEL 9 Beta. .NET Core 3.1 will be replaced with .NET 6.0 in RHEL 9 GA.

Preface

Important

.NET Core 3.1 is only provided in RHEL 9 Beta. .NET Core 3.1 will be removed and replaced with .NET 6.0 in RHEL 9 GA.

Making open source more inclusive

Red Hat is committed to replacing problematic language in our code, documentation, and web properties. We are beginning with these four terms: master, slave, blacklist, and whitelist. Because of the enormity of this endeavor, these changes will be implemented gradually over several upcoming releases. For more details, see our CTO Chris Wright’s message.

Providing feedback on Red Hat documentation

We appreciate your input on our documentation. Please let us know how we could make it better. To do so:

  • For simple comments on specific passages:

    1. Make sure you are viewing the documentation in the Multi-page HTML format. In addition, ensure you see the Feedback button in the upper right corner of the document.
    2. Use your mouse cursor to highlight the part of text that you want to comment on.
    3. Click the Add Feedback pop-up that appears below the highlighted text.
    4. Follow the displayed instructions.

  • For submitting more complex feedback, create a Bugzilla ticket:

    1. Go to the Bugzilla website.
    2. As the Component, use Documentation.
    3. Fill in the Description field with your suggestion for improvement. Include a link to the relevant part(s) of documentation.
    4. Click Submit Bug.

Chapter 1. Introducing .NET Core 3.1

.NET Core is a general-purpose development platform featuring automatic memory management and modern programming languages. Using .NET, you can build high-quality applications efficiently. .NET Core is available on Red Hat Enterprise Linux (RHEL) and OpenShift Container Platform through certified containers.

.NET Core offers the following features:

  • The ability to follow a microservices-based approach, where some components are built with .NET and others with Java, but all can run on a common, supported platform on RHEL and OpenShift Container Platform.
  • The capacity to more easily develop new .NET Core workloads on Microsoft Windows. You can deploy and run your applications on either RHEL or Windows Server.
  • A heterogeneous data center, where the underlying infrastructure is capable of running .NET applications without having to rely solely on Windows Server.

.NET Core 3.1 is supported on RHEL 7, RHEL 8, RHEL 9, and OpenShift Container Platform versions 3.3 and later.

Chapter 2. Installing .NET Core 3.1

.NET Core 3.1 is included in the AppStream repositories for RHEL 9. The AppStream repositories are enabled by default on RHEL 9 systems.

You can install the .NET Core 3.1 runtime with the latest 3.1 Software Development Kit (SDK). When a newer SDK becomes available for .NET Core 3.1, you can install it by running sudo yum install.

Prerequisites

Procedure

  • Install .NET Core 3.1 and all of its dependencies: 

    $ sudo yum install dotnet-sdk-3.1 -y

Verification steps

  • Verify the installation: 

    $ dotnet --info

    The output returns the relevant information about the .NET Core installation and the environment.

Chapter 3. Creating an application using .NET Core 3.1

Learn how to create a C# hello-world application.

Procedure

  1. Create a new Console application in a directory called my-app: 

    $ dotnet new console --output my-app

    The output returns: 

    The template "Console Application" was created successfully.

Processing post-creation actions...
Running 'dotnet restore' on my-app/my-app.csproj...
  Determining projects to restore...
  Restored /home/username/my-app/my-app.csproj (in 67 ms).
Restore succeeded.

    A simple Hello World console application is created from a template. The application is stored in the specified my-app directory.

Verification steps

  • Run the project: 

    $ dotnet run --project my-app

    The output returns: 

    Hello World!

Chapter 4. Publishing applications with .NET Core 3.1

.NET Core 3.1 applications can be published to use a shared system-wide version of .NET Core or to include .NET Core.

The following methods exist for publishing .NET Core 3.1 applications:

  • Framework-dependent deployment (FDD) - The application uses a shared system-wide version of .NET.
Note

When publishing an application for RHEL, Red Hat recommends using FDD, because it ensures that the application is using an up-to-date version of .NET Core, built by Red Hat, that uses a set of native dependencies.

  • Self-contained deployment (SCD) - The application includes .NET. This method uses a runtime built by Microsoft.

Prerequisites

  • Existing .NET Core application.

    For more information on how to create a .NET Core application, see

4.1. Publishing .NET Core applications

The following procedure outlines how to publish a framework-dependent application.

Procedure

  1. Publish the framework-dependent application: 

    $ dotnet publish my-app -f netcoreapp3.1 -c Release

    Replace my-app with the name of the application you want to publish.

  2. Optional: If the application is for RHEL only, trim out the dependencies needed for other platforms: 

    $ dotnet restore my-app -r rhel.9-x64
$ dotnet publish my-app -f netcoreapp3.1 -c Release -r rhel.9-x64 --self-contained false
    Note

    If you are using an arm64/aarch64 machine, use: 

    $ dotnet restore my-app -r rhel.9-arm64
$ dotnet publish my-app -f netcoreapp3.1 -c Release -r rhel.9-arm64 --self-contained false

Chapter 5. Running .NET Core 3.1 applications in containers

Use the ubi8/dotnet-31-runtime image to run a precompiled application inside a Linux container.

Prerequisites

  • Preconfigured containers.

    The following example uses podman.

Procedure

  1. Optional: If you are in another project’s directory and do not wish to create a nested project, return to the parent directory of the project: 

    $ cd ..

