Red Hat Summit Red Hat SummitSupportConsoleDevelopersStart a trialContact

Getting Started Guide for RHEL 8

.NET 3.0

Red Hat Customer Content Services

Abstract

.NET Core is a general purpose development platform featuring automatic memory management and modern programming languages. It allows users to build high-quality applications efficiently. .NET Core is available in Red Hat Enterprise Linux and OpenShift Container Platform via 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 in Red Hat Enterprise Linux and OpenShift Container Platform.
  • The capacity to more easily develop new .NET Core workloads on Microsoft Windows. Customers can deploy and run on either Red Hat Enterprise Linux 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 3.0 is supported on Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, and OpenShift Container Platform versions 3.3 and later.

This Getting Started Guide for RHEL 8 describes how to install .NET Core 3.0 on Red Hat Enterprise Linux (RHEL). See Red Hat Enterprise Linux documentation for more information about RHEL 8.

1.1. Install .NET Core
Copy link

.NET Core 3.0 is included in the AppStream repositories for RHEL 8. The AppStream repositories are enabled by default on RHEL 8 systems.

  1. Install .NET Core 3.0 and all of its dependencies: 

    $ sudo yum install dotnet-sdk-3.0 -y
    Copy to Clipboard Toggle word wrap

  2. Run the following command to verify the installation: 

    $ dotnet --info
.NET Core SDK (reflecting any global.json):
 Version:   3.0.100
 Commit:    xxxxxxxxxx

Runtime Environment:
 OS Name:     rhel
 OS Version:  8
 OS Platform: Linux
 RID:         rhel.8-x64
 Base Path:   /usr/lib64/dotnet/sdk/3.0.100/

Host (useful for support):
  Version: 3.0.0
  Commit:  xxxxxxxxxx

.NET Core SDKs installed:
  3.0.100 [/usr/lib64/dotnet/sdk]

.... omitted
    Copy to Clipboard Toggle word wrap

1.2. Create an Application
Copy link

  1. Create a new Console application in a directory called hello-world: 

    $ dotnet new console -o hello-world
  The template "Console Application" was created successfully.

  Processing post-creation actions...
  Running 'dotnet restore' on hello-world/hello-world.csproj...
  Restore completed in 87.21 ms for /home/<USER>/hello-world/hello-world.csproj.

  Restore succeeded.
    Copy to Clipboard Toggle word wrap

  2. Run the project: 

    $ cd hello-world
$ dotnet run
Hello World!
    Copy to Clipboard Toggle word wrap

1.3. Publish Applications
Copy link

The .NET Core 3.0 applications can be published to use a shared system-wide version of .NET Core or to include .NET Core. These two deployment types are called framework-dependent deployment (FDD) and self-contained deployment (SCD), respectively.

For RHEL, we recommend publishing by FDD. This method ensures the application is using an up-to-date version of .NET Core, built by Red Hat, that includes a specific set of native dependencies. On the other hand, SCD uses a runtime built by Microsoft.

  1. Use the following command to publish a framework-dependent application. 

    $ dotnet publish -f netcoreapp3.0 -c Release
    Copy to Clipboard Toggle word wrap

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

    $ dotnet restore -r rhel.8-x64
$ dotnet publish -f netcoreapp3.0 -c Release -r rhel.8-x64 --self-contained false
    Copy to Clipboard Toggle word wrap

1.4. Run Applications on Linux Containers
Copy link

This section shows how to use the ubi8/dotnet-30-runtime image to run a precompiled application inside a Linux container.

  1. Create a new mvc project in a directory named mvc_runtime_example. 

    $ dotnet new mvc -o mvc_runtime_example
$ cd mvc_runtime_example
    Copy to Clipboard Toggle word wrap

  2. Publish the project. 

    $ dotnet publish -f netcoreapp3.0 -c Release
    Copy to Clipboard Toggle word wrap

  3. Create the Dockerfile. 

    $ cat > Dockerfile <<EOF
FROM registry.access.redhat.com/ubi8/dotnet-30-runtime

ADD bin/Release/netcoreapp3.0/publish/ .

