Solving Environment Variable Expansion Issues in GitHub Actions Workflows

Discover why your environment variables in GitHub Actions aren't expanding correctly and learn effective solutions for fixing them!
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Environment variables not always being expanded in GitHub Actions workflow file

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding Environment Variables in GitHub Actions Workflows

When automating your workflow on GitHub Actions, you may encounter an issue where environment variables do not expand correctly at specific stages of your configuration. This can lead to frustrating errors and interruptions in your deployment process. In this article, we’ll delve into why this happens and how you can easily rectify it.

The Problem: Environment Variables Not Expanding

Imagine you have a workflow that uses an environment variable to define a resource group name for deploying your Azure resources. You’ve set up your workflow as follows:

[[See Video to Reveal this Text or Code Snippet]]

This line should derive the resource group name based on the branch name used for triggering the workflow. However, upon reaching the final step of deployment, you encounter an error like:

[[See Video to Reveal this Text or Code Snippet]]

This indicates that the environment variable is not expanding to include the branch name as expected. Instead, it outputs a literal string, causing the subsequent command to fail due to an inability to locate the resource group.

Why This Happens: Understanding Shell Parameter Expansion

The unexpected behavior you’re experiencing can be attributed to how shell parameter expansion operates within YAML files. Specifically:

Shell parameter expansion does not occur automatically when assigning values in YAML.

The value of your environment variable is literally treated as rg-blue-${GITHUB_REF-refs/heads/}.

While the variable appears to work in earlier stages of the workflow, it actually gets expanded by the shell during execution—leading to confusion.

Example of Misleading Output

If you ran:

[[See Video to Reveal this Text or Code Snippet]]

It may appear to output rg-blue-my-branch-name, but the truth is the way the shell interprets it leads to different results when not properly configured.

Solutions: Fixing the Expansion Issue

To address the variable expansion issue, consider one of the following approaches:

1. Use a Separate Step to Set the Environment Variable

Instead of initially defining the environment variable in the env section, you can create a step that sets it appropriately within the workflow like this:

[[See Video to Reveal this Text or Code Snippet]]

This approach ensures that the environment variable is correctly populated before its final deployment usage.

[[See Video to Reveal this Text or Code Snippet]]

This method is more straightforward and eliminates the need for complex shell parameter expansion, ensuring your environment variable contains the expected branch name.

Conclusion: Making the Most of GitHub Actions

In summary, the issues with environment variable expansions in GitHub Actions workflows can complicate your CI/CD process. By understanding how variable expansion works and applying one of the proposed solutions, you can ensure that your deployments run smoothly and as expected. Embrace the power of automation with GitHub Actions and optimize your workflows effectively!