  2. Create a new MVC project in a directory called mvc_runtime_example: 

    $ dotnet new mvc --output mvc_runtime_example

  3. Publish the project: 

    $ dotnet publish mvc_runtime_example -f netcoreapp3.1 -c Release

  4. Create the Dockerfile: 

    $ cat > Dockerfile <<EOF
FROM registry.access.redhat.com/ubi8/dotnet-31-runtime

ADD bin/Release/netcoreapp3.1/publish/ .

CMD ["dotnet", "mvc_runtime_example.dll"]
EOF

  5. Build your image: 

    $ podman build -t dotnet-31-runtime-example .

  6. Run your image: 

    $ podman run -d -p8080:8080 dotnet-31-runtime-example

Verification steps

  • View the application running in the container: 

    $ xdg-open http://127.0.0.1:8080

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.

6.1.1. Installing image streams using OpenShift Client

You can use OpenShift Client (oc) to install .NET Core image streams.

Prerequisites

Procedure

  1. 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.

  2. Install the .NET Core image streams: 

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

  3. Include newer versions of existing .NET Core image streams: 

    $ 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

  1. Download the script.

    1. On Linux use: 

      $ wget https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/install-imagestreams.sh

    2. On Mac use: 

      $ curl https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/install-imagestreams.sh -o install-imagestreams.sh

  2. Make the script executable: 

    $ chmod +x install-imagestreams.sh

  3. Log in to the OpenShift cluster: 

    $ oc login

  4. Install image streams and add a pull secret for authentication against the registry.redhat.io: 

    ./install-imagestreams.sh --os rhel [--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 --user and --password arguments 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

  1. Download the script. 

    Invoke-WebRequest https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/install-imagestreams.ps1 -UseBasicParsing -OutFile install-imagestreams.ps1

  2. Log in to the OpenShift cluster: 

    $ oc login

  3. Install image streams and add a pull secret for authentication against the registry.redhat.io: 

    ./install-imagestreams.sh --OS rhel [-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 -User and -Password arguments are ignored.

Note

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

  1. Create a new OpenShift project: 

    $ oc new-project sample-project

  2. Add 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=app

  3. Track the progress of the build: 

    $ oc logs -f bc/example-app

  4. View the deployed application once the build is finished: 

    $ oc logs -f dc/example-app

    The application is now accessible within the project.

  5. Optional: Make the project accessible externally: 

    $ oc expose svc/example-app

  6. Obtain 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

  1. Published application.

    For more information, see

Procedure

  1. Create a new binary build: 

    $ oc new-build --name=my-web-app dotnet:3.1 --binary=true

  2. Start 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

  3. Create a new application: 

    $ oc new-app my-web-app

6.4. 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 NameDescriptionDefault

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_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 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

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.

 

6.5. 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:

  1. 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

  2. Make the application accessible externally: 

    $ oc expose service s2i-dotnetcore-ex

  3. Obtain the sharable URL: 

    $ oc get route s2i-dotnetcore-ex

Additional resources

6.6. 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:

  1. Add the database: 

    $ oc new-app postgresql-ephemeral

  2. 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

  3. Add environment variables from the postgresql secret and database service name environment variable: 

    $ oc set env dc/s2i-dotnetcore-persistent-ex --from=secret/postgresql -e database-service=postgresql

  4. Make the application accessible externally: 

    $ oc expose service s2i-dotnetcore-persistent-ex

  5. Obtain the sharable URL: 

    $ oc get route s2i-dotnetcore-persistent-ex

Additional resources

Legal Notice

Copyright © 2022 Red Hat, Inc.
The text of and illustrations in this document are licensed by Red Hat under a Creative Commons Attribution–Share Alike 3.0 Unported license ("CC-BY-SA"). An explanation of CC-BY-SA is available at http://creativecommons.org/licenses/by-sa/3.0/. In accordance with CC-BY-SA, if you distribute this document or an adaptation of it, you must provide the URL for the original version.
Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law.
Red Hat, Red Hat Enterprise Linux, the Shadowman logo, the Red Hat logo, JBoss, OpenShift, Fedora, the Infinity logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other countries.
Linux® is the registered trademark of Linus Torvalds in the United States and other countries.
Java® is a registered trademark of Oracle and/or its affiliates.
XFS® is a trademark of Silicon Graphics International Corp. or its subsidiaries in the United States and/or other countries.
MySQL® is a registered trademark of MySQL AB in the United States, the European Union and other countries.
Node.js® is an official trademark of Joyent. Red Hat is not formally related to or endorsed by the official Joyent Node.js open source or commercial project.
The OpenStack® Word Mark and OpenStack logo are either registered trademarks/service marks or trademarks/service marks of the OpenStack Foundation, in the United States and other countries and are used with the OpenStack Foundation's permission. We are not affiliated with, endorsed or sponsored by the OpenStack Foundation, or the OpenStack community.
All other trademarks are the property of their respective owners.
Red Hat logoGithubRedditYoutubeTwitter

Learn

Try, buy, & sell

Communities

About Red Hat Documentation

We help Red Hat users innovate and achieve their goals with our products and services with content they can trust. Explore our recent updates.

Making open source more inclusive

Red Hat is committed to replacing problematic language in our code, documentation, and web properties. For more details, see the Red Hat Blog.

About Red Hat

We deliver hardened solutions that make it easier for enterprises to work across platforms and environments, from the core datacenter to the network edge.

© 2024 Red Hat, Inc.