ci: allow jobs to install tools from pinned nixpkgs

[malt3]

Context

We often need additional tools in GitHub Actions Workflow jobs. This extension to the setup_bazel_nix action adds a new parameter nixTools which (if provided) will install a list of tools for the duration of the job and add their store paths to the GITHUB_PATH env.

Proposed change(s)

• ci: allow jobs to install tools from pinned nixpkgs

Additional info

• test run (prints cowsay and ponysay output)

Checklist

• Update docs
• Add labels (e.g., for changelog category)
• Is PR title adequate for changelog?
• Link to Milestone

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[malt3]

@miampf FYI. This enables you to install tools like zip by specifying:

nixTools: |
  zip

[msanft]

This would require us to add the tools in the top-level workflow where the setup_bazel_nix action is first called, right. This might add some duplication throughout multiple workflows that all call the same action that requires a specific tool. But I'm not sure yet how to circumvent that the best way.

[msanft]

Other than my above comment, changes LGTM

[malt3]

This would require us to add the tools in the top-level workflow where the setup_bazel_nix action is first called, right. This might add some duplication throughout multiple workflows that all call the same action that requires a specific tool. But I'm not sure yet how to circumvent that the best way.

Agreed. This is not ideal but probably a good enough approximation. Ideally, any bash scripts used in the CI would be built and run using nix directly and would explicitly list direct dependencies.
Let’s go with this solution until we have a better idea.