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

| Action | Command | |--------|---------| | Create codespace | gh codespace create -r owner/repo | | List codespaces | gh codespace list | | Open in VS Code | gh codespace code -c <name> | | Open in browser | gh codespace view -c <name> -w | | SSH into codespace | gh codespace ssh -c <name> | | Stop codespace | gh codespace stop -c <name> | | Delete codespace | gh codespace delete -c <name> |

Machine Types

| Type | vCPUs | RAM | Storage | Best For | |------|-------|-----|---------|----------| | Basic | 2 | 8GB | 32GB | Simple projects, docs | | Standard | 4 | 16GB | 32GB | Most development | | Large | 8 | 32GB | 64GB | Full-stack, multiple services | | XL | 16 | 64GB | 128GB | Data science, ML | | GPU | 4+ | 16GB+ | 64GB+ | ML training, CUDA |

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

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

Troubleshooting

| Issue | Solution | |-------|----------| | Slow startup | Enable prebuilds | | Out of storage | Delete unused files, increase disk | | Extension not working | Check devcontainer extensions config | | Port not accessible | Check forwardPorts configuration | | Environment variables missing | Verify secrets are set |

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