name: codespaces description: Create, manage, and optimize GitHub Codespaces cloud development environments. Configure devcontainers, manage resources, and streamline cloud-based development. Use when setting up cloud development environments, configuring devcontainers, or managing Codespaces. Triggers on codespace, devcontainer, cloud IDE, remote development, development environment, container development.

GitHub Codespaces

Cloud development environments that work anywhere.

Prerequisites

• GitHub Account: With Codespaces access
• gh CLI: Install from https://cli.github.com/
• Authentication: Run gh auth login

Quick Reference

Core Commands

Machine Types

DevContainer Configuration

Directory Structure

.devcontainer/
+-- devcontainer.json           # Default configuration
+-- web-frontend/
|   +-- devcontainer.json       # Frontend-specific
+-- backend-api/
|   +-- devcontainer.json       # Backend-specific
+-- data-science/
    +-- devcontainer.json       # Data science config

Basic devcontainer.json

{
  "name": "Project Dev Environment",
  "image": "mcr.microsoft.com/devcontainers/universal:2",
  "features": {
    "ghcr.io/devcontainers/features/node:1": {},
    "ghcr.io/devcontainers/features/python:1": {}
  },
  "customizations": {
    "vscode": {
      "extensions": [
        "GitHub.copilot",
        "ms-python.python"
      ]
    }
  },
  "postCreateCommand": "npm install",
  "forwardPorts": [3000, 5000]
}

Lifecycle Scripts

postCreateCommand

Runs once when container is created:

"postCreateCommand": "npm install && npm run setup"

postStartCommand

Runs every time codespace starts:

"postStartCommand": "npm run dev:services"

postAttachCommand

Runs when VS Code attaches:

"postAttachCommand": "echo 'Welcome! Run npm start to begin.'"

Secrets Management

Setting Secrets

# For a specific repo
gh secret set API_KEY --repo owner/repo

# For Codespaces specifically
gh secret set DB_PASSWORD --app codespaces

# For user (all Codespaces)
gh secret set NPM_TOKEN --user

Using Secrets in devcontainer.json

{
  "containerEnv": {
    "DATABASE_URL": "${localEnv:DATABASE_URL}"
  },
  "secrets": {
    "API_KEY": {
      "description": "API key for external service"
    }
  }
}

Port Forwarding

Automatic Forwarding

{
  "forwardPorts": [3000, 5000, 8080],
  "portsAttributes": {
    "3000": {
      "label": "Frontend",
      "onAutoForward": "openBrowser"
    },
    "5000": {
      "label": "API",
      "onAutoForward": "notify"
    }
  }
}

Manual Forwarding

gh codespace ports forward 3000:3000 -c <codespace-name>

Common Workflows

Quick Start New Feature

# Create codespace for feature branch
gh codespace create -r owner/repo -b feature-branch -m standardLinux

# Open in VS Code
gh codespace code

PR Review in Codespace

# Create codespace from PR
gh codespace create -r owner/repo --branch pr-branch

# Or use the PR directly
gh pr checkout 123
gh codespace create

Share Environment

# Export port with visibility
gh codespace ports visibility 3000:public -c <name>

# Get shareable URL
gh codespace ports -c <name>

Performance Optimization

Prebuilds

Enable prebuilds for faster startup:

// .github/codespaces/prebuild.json
{
  "triggers": {
    "branches": ["main", "develop"],
    "paths": ["package.json", ".devcontainer/**"]
  }
}

Dotfiles Repository

Configure personal dotfiles in GitHub Settings > Codespaces.

Cost Management

Auto-stop Settings

Configure in GitHub Settings > Codespaces:

• Default idle timeout: 30 minutes
• Retention period: 7 days

Best Practices

1. Stop when not in use: gh codespace stop
2. Delete completed work: gh codespace delete
3. Use appropriate machine size: Don't over-provision
4. Enable prebuilds: Faster startup, less billing

Troubleshooting

When to Use This Skill

• Setting up cloud development environments
• Configuring devcontainers for team consistency
• Managing Codespaces via CLI
• Optimizing development environment performance
• Sharing development environments
• PR reviews in isolated environments