setup-atmos

Version updated for https://github.com/cloudposse/github-action-setup-atmos to version v2.0.2.

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  • This action is used across all versions by 31 repositories.

Go to the GitHub Marketplace to find the latest changes.

Release notes

This PR fixes the EXDEV (cross-device link not permitted) error that occurs when using this action in Docker-in-Docker (DinD) and other containerized environments.

Fixes #98

Problem

In DinD environments (like ARC runners), the GitHub Actions temp directory (/__w/_temp/) and the installation target directory exist on different Docker filesystem layers. When the action attempts to use io.mv() (which calls fs.renameSync()), it fails with:

Error: EXDEV: cross-device link not permitted, rename '/__w/_temp/88be01d7-...' -> '/__w/_actions/cloudposse/github-action-setup-atmos/atmos/atmos'

This is a fundamental limitation of the rename system call - it cannot move files across different filesystems or device boundaries.

Solution

This PR implements two fixes:

1. Replace io.mv() with copy+delete pattern

File: src/installer.ts:218-223

  • Before: await io.mv(downloadPath, toolPath) - fails across device boundaries
  • After: await io.cp(downloadPath, toolPath) + await io.rmRF(downloadPath) - works across all filesystems

This is the standard workaround for cross-device file operations and is used throughout the GitHub Actions ecosystem.

2. Add detection for pre-installed atmos

Files: src/installer.ts:45-75, src/installer.ts:243-268

Added checkExistingAtmosInstallation() function that:

  • Checks if atmos is already available in PATH
  • Retrieves the installed version
  • Uses the existing installation if it satisfies the requested version spec
  • Falls back to downloading if version doesn’t match or not found

This benefits users who:

  • Pre-install atmos in custom runner images
  • Use the action in environments with atmos already available
  • Want to reduce unnecessary downloads and installation time

Benefits

  • ✅ Works reliably in DinD environments (ARC runners, containerized CI/CD)
  • ✅ Reduces unnecessary downloads when atmos is pre-installed
  • ✅ Maintains full backward compatibility
  • ✅ Proper error handling with debug logging
  • ✅ No breaking changes to the action interface

Testing Recommendations

  1. DinD Environment: Test in ARC DinD mode runner
  2. Pre-installed atmos: Test with atmos already in PATH
  3. Version matching: Test with version specs (latest, specific versions, semver ranges)
  4. Fallback behavior: Test when existing version doesn’t satisfy requirement
  5. Standard runner: Verify it still works in standard GitHub-hosted runners

Technical Details

The io.mv() function from @actions/io uses the underlying ioUtil.rename() method, which relies on the OS-level rename syscall. This syscall has the limitation that it cannot move files across different filesystem mount points or devices.

In Docker-in-Docker:

  • Temp directory: /__w/_temp/ (on one overlay filesystem)
  • Installation directory: /__w/_actions/... (on a different overlay filesystem)
  • Result: EXDEV error when attempting rename

The copy+delete pattern avoids this limitation by performing two separate operations, each within their respective filesystems.

  • Fixes #98
  • Related discussion in cloudposse/github-action-atmos-terraform-plan about DinD compatibility

🤖 Automatic Updates

why

  • Replace build-harness with atmos for readme genration

References

  • DEV-3229 Migrate from build-harness to atmos

why

  • Replace build-harness with atmos for readme genration

References

  • DEV-3229 Migrate from build-harness to atmos