HOME is overridden for containers

Describe the bug If passing the HOME environment variable to a container configuration, it will get ignored and set to /github/home anyway as per https://github.com/actions/runner/blob/4e85b8f3b7493aa1adf9dd0a574a9fa2bf1add71/src/Runner.Worker/ContainerOperationProvider.cs#L258

To Reproduce

A workflow with

jobs:
  main:
    runs-on: ubuntu-latest
    container:
      image: 'rokmoln/sf-ubuntu-bionic-common:0.2.80'
      options: '--user sf:sf' # this user's home is /home/sf
      env:
        HOME: /home/sf # tried to change HOME from /github/home to /home/sf. doesn't work
    steps:
      - shell: bash
        run: |
          echo $HOME

will echo /github/home instead of /home/sf.

Expected behavior Expected HOME to be left as is, as sf user’s HOME, or at the very least to be allowed to enforce it via the env dictionary.

Runner Version and Platform

2.274.2

What’s not working?

N/A

Job Log Output

N/A

Runner and Worker’s Diagnostic Logs

N/A

[andreineculau]

@Hoxu you touched on the most important bit:

On a related note, it would be really nice if the GitHub runner’s parameters to docker containers were documented clearly somewhere.

[andreineculau]

If I may suggest a possible solution:

• set HOME only if not already set
• set GITHUB_HOME or GITHUB_RUNNER_HOME in order to allow devs not to hardcode /github/home in case there’s a use-case to access the runner’s home from inside a container.