Getting started with .NET on RHEL 8
Installing and running .NET 8.0 on RHEL 8
Abstract
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.
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Chapter 1. Introducing .NET 8.0
.NET is a general-purpose development platform featuring automatic memory management and modern programming languages. Using .NET, you can build high-quality applications efficiently. .NET is available on Red Hat Enterprise Linux (RHEL) and OpenShift Container Platform through certified containers.
.NET 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 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 8.0 is supported on RHEL 8.9 and later, RHEL 9.3 and later, and supported OpenShift Container Platform versions.
Chapter 2. Installing .NET 8.0
.NET 8.0 is included in the AppStream repositories for RHEL 8. The AppStream repositories are enabled by default on RHEL 8 systems.
You can install the .NET 8.0 runtime with the latest 8.0 Software Development Kit (SDK). When a newer SDK becomes available for .NET 8.0, you can install it by running sudo yum install
.
Prerequisites
Installed and registered RHEL 8.9 with attached subscriptions.
For more information, see Performing a standard RHEL 8 installation.
Procedure
Install .NET 8.0 and all of its dependencies:
$ sudo yum install dotnet-sdk-8.0 -y
Verification steps
Verify the installation:
$ dotnet --info
The output returns the relevant information about the .NET installation and the environment.
Chapter 3. Creating an application using .NET 8.0
Learn how to create a C# hello-world
application.
Procedure
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 specifiedmy-app
directory.
Verification steps
Run the project:
$ dotnet run --project my-app
The output returns:
Hello World!
Chapter 4. Publishing applications with .NET 8.0
.NET 8.0 applications can be published to use a shared system-wide version of .NET or to include .NET.
The following methods exist for publishing .NET 8.0 applications:
- Self-contained deployment (SCD) - The application includes .NET. This method uses a runtime built by Microsoft.
- Framework-dependent deployment (FDD) - The application uses a shared system-wide version of .NET.
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, built by Red Hat, that uses a set of native dependencies.
Prerequisites
Existing .NET application.
For more information about how to create a .NET application, see Creating an application using .NET.
4.1. Publishing .NET applications
The following procedure outlines how to publish a framework-dependent application.
Procedure
Publish the framework-dependent application:
$ dotnet publish my-app -f net8.0
Replace my-app with the name of the application you want to publish.
Optional: If the application is for RHEL only, trim out the dependencies needed for other platforms:
$ dotnet publish my-app -f net8.0 -r rhel.8-architecture --self-contained false
Replace architecture based on the platform you are using:
-
For Intel:
x64
-
For IBM Z and LinuxONE:
s390x
-
For 64-bit Arm:
arm64
-
For IBM Power:
ppc64le
-
For Intel:
Chapter 5. Running .NET 8.0 applications in containers
Use the ubi8/dotnet-80-runtime
image to run a .NET application inside a Linux container.
The following example uses podman.
Procedure
Create a new MVC project in a directory called
mvc_runtime_example
:$ dotnet new mvc --output mvc_runtime_example
Publish the project:
$ dotnet publish mvc_runtime_example -f net8.0 /p:PublishProfile=DefaultContainer /p:ContainerBaseImage=registry.access.redhat.com/ubi8/dotnet-80-runtime:latest
Run your image:
$ podman run --rm -p8080:8080 mvc_runtime_example
Verification steps
View the application running in the container:
$ xdg-open http://127.0.0.1:8080
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:
$ oc apply [-n namespace] -f https://raw.githubusercontent.com/redhat-developer/s2i-dotnetcore/main/dotnet_imagestreams.json
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:
$ oc new-project sample-project
Add the ASP.NET Core application:
$ 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
Track the progress of the build:
$ oc logs -f bc/example-app
View the deployed application once the build is finished:
$ oc logs -f dc/example-app
The application is now accessible within the project.
Optional: Make the project accessible externally:
$ oc expose svc/example-app
Obtain the shareable URL:
$ oc get routes
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:
$ oc new-build --name=my-web-app dotnet:8.0-ubi8 --binary=true
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/net8.0/publish
Create a new application:
$ oc new-app my-web-app
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, |
|
DOTNET_ASSEMBLY_NAME |
Selects the assembly to run. This must not include the |
The name of the |
DOTNET_PUBLISH_READYTORUN |
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 |
Deprecated: Use | |
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 | |
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.
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:
$ oc new-app dotnet:8.0-ubi8~https://github.com/redhat-developer/s2i-dotnetcore-ex#dotnet-8.0 --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 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 application:
$ oc new-app dotnet:8.0-ubi8~https://github.com/redhat-developer/s2i-dotnetcore-persistent-ex#dotnet-8.0 --context-dir app
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
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
Chapter 7. Migration from previous versions of .NET
7.1. Migration from previous versions of .NET
Microsoft provides instructions for migrating from most previous versions of .NET Core.
If you are using a version of .NET that is no longer supported or want to migrate to a newer .NET version to expand functionality, see the following articles:
- Migrate from ASP.NET Core 7.0 to 8.0
- Migrate from ASP.NET Core 6.0 to 7.0
- Migrate from ASP.NET Core 5.0 to 6.0
- Migrate from ASP.NET Core 3.1 to 5.0
- Migrate from ASP.NET Core 3.0 to 3.1
- Migrate from ASP.NET Core 2.2 to 3.0
- Migrate from ASP.NET Core 2.1 to 2.2
- Migrate from .NET Core 2.0 to 2.1
- Migrate from ASP.NET to ASP.NET Core
- Migrating .NET Core projects from project.json
- Migrate from project.json to .csproj format
If migrating from .NET Core 1.x to 2.0, see the first few related sections in Migrate from ASP.NET Core 1.x to 2.0. These sections provide guidance that is appropriate for a .NET Core 1.x to 2.0 migration path.
7.2. Porting from .NET Framework
Refer to the following Microsoft articles when migrating from .NET Framework:
- For general guidelines, see Porting to .NET Core from .NET Framework.
- For porting libraries, see Porting to .NET Core - Libraries.
- For migrating to ASP.NET Core, see Migrating to ASP.NET Core.
Several technologies and APIs present in the .NET Framework are not available in .NET Core and .NET. If your application or library requires these APIs, consider finding alternatives or continue using the .NET Framework. .NET Core and .NET do not support the following technologies and APIs:
- Desktop applications, for example, Windows Forms and Windows Presentation Foundation (WPF)
- Windows Communication Foundation (WCF) servers (WCF clients are supported)
- .NET remoting
Additionally, several .NET APIs can only be used in Microsoft Windows environments. The following list shows examples of these Windows-specific APIs:
-
Microsoft.Win32.Registry
-
System.AppDomains
-
System.Security.Principal.Windows
Several APIs that are not supported in the default version of .NET 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.