Deploying Rails 8 with Kamal: A Practical Guide

Kamal makes deploying Rails apps to bare metal servers incredibly simple. Here's how to get started.

Prerequisites

• A VPS with Docker installed (Hetzner, DigitalOcean, etc.)
• A domain pointed at your server's IP
• SSH key access

Initial Setup

kamal init

This generates a deploy.yml file. Key settings to configure:

service: myapp
image: myregistry/myapp

servers:
  web:
    hosts:
      - 123.456.789.0
    labels:
      traefik.http.routers.myapp.rule: Host(`myapp.com`)

First Deploy

kamal setup

This does everything: pulls images, sets up Docker, configures SSL via Let's Encrypt, and starts your app.

Zero-Downtime Deploys

Kamal uses rolling deploys by default. New containers start before old ones stop:

kamal deploy

Database

For PostgreSQL, use a managed database (Railway, Supabase) or run it on a separate server. Kamal handles the app containers — not the database.

Monitoring

Check your app health:

kamal app logs
kamal app status

Kamal brings Heroku-like simplicity to your own infrastructure.