Agent Skills: GitHub Actions Troubleshooting

GitHub Actions Troubleshooting

Overview

When a GitHub Actions pipeline fails, systematically identify the problem, locate the failing step, and fix it. This skill helps interpret error output and determine the right fix.

When to Use This Skill

• User reports a failing GitHub Actions workflow
• User provides error output from CI
• User mentions a specific failing step (e.g., "Stack Unit Tests failed")
• Need to fix pipeline configuration issues

Troubleshooting Workflow

Step 1: Parse the Error Output

Look for key information in the error:

• Which workflow file: Often shown in logs or URL
• Step name: e.g., "Stack Unit Tests", "Run unit tests"
• Line number: e.g., "line 232 of deploy-stacks-main.yml"
• Error message: The actual failure (test failure, command not found, etc.)

Example error:

Run npm run test -- --coverage

> oncall-data-sync-stack@1.0.0 test
> jest --coverage

No tests found, exiting with code 1

Parse this as:

• Command: npm run test -- --coverage
• Problem: No tests found, jest exiting with code 1
• Likely fix needed: Add --passWithNoTests flag

Step 2: Locate the Failing Step

Read the workflow file at the specified line:

# If user mentions line 232 of deploy-stacks-main.yml

Look for:

• The name: of the step
• The run: command being executed
• Any working-directory: specified
• Conditional if: statements

Example:

- name: Stack Unit Tests
  working-directory: ./stacks/${{ matrix.stack_env.stack }}
  run: npm run test -- --coverage

Step 3: Identify the Root Cause

Common failure patterns:

Tests not found:

• Symptom: "No tests found, exiting with code 1"
• Cause: Test files deleted or no tests exist
• Fix: Add --passWithNoTests flag to jest command

Module not found:

• Symptom: "Cannot find module './some-file'"
• Cause: File deleted but still imported
• Fix: Remove import or restore file

Command not found:

• Symptom: "command not found: some-command"
• Cause: Missing dependency or wrong command name
• Fix: Install dependency or correct command

Wrong working directory:

• Symptom: "package.json not found" or similar
• Cause: Command run in wrong directory
• Fix: Update working-directory in workflow

Step 4: Determine Where to Fix

Fix in workflow file when:

• Issue is with how the step runs (flags, directory, conditions)
• Need to add/remove pipeline-specific configuration
• Example: Adding --passWithNoTests to workflow run command

Fix in package.json when:

• Issue affects both local and CI execution
• Test script needs permanent modification
• Want consistent behavior everywhere
• Example: Changing test script to include --passWithNoTests by default

Fix in source code when:

• Actual code/test failure
• Import errors, type errors, etc.
• Test assertions failing

Step 5: Apply the Fix

Update the appropriate file(s) and verify:

Workflow file fix:

# Before
run: npm run test -- --coverage

# After
run: npm run test -- --coverage --passWithNoTests

Package.json fix:

{
  "scripts": {
    "test": "jest --passWithNoTests"
  }
}

Common Issues and Fixes

Empty Test Suite

Error: "No tests found, exiting with code 1" Fix: Add --passWithNoTests to jest command (workflow or package.json)

Multiple Workflow Files

Error: Unclear which workflow is failing Fix: Check error output for workflow name, or look at GitHub Actions UI for which workflow ran

Matrix Strategy Failures

Error: Only one matrix item failing Fix: cd to that specific directory and run the command locally to debug

Cached Dependencies

Error: "Module not found" but package.json has it Fix: May be cache issue - workflow often has cache step, check cache key

Example Troubleshooting Session

User reports:

"Stack Unit Tests failing with 'No tests found' error"

Actions:

1. Ask for error output or workflow file name
2. User provides: "Line 232 of deploy-stacks-main.yml"
3. Read that file at line 232:

   - name: Stack Unit Tests
     run: npm run test -- --coverage
   

4. Identify issue: jest with no tests exits with code 1
5. Determine fix location: Both package.json (permanent) and workflow (explicit)
6. Apply fix:
   • Update package.json: "test": "jest --passWithNoTests"
   • Update workflow: run: npm run test -- --coverage --passWithNoTests
7. Verify fix will work

Best Practices

• Read the actual workflow file - Don't guess, verify what's running
• Check working directory - Commands run in specific contexts
• Consider both locations - Sometimes fix in package.json is cleaner
• Test locally first - Run the same command locally to verify fix
• Update related workflows - If multiple workflows run same command