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Zil Norvilis
Zil Norvilis

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Fire Your DevOps Team: A Solo Dev’s Guide to Kamal 2

#rails #docker #devops #deployment

The Deployment Dilemma

For the last decade, developers have been stuck between a rock and a hard place.

  1. The PaaS Trap (Heroku, Render, Fly): extremely easy to use, but the moment you need more than 512MB of RAM, the price jumps from $7 to $50 to $200. You pay a "convenience tax."
  2. The Cloud Maze (AWS, Kubernetes): Infinite power and cheaper raw resources, but you need a PhD in IAM roles, VPCs, and Load Balancers to serve a "Hello World" app.

Enter Kamal.
Created by Basecamp (the makers of Rails), Kamal bridges this gap. It gives you the ownership and low cost of raw VPS (Virtual Private Server) hardware, with the ease of a git push style deployment.

With the release of Kamal 2, it is finally ready for the masses. Here is how I deployed a production-ready app to a $5 Hetzner server in under 10 minutes.

What is Kamal?

Kamal is essentially "Capistrano for Containers."

It runs locally on your laptop. When you type kamal deploy, it:

  1. Builds your Docker image locally (or on a builder).
  2. Pushes it to a registry (like Docker Hub or GitHub Packages).
  3. SSH's into your server(s).
  4. Pulls the new image.
  5. Boots it up alongside the old version.
  6. Switches traffic over (Blue/Green deployment) using its built-in Proxy.
  7. Kills the old version.

There is no "Master Node." There is no Kubernetes cluster state to manage. If you lose your laptop, your server keeps running.

The Hardware: The $5 Powerhouse

Go to Hetzner (or DigitalOcean/Linode) and buy a cheap VPS.
For roughly $5/month, you can get an ARM server with 2 vCPUs and 4GB of RAM.

On Heroku, a "Performance" dyno with similar specs would cost you $250+/month.
That is the math that makes Kamal a no-brainer for solo developers.

The Guide: From Zero to SSL

1. Installation

Assuming you have Docker running locally:

gem install kamal
kamal init
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2. Configuration (config/deploy.yml)

Kamal 2 simplified configuration massively. Here is all you need:

service: my-app
image: your-username/my-app

servers:
  web:
    - 123.45.67.89 # Your VPS IP address

# The Registry where your Docker images live
registry:
  server: ghcr.io
  username: your-username
  password:
    - KAMAL_REGISTRY_PASSWORD

# Inject environment variables
env:
  secret:
    - RAILS_MASTER_KEY
    - POSTGRES_PASSWORD
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3. The Magic of Kamal 2: The Proxy

In Kamal 1, you had to configure Traefik manually to handle SSL. It was confusing.
Kamal 2 includes kamal-proxy by default.

It automatically handles:

  • Zero-downtime deployments: It holds requests while your app restarts.
  • Auto-SSL: It talks to Let's Encrypt automatically to give you HTTPS.

You just add this to your deploy.yml:

proxy:
  ssl: true
  host: myapp.com
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4. What about the Database?

For a true "One Person" setup, we don't want to pay for a Managed Database (RDS). We want the DB on the same $5 server.

Kamal handles this via Accessories. You can tell Kamal to boot a Postgres container and manage it for you.

accessories:
  db:
    image: postgres:15
    host: 123.45.67.89
    port: 5432
    env:
      POSTGRES_DB: my_app_production
      POSTGRES_USER: my_app
      POSTGRES_PASSWORD:
        - POSTGRES_PASSWORD
    files:
      # Persist data to the host disk so it survives restarts!
      - db_data:/var/lib/postgresql/data
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5. The Launch

The moment of truth.

kamal setup
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This single command will:

  1. SSH into your VPS and install Docker.
  2. Start your Database accessory.
  3. Start the Kamal Proxy.
  4. Build your app.
  5. Start your app.
  6. Issue an SSL certificate.

In about 3-5 minutes, your app is live at https://myapp.com.

Day 2 Operations: Sleep Easy

"But what if I deploy a bug?"

kamal rollback
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Kamal keeps the old containers around (stopped). A rollback just switches the proxy pointer back to the old container. It takes 10 seconds.

"What if I need to run a Rails console?"

kamal app exec -i 'bin/rails console'
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You are instantly dropped into a remote console session on your server.

Summary

The "DevOps Guy" used to be a mandatory hire.
With Kamal 2, the barrier to entry for owning your own infrastructure has collapsed.

You don't need Kubernetes. You don't need AWS Lambda. You need a Linux box, an SSH key, and Kamal.

Fire your DevOps team (or rather, stop trying to be one). Get back to coding.

Are you still paying the PaaS premium? Let me know why in the comments! 👇

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