Examining environment variables in GitHub CI workflows

Examining environment variables in GitHub CI workflows

Environment variables in GitHub Actions provide a way to store and access sensitive information, configuration values, or temporary data across jobs and steps in CI/CD workflows. These variables are critical for managing secrets, configuring build environments, and ensuring secure handling of sensitive data.

Types of Environment Variables

1. GitHub-Defined Variables: Automatically available in workflows (e.g., GITHUB_TOKEN, GITHUB_REPOSITORY, GITHUB_SHA).

2. Custom Environment Variables: Defined and managed within the workflow (env key in jobs or steps).

3. Secrets: Encrypted environment variables that are defined and stored in GitHub Secrets (e.g., API keys, database credentials).

1. GitHub-Defined Environment Variables

GitHub provides built-in environment variables that are useful for workflow metadata and GitHub-specific actions:

2. Custom Environment Variables

Custom environment variables are defined within the workflow using the env key at the job level or step level:

Example Workflow with Custom Environment Variables:

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name: CI Workflow
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on:
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  push:
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    branches:
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     - main
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jobs:
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  build:
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    runs-on: ubuntu-latest
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    env:
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      NODE_ENV: production
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      API_URL: https://api.example.com
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    steps:
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     - name: Checkout Repository
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        uses: actions/checkout@v3
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     - name: Setup Node.js
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        uses: actions/setup-node@v3
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        with:
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          node-version: 16
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     - name: Install Dependencies
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        run: npm install
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     - name: Run Tests
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        run: npm test

In this example:

NODE_ENV and API_URL are custom environment variables.

3. Using Secrets as Environment Variables

GitHub Secrets are encrypted environment variables that are useful for storing sensitive information like API keys, tokens, or credentials.

Defining a Secret:

1. Navigate to the Settings tab of your repository.

2. Go to Secrets.

3. Add a new secret (e.g., MY_API_KEY).

Example Using Secrets:

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name: Deploy Workflow
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on:
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  push:
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    branches:
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     - main
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jobs:
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  deploy:
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    runs-on: ubuntu-latest
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    env:
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      API_KEY: ${{ secrets.MY_API_KEY }}
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    steps:
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     - name: Checkout Repository
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        uses: actions/checkout@v3
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     - name: Deploy to Production
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        run: ./deploy.sh --api-key ${{ env.API_KEY }}

In this case, MY_API_KEY is securely accessed via the GitHub Secrets system.

4. Accessing Environment Variables in Steps

You can access both custom environment variables and secrets within different steps of a workflow.

Example Access in a Step:

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steps:
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   - name: Print Environment Variables
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    run: |
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      echo "NODE_ENV: $NODE_ENV"
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      echo "API_URL: $API_URL"

or

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steps:
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   - name: Print Secret
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    run: echo "My API Key is: $MY_API_KEY"

5. Conditional Logic with Environment Variables

You can define conditional logic based on the value of environment variables.

Example: Conditional Step Execution

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jobs:
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  deploy:
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    runs-on: ubuntu-latest
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    env:
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      DEPLOY_ENV: production
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    steps:
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     - name: Check Deployment Environment
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        run: |
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          if [ "$DEPLOY_ENV" == "production" ]; then
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            echo "Deploying to production"
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          else
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            echo "Not deploying to production"
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          fi

Best Practices for Using Environment Variables

1. Use Secrets for Sensitive Data: Never hard-code sensitive information into workflows. Use encrypted secrets for storing API keys, tokens, or credentials.

2. Limit Access: Use permissions in workflows to restrict which environment variables are exposed to specific steps or jobs.

3. Environment Variables in Matrix Testing: Use dynamic values in environment variables to handle different configurations or matrix testing scenarios.

4. Avoid Hardcoding: Always define environment variables declaratively within the workflow YAML file for maintainability.

5. Debugging with Debug Logs: Enable debugging (ACTIONS_STEP_DEBUG) for detailed information on environment variables in use.

Summary

By leveraging environment variables effectively, GitHub Actions ensure secure, flexible, and dynamic CI workflows.