CMD ["dotnet", "mvc_runtime_example.dll"]
EOF
    Copy to Clipboard Toggle word wrap

  4. Build your image. 

    $ podman build -t dotnet-30-runtime-example .
    Copy to Clipboard Toggle word wrap

  5. Run your image. 

    $ podman run -d -p8080:8080 dotnet-30-runtime-example
    Copy to Clipboard Toggle word wrap
  6. View the result in a browser: http://127.0.0.1:8080.

Report a bug

2.1. Installing Image Streams
Copy link

The .NET Core image streams definition can be defined globally in the openshift namespace or locally in your specific project.

  1. If you are a system administrator or otherwise have sufficient permissions, change to the openshift project. Using the openshift project allows you to globally update the image stream definitions. 

    $ oc project openshift
    Copy to Clipboard Toggle word wrap

    If you do not have permissions to use the openshift project, you can still update your project definitions starting with Step 2.

  2. Run the following commands to list all available .NET Core image versions. 

    $ oc describe is dotnet -n openshift
$ oc describe is dotnet
    Copy to Clipboard Toggle word wrap

    The output shows installed images or the message Error from server (NotFound) if no images are installed.

  3. Enter the following command to import new image streams. 

    $ oc create -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/dotnet_imagestreams_rhel8.json
    Copy to Clipboard Toggle word wrap

    If image streams were already installed, use the replace command to update the image stream definitions. 

    $ oc replace -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/dotnet_imagestreams_rhel8.json
    Copy to Clipboard Toggle word wrap

2.2. Deploying Applications from Source
Copy link

  1. Run the following commands to deploy the ASP.NET Core application, which is in the app folder on the dotnetcore-3.0 branch of the redhat-developer/s2i-dotnetcore-ex GitHub repository. 

    $ oc new-app --name=exampleapp 'dotnet:3.0~https://github.com/redhat-developer/s2i-dotnetcore-ex#dotnetcore-3.0' --build-env DOTNET_STARTUP_PROJECT=app
    Copy to Clipboard Toggle word wrap

  2. Use the oc logs command to track progress of the build. 

    $ oc logs -f bc/exampleapp
    Copy to Clipboard Toggle word wrap

  3. View the deployed application once the build is finished. 

    $ oc logs -f dc/exampleapp
    Copy to Clipboard Toggle word wrap

  4. 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
    Copy to Clipboard Toggle word wrap

2.3. Deploying Applications from Binary Artifacts
Copy link

The .NET Core S2I builder image can be used to build an application using binary artifacts that you provide.

  1. 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
    Copy to Clipboard Toggle word wrap

  2. Create a new binary build using the oc new-build command. 

    $ oc new-build --name=mywebapp dotnet:3.0 --binary=true
    Copy to Clipboard Toggle word wrap

  3. 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/netcoreapp3.0/publish
    Copy to Clipboard Toggle word wrap

  4. Create a new application using the oc new-app command. 

    $ oc new-app mywebapp
    Copy to Clipboard Toggle word wrap

2.4. Environment Variables
Copy link

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 NameDescriptionDefault

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.

 

DOTNET_STARTUP_ASSEMBLY

Used to specify the path of the entrypoint assembly within the source repository. When set, the source repository must contain a pre-built application.

 

2.5. Sample Applications
Copy link

Three sample applications are available:

  • dotnet-example: This is the default model–view–controller (MVC) application.
  • dotnet-runtime-example: This shows how to build an MVC application using a chained build. The application is built in ubi8/dotnet-30. The result is deployed in ubi8/dotnet-30-runtime. Note that chained builds are not supported on OpenShift Online.

  • dotnet-pgsql-persistent: This is the Microsoft ASP.NET Core MusicStore sample application using a PostgreSQL backend.

    Note

    This application uses .NET Core 2.1 LTS.

