Unpacking GitHub Actions: Unexpected Bash Exit Codes and Workflow Reliability

In the intricate world of continuous integration and deployment (CI/CD), precise error handling and predictable tool behavior are paramount. Developers rely heavily on exit codes to determine the success or failure of commands, driving subsequent workflow steps. However, a recent GitHub Community discussion highlights a puzzling issue where Bash exit codes in GitHub Actions workflows are not behaving as expected, raising questions about workflow reliability and the efficacy of certain software engineering management tools.

The Case of the Disappearing Exit Code

The discussion, initiated by user amaschas, details an unintuitive interaction within a GitHub Actions runner. The core problem revolves around capturing the exit code of a tofu plan command. When executed outside the GitHub Actions environment, tofu plan -no-color -detailed-exitcode correctly returns an exit code of 2 (indicating changes are pending). However, within the action runner, the PLAN_EXIT_CODE variable consistently gets set to 0, suggesting a successful execution despite the underlying command's actual status.

Here's the problematic code snippet shared by amaschas:

- name: OpenTofu Plan
  shell: bash {0}
  run: |
    tofu plan -no-color -detailed-exitcode
    PLAN_EXIT_CODE=$?
    echo "Plan exit code: $PLAN_EXIT_CODE"
  continue-on-error: true

Initial Suspicions and Persistent Behavior

Amaschas initially suspected that the issue might stem from an interaction with continue-on-error: true or the specific shell: bash {0} configuration. The expectation was that Bash exit codes should remain unaltered, regardless of workflow settings designed to control step failure. The automated response from github-actions acknowledged the feedback but offered no immediate solution or workaround, directing users to changelogs and roadmaps instead.

In a follow-up, amaschas confirmed trying several variations, including:

• Omitting continue-on-error entirely.
• Adding explicit set +e to prevent immediate exit on error.

Despite these attempts, the incorrect exit code of 0 persisted, leading to the strong suspicion that this might be an actual bug within the GitHub Actions runner environment or its Bash shell interpretation.

Implications for Developer Productivity and Management

This kind of behavior has significant implications for developer productivity and the reliability of automated workflows. When critical commands like tofu plan (or similar tools that use detailed exit codes for status reporting) fail to accurately communicate their state, it can lead to:

• False Positives: Workflows might proceed as if successful, even when infrastructure changes are pending or errors have occurred, potentially deploying unverified code or configurations.
• Debugging Headaches: Developers spend valuable time investigating why their scripts behave differently in CI/CD than locally, slowing down development cycles.
• Erosion of Trust: Unpredictable tool behavior undermines confidence in the automation platform itself, making it harder to rely on for critical operations.

For teams leveraging software engineering management tools like GitHub Actions to track development kpi examples such as successful build rates or deployment frequencies, such discrepancies can skew metrics and provide an inaccurate picture of project health. Accurate exit code capture is fundamental for robust error handling, conditional logic in workflows, and ultimately, for maintaining a reliable deployment pipeline.

Seeking Clarity and Robust Solutions

While the discussion did not yield a definitive solution or official workaround, it underscores the need for clear documentation on how GitHub Actions handles shell execution and exit codes, especially in edge cases involving error handling directives. Developers often need to implement more robust checks, such as parsing command output directly, when direct exit code capture proves unreliable.

This community insight highlights a crucial area where the predictability of underlying shell behavior within CI/CD environments is vital. As developers continue to push the boundaries of automation, ensuring that fundamental mechanisms like exit codes work as expected is essential for maintaining efficient, trustworthy, and productive development workflows.