Runtimes

HostFn uses a pluggable runtime adapter system. Each runtime adapter handles detection, default configuration, server setup script generation, and process management.

Runtime Detection

When you run hostfn init, HostFn scans your project directory to detect the runtime:

$ hostfn init
✔ Detected nodejs (confidence: 95%)

Node.js Detection

The Node.js detector checks for:

The detector also reads package.json to determine:

• Build command - From scripts.build
• Start command - From scripts.start
• Entry point - Inferred from main field
• Node.js version - From engines.node

Node.js Runtime

The Node.js adapter is the primary supported runtime. It uses:

• nvm for version management
• PM2 for process management (cluster mode, auto-restart, log management)
• npm for dependency installation

Server Setup

When you run hostfn server setup, the Node.js adapter generates a setup script that installs:

1. nvm and the specified Node.js version
2. PM2 globally via npm
3. Nginx web server
4. Certbot for SSL certificates
5. rsync for file transfers
6. build-essential for native npm modules
7. UFW firewall configuration (ports 22, 80, 443)

Optionally:

• Redis (with --redis flag)

PM2 Ecosystem Config

For each deployment, HostFn generates a PM2 ecosystem configuration file:

module.exports = {
  apps: [{
    name: 'my-app-production',
    script: 'dist/index.js',
    instances: 'max',
    exec_mode: 'cluster',
    env: {
      NODE_ENV: 'production',
      PORT: 3000,
      DATABASE_URL: '...',
    },
    error_file: './logs/err.log',
    out_file: './logs/out.log',
    time: true,
    autorestart: true,
    max_restarts: 10,
    min_uptime: '10s',
    max_memory_restart: '1G'
  }]
};

Key features:

• Cluster mode with configurable instances (defaults to "max" for all CPU cores)
• Auto-restart on crashes with max restart limits
• Memory limit restarts (1GB default)
• Timestamped logs in ./logs/ directory
• Environment variables from the server's .env file are injected into the config

Future Runtimes

The runtime adapter interface is designed for extensibility. Planned runtimes include:

Each runtime adapter implements the same interface, so the deployment workflow remains identical regardless of the runtime.