add devcontainer.json config for .net 6 -Codespaces

[seantleonard]

Why this change?

Enhance the PR review experience in GitHub Codespaces. Currently, review productivity is hindered because the default Codespaces container only has .NET 8. (While there is work to add .net 8 to dab, this fix enables .net6 (current) compat in codespaces).

Pros:

• Everything that is needed is pre-installed in container:
  • .NET 6 SDK -> allows you to "view definition" and other symbols with intellisense
  • C# Dev Kit VsCode extension -> view solution , run tests etc.
• No need to update this file when DAB is updated to build against .NET 8.

Cons:

• Slower to load CodeSpace because container needs to build (1-3 minutes), but once built, easy access for future PR iterations.

What is this change?

• Docs used:
  • https://docs.github.com/en/codespaces/setting-up-your-project-for-codespaces/adding-a-dev-container-configuration/setting-up-your-dotnet-project-for-codespaces
  • https://github.com/devcontainers/features/tree/main/src/dotnet
• Adds folder .devcontainer
• Adds file devcontainer.json which
  • Uses .net 8 sdk image for future compatibility with DAB changes in .NET 8 upgrade #2140 .
  • Installs .net 6 SDK, Runtime, and ASPNETCORE
  • Installs C#devKit Vscode extension

Actual experience

1. When loading codespaces you'll see this container setup after selecting which codespace to create or reuse.
   
2. Auto install required extensions to make intellisense work:
   
3. Solution explorer works
   
4. Working intellisense!
   

[seesharprun]

You can speed up the codespaces build by pre-building the devcontainer on the repository. This is a trick I often use with various https://github.com/azure-samples repos.

[seantleonard]

You can speed up the codespaces build by pre-building the devcontainer on the repository. This is a trick I often use with various https://github.com/azure-samples repos.

@seesharprun thank you for your suggestion! That seems like it will help tremendously. I'll take a look and make the appropriate modifications.

[seesharprun]

If you need to test the .NET tool locally, you will need to add the .NET tools directory to the PATH which is not automatically done in the SDK repos:

{
    ...,
    "remoteEnv": {
        "PATH": "${containerEnv:PATH}:/root/.dotnet/tools"
    }
}

[Aniruddh25]

LGTM, thank you for adding innovative ways of improving productivity!

[severussundar]

Please add to the PR description the docs referenced for this change

[severussundar]

Thanks for this addition, will definitely improve the code review experience! :)

[seantleonard]

azp run

[seantleonard]

/azp run