feat: Allow the shell to be configured for workflow command steps

[anryko]

what

Added an option to define the shell for the custom workflow steps with the command filed, like run, env, and multienv.

why

• This change simplifies writing more elaborate shell logic.
• The same functionality is achievable by running command: bash -c "my inline shell script", but dealing with double quote escaping within the shell script is quite cumbersome.
• The default busybox shell is limited and having "native" access to bash will improve user experience.

tests

• I run the unit tests.
• I verified manually tested this functionality on a local setup.
• log example:

  {"level":"debug","ts":"2024-11-03T20:45:25.618Z","caller":"models/shell_command_runner.go:114","msg":"starting 'sh -c \"echo 002\"' in '/home/atlantis/.atlantis/repos/test/infra-test/355/default/terraform/gcp/gcp-demo-1111/random'","json":{"repo":"test/infra-test","pull":"355"}}
  {"level":"info","ts":"2024-11-03T20:45:25.626Z","caller":"models/shell_command_runner.go:181","msg":"successfully ran 'sh -c \"echo 002\"' in '/home/atlantis/.atlantis/repos/test/infra-test/355/default/terraform/gcp/gcp-demo-1111/random'","json":{"repo":"test/infra-test","pull":"355","duration":0.009693026}}
  {"level":"debug","ts":"2024-11-03T20:45:25.630Z","caller":"models/shell_command_runner.go:114","msg":"starting 'bash -c \"echo ${DIR%$REPO_REL_DIR}\"' in '/home/atlantis/.atlantis/repos/test/infra-test/355/default/terraform/gcp/gcp-demo-1111/random'","json":{"repo":"test/infra-test","pull":"355"}}
  {"level":"info","ts":"2024-11-03T20:45:25.662Z","caller":"models/shell_command_runner.go:181","msg":"successfully ran 'bash -c \"echo ${DIR%$REPO_REL_DIR}\"' in '/home/atlantis/.atlantis/repos/test/infra-test/355/default/terraform/gcp/gcp-demo-1111/random'","json":{"repo":"test/infra-test","pull":"355","duration":0.032133774}}
  

references

• Closes: Allow Specifying Custom Script Runner #1417

[X-Guardian]

Hi @anryko, thanks for this. Any chance you can follow the same pattern as the pre/post workflow hooks to have the ability to specify the shell and shellargs. See https://www.runatlantis.io/docs/pre-workflow-hooks.html#reference.

I also see no reason to limit the shell to bash and sh.

[anryko]

@X-Guardian sure, I'll do that. I would suggest to make shellArgs to be a list. This would make sense because it's a list of arguments and will be consistent with extra_args property (like plan.extra_args []string).

[anryko]

@X-Guardian I added support for shellArgs and removed the limit for the shell option as it was suggested.

[X-Guardian]

Nearly there @anryko. Once you have added the debug log lines, can you add some log snippets to the PR description as evidence that this functionality is working.

[X-Guardian]

Thanks for your work on this @anryko. You can test it by using one of the following container images: dev-debian-8285a0f or dev-alpine-8285a0f