gh-act-sandbox

Sample project demonstrating how to safely run and test GitHub Actions locally with act in local environment before check-in the code.

GitHub Actions + act + Terraform: Safe Local CI/CD Sandbox

✅ Test GitHub Actions locally.
🔐 Avoid cloud costs.
🧪 Validate functional changes safely.
🖥️ Works on private environments.

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🧩 What Is This?

This repository demonstrates how to:

• Use act to run GitHub Actions locally.
• Test Terraform workflows safely without applying real infrastructure.
• Work in secure, private, or self-hosted runner environments.
• Validate modules, backends, and plans with dummy credentials and local state.

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🔧 Prerequisites

• Docker installed locally
• act installed (docs)
• Terraform CLI installed (>= 1.3.0)
• Linux or macOS (Windows via WSL works too)
• Optional: self-hosted GitHub Actions runner

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🏗️ Repository Structure

.
├── .github/workflows/terraform.yml # GitHub Actions workflow
├── main.tf # Terraform example
├── backend.tf # Local backend config
├── variables.tf # Input variables
├── .secrets.dummy # Fake credentials for act
└── README.md

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## 🚀 Running Locally with `act`

### 🧪 Dry Run Plan

```bash
act workflow_dispatch \
  -P ubuntu-latest=ghcr.io/catthehacker/ubuntu:act-latest \
  --secret-file .secrets.dummy \
  --env DRY_RUN=true

✅ No real cloud infra is touched! Uses local backend and fake secrets.

💡 Tips for Safe Testing

Scenario	Recommendation
Avoid real infra changes	Use terraform plan, local backend, dummy secrets
Test apply logic	Wrap in if: env.DRY_RUN != 'true'
Network-sensitive	Run with --bind or isolate Docker network
Debug failures	Add --verbose to act or run in bash container

📦 Why This Matters

act enables fast, cost-free testing of GitHub Actions workflows. Combined with Terraform and local backends, it lets you:

• Catch errors early

• Avoid cloud billing

• Safely debug changes

🔧 Commands

🔧 Category	🧪 Command	💬 Description
Run default workflow	act	Runs default event (push) using default runner (ubuntu-latest)
Run specific event	act pull_request	Simulates a pull_request event
	act workflow_dispatch	Simulates a workflow_dispatch (manual trigger)
Run specific job	act -j terraform	Runs only the terraform job
Use custom runner image	act -P ubuntu-latest=ghcr.io/catthehacker/ubuntu:act-latest	Uses a GitHub-hosted runner-like Docker image
Use secrets inline	act -s GITHUB_TOKEN=mytoken -s ARM_CLIENT_ID=fake	Passes secrets directly in the command
Use secrets from file	act --secret-file .secrets.dummy	Loads secrets from a file
Set env variables	act --env DRY_RUN=true	Sets environment variable DRY_RUN=true
Specify workflow file	act -W .github/workflows/terraform.yml	Explicitly runs a specific workflow file
Verbose/debug mode	act --verbose	Enables verbose output for debugging
Mount local volume	act -v $(pwd):/github/workspace	Mounts local working directory inside the container
Run from Docker manually	docker run --rm -it -v $(pwd):/github/workspace your-act-image act workflow_dispatch	Manually runs act from a Docker container

• Test from secure/self-hosted runners

📚 Resources

• act GitHub Repo

• [GitHub Actions Docs] (https://docs.github.com/en/actions)

• [Terraform Docs] (https://developer.hashicorp.com/terraform/docs)

License

This project is licensed under the MIT - see the LICENSE file for details.

Please replace https://github.com/premkumar-palanichamy/gh-act-sandbox with the URL of your Git repository if you have one. This README provides a comprehensive guide to your Git Mirroring concept and can be extended or modified as needed.

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