Chapter 1. Using .NET Core 3.0 on Red Hat Enterprise Linux

Install RHEL 7 using one of the following images:

Use the following command to register the system.

$ sudo subscription-manager register

You can also register the system by following the appropriate steps in Registering and Unregistering a System in the Red Hat Subscription Management document.

Display a list of all subscriptions that are available for your system and identify the pool ID for the subscription.

$ sudo subscription-manager list --available

This command displays the subscription name, unique identifier, expiration date, and other details related to it. The pool ID is listed on a line beginning with Pool ID.

Attach the subscription that provides access to the dotNET on RHEL repository. Use the pool ID you identified in the previous step.

$ sudo subscription-manager attach --pool=<appropriate pool ID from the subscription>

Enable the .NET Core channel for Red Hat Enterprise 7 Server, Red Hat Enterprise 7 Workstation, or HPC Compute Node with one of the following commands, respectively.

$ sudo subscription-manager repos --enable=rhel-7-server-dotnet-rpms
$ sudo subscription-manager repos --enable=rhel-7-workstation-dotnet-rpms
$ sudo subscription-manager repos --enable=rhel-7-hpc-node-dotnet-rpms

Verify the list of subscriptions attached to your system.

$ sudo subscription-manager list --consumed

Install the scl tool.

$ sudo yum install scl-utils

Install .NET Core 3.0 and all of its dependencies.

$ sudo yum install rh-dotnet30 -y

Enable the rh-dotnet30 Software Collection environment so you can run dotnet commands in the bash shell.

This procedure installs the .NET Core 3.0 runtime with the latest 3.0 SDK. When a newer SDK becomes available, it automatically installs as a package update.

$ scl enable rh-dotnet30 bash

This command does not persist; it creates a new shell, and the dotnet command is only available within that shell. If you log out, use another shell, or open up a new terminal, the dotnet command is no longer enabled.

Run the following command to verify the installation succeeded.

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

Runtime Environment:
 OS Name:     rhel
 OS Version:  7
 OS Platform: Linux
 RID:         rhel.7-x64
 Base Path:   /opt/rh/rh-dotnet30/root/usr/lib64/dotnet/sdk/3.0.100/

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

.NET Core SDKs installed:
  3.0.100 [/opt/rh/rh-dotnet30/root/usr/lib64/dotnet/sdk]

.... omitted

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.

Run the project.

$ cd hello-world
$ dotnet run
Hello World!

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

$ dotnet publish -f netcoreapp3.0 -c Release

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

$ dotnet restore -r rhel.7-x64
$ dotnet publish -f netcoreapp3.0 -c Release -r rhel.7-x64 --self-contained false

Enable the Software Collection and pass the application name to run the application on a RHEL system.

$ scl enable rh-dotnet30 -- dotnet <app>.dll

This command can be added to a script that is published with the application. Add the following script to your project and update the APP variable.

#!/bin/bash

APP=<app>
SCL=rh-dotnet30
DIR="$(dirname "$(readlink -f "$0")")"

scl enable $SCL -- "$DIR/$APP" "$@"

To include the script when publishing, add this ItemGroup to the csproj file.

<ItemGroup>
    <None Update="<scriptname>" Condition="'$(RuntimeIdentifier)' == 'rhel.7-x64' and '$(SelfContained)' == 'false'" CopyToPublishDirectory="PreserveNewest" />
</ItemGroup>

Create a new mvc project in a directory named mvc_runtime_example.

$ dotnet new mvc -o mvc_runtime_example
$ cd mvc_runtime_example

Publish the project.

$ dotnet publish -f netcoreapp3.0 -c Release

Create the Dockerfile.

$ cat > Dockerfile <<EOF
FROM registry.redhat.io/dotnet/dotnet-30-runtime-rhel7

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

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

Build your image.

$ podman build -t dotnet-30-runtime-example .

Run your image.

$ podman run -d -p8080:8080 dotnet-30-runtime-example