To add the samples using the OpenShift Web Console, browse to your project and click Add to project. You can filter for dotnet. If the samples do not show up, you can add them to your installation by running the following commands. 

$ oc create -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/templates/dotnet-example.json
$ oc create -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/templates/dotnet-runtime-example.json
$ oc create -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/master/templates/dotnet-pgsql-persistent.json
Copy to Clipboard Toggle word wrap

Report a bug

Chapter 3. Migrating to .NET Core 3.0
Copy link

This chapter provides migration information for .NET Core 3.0.

3.1. Migrating from previous versions of .NET Core
Copy link

See the following Microsoft articles to migrate from previous versions of .NET Core to newer versions of .NET Core.

Review the following information to migrate from the .NET Framework.

3.2.1. Migration Considerations
Copy link

Several technologies and APIs present in the .NET Framework are not available in .NET Core. If your application or library requires these APIs, consider finding alternatives or continue using the .NET Framework. .NET Core does not support the following technologies and APIs:

  • Windows Communication Foundation (WCF) servers (WCF clients are supported)
  • .NET remoting

Additionally, a number of .NET APIs can only be used in Microsoft Windows environments. The following list shows a few examples of these Windows-specific APIs:

  • Microsoft.Win32.Registry
  • System.AppDomains
  • System.Security.Principal.Windows

Consider using the .NET Portability Analyzer to identify API gaps and potential replacements. For example, enter the following command to find out how much of the API used by your .NET Framework 4.6 application is supported by .NET Core 2.1. 

$ dotnet /path/to/ApiPort.dll analyze -f . -r html --target '.NET Framework,Version=4.6' --target '.NET Core,Version=2.1'
Copy to Clipboard Toggle word wrap
Important

Several APIs that are not supported in the out-of-the-box version of .NET Core may be available from the Microsoft.Windows.Compatibility nuget package. Be careful when using this nuget package. Some of the APIs provided (such as Microsoft.Win32.Registry) only work on Windows, making your application incompatible with Red Hat Enterprise Linux.

3.2.2. .NET Framework Migration Articles
Copy link

Refer to the following Microsoft articles when migrating from .NET Framework.

Report a bug

Appendix A. Revision History
Copy link

Expand
DateVersionAuthorChanges

08/21/2017

2.0

Les Williams

Generally available

08/30/2017

2.0

Les Williams

Revised DOTNET_STARTUP_PROJECT and DOTNET_TEST_PROJECTS entries in Section 2.3

09/13/2017

2.0

Les Williams

Revised Section 1.2 to include a note about how to permanently enable rh-dotnet20

02/14/2018

2.0

Les Williams

Revised Section 2.2 to resolve BZ 1500230; added quoting for zsh and other shells

02/28/2018

2.0.3

Les Williams

Revised to include SDK 2.0 and 2.1

06/14/2018

2.1

Les Williams

Generally available

08/01/2018

2.1

Toby Drake

Added Chapter 3 to provide migration instructions

08/24/2018

2.1

Toby Drake

Added steps to enable a user to get new image streams

09/18/2018

2.1

Toby Drake

Revised Section 2.1 to include -n openshift in a command for listing .NET Core image versions. Modified the grep command to enable better search results.

10/12/2018

2.1

Toby Drake

Added DOTNET_SSL_DIRS and DOTNET_RM_SRC to Environment Variables. Added Deploy Applications from Binary Artifacts.

11/08/2018

2.1

Toby Drake

Changed references from docker to podman. Changed registry server to registry.redhat.io. Added procedure to set up Jenkins master-slave pipeline.

12/04/2018

2.2

Toby Drake

Generally available

12/06/2018

2.2

Les Williams

Added link for migrating from ASP.NET Core 2.1 to 2.2

04/16/2019

2.2

Les Williams

Revised environment variables section for DOTNET_INCREMENTAL and DOTNET_PACK variables

Report a bug

Legal Notice
Copy link

Copyright © 2020 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.
Back to top
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.

Theme

© 2025 Red Hat