Rails 8 Production Setup with Dokku Guide

The Challenge: Modernizing Rails Deployment

When I recently needed to deploy my Rails 8 application with multiple databases, I faced a common dilemma: choosing between expensive managed solutions and complex self-managed servers. My requirements were specific:

Multiple PostgreSQL databases for different concerns
SSL certificate management
Automated deployment pipeline
Cost-effective hosting
Easy database management
Background job processing

Let me walk you through how I solved this using Dokku.

Setting Up Our Foundation

First, let's prepare our server. I chose a 2GB RAM VPS - here's why:

Dokku needs about 1GB RAM to operate smoothly
Rails 8 with Puma and background jobs needs the other 1GB
Anything less resulted in occasional memory issues during asset compilation

Initial Server Configuration

SSH into your server and install Dokku:

wget -NP . https://dokku.com/install/v0.35.13/bootstrap.sh
sudo DOKKU_TAG=v0.35.13 bash bootstrap.sh

After countless deployments, I've found this version to be particularly stable with Rails 8.

The Database Architecture

One of Rails 8's strengths is its multi-database support. In my setup, I separated concerns into four databases:

# Create our databases
dokku postgres:create rails_primary_db
dokku postgres:create rails_cache_db
dokku postgres:create rails_queue_db
dokku postgres:create rails_cable_db

Here's why I chose this architecture:

Primary DB: Core application data
Cache DB: Session and cache storage
Queue DB: Background job management
Cable DB: Action Cable subscriptions

The Magic of Database Linking

This is where things get interesting. When linking databases, Dokku generates unique environment variables:

# Link each database and capture the environment variable names
dokku postgres:link rails_primary_db your-rails-app
# Returns: DATABASE_URL=postgres://...

dokku postgres:link rails_cache_db your-rails-app
# Returns: DOKKU_POSTGRES_AQUA_URL=postgres://...

dokku postgres:link rails_queue_db your-rails-app
# Returns: DOKKU_POSTGRES_BLACK_URL=postgres://...

dokku postgres:link rails_cable_db your-rails-app
# Returns: DOKKU_POSTGRES_BLUE_URL=postgres://...

Rails 8 Configuration Magic

Here's how I configured my Rails 8 application to use these databases. In config/database.yml:

production:
  primary: &primary_production
    <<: *default
    database: <%= ENV['DATABASE_URL'] || 'rails_primary_db' %>
    url: <%= ENV['DATABASE_URL'] %>

  cache:
    <<: *primary_production
    database: <%= ENV['DOKKU_POSTGRES_AQUA_URL'] || 'rails_cache_db' %>
    migrations_paths: db/cache_migrate
    url: <%= ENV['DOKKU_POSTGRES_AQUA_URL'] %>

  queue:
    <<: *primary_production
    database: <%= ENV['DOKKU_POSTGRES_BLACK_URL'] || 'rails_queue_db' %>
    migrations_paths: db/queue_migrate
    url: <%= ENV['DOKKU_POSTGRES_BLACK_URL'] %>

  cable:
    <<: *primary_production
    database: <%= ENV['DOKKU_POSTGRES_BLUE_URL'] || 'rails_cable_db' %>
    migrations_paths: db/cable_migrate
    url: <%= ENV['DOKKU_POSTGRES_BLUE_URL'] %>

The Deployment Pipeline

Create a Procfile in your Rails root:

web: bin/rails server -p $PORT -e $RAILS_ENV
worker: bin/jobs
release: bundle exec rails db:migrate 2>/dev/null || bundle exec rails db:setup

I learned the hard way that the release command needs error handling for first deployments, hence the 2>/dev/null || bundle exec rails db:setup pattern.

Environment Configuration

Rails 8 needs specific environment variables. Here's my production setup:

# Rails essentials
dokku config:set your-rails-app RAILS_ENV=production
dokku config:set your-rails-app RACK_ENV=production
dokku config:set your-rails-app RAILS_MASTER_KEY=$(cat config/credentials/production.key)

# Rails 8 specifics
dokku config:set your-rails-app RAILS_SERVE_STATIC_FILES=true
dokku config:set your-rails-app RAILS_LOG_TO_STDOUT=true

Git Deployment Setup

Configure your local repository:

# Add Dokku remote
git remote add production dokku@your-server-ip:your-rails-app

# Verify remote addition
git remote show production

# Set deployment branch
dokku git:set your-rails-app deploy-branch main

SSL Configuration

Rails 8 expects HTTPS in production. Here's how to set it up with Let's Encrypt:

# Install the plugin
sudo dokku plugin:install https://github.com/dokku/dokku-letsencrypt.git

# Configure your domain
dokku domains:clear-global
dokku domains:set your-rails-app yourdomain.com

# Setup SSL
dokku letsencrypt:set your-rails-app email your@email.com
dokku letsencrypt:enable your-rails-app
dokku letsencrypt:cron-job --add

Deployment and Monitoring

Deploy your application:

git push production main

Monitor your deployment:

# Real-time logs
dokku logs your-rails-app -t

# Process status
dokku ps:report your-rails-app

# Database status
dokku postgres:info rails_primary_db

Troubleshooting Common Rails 8 Issues

During my deployments, I encountered several Rails 8-specific issues:

Asset Compilation Failures

 # Force a clean asset compilation
 dokku run your-rails-app bundle exec rails assets:clobber assets:precompile

Database Migration Issues

 # Run migrations manually if needed
 dokku run your-rails-app bundle exec rails db:migrate

Worker Process Management

 # Restart workers after config changes
 dokku ps:restart your-rails-app worker

Maintenance Tips

Based on my experience, here are some crucial maintenance practices:

Database Backups

# Backup all databases
for db in primary cache queue cable; do
  dokku postgres:export rails_${db}_db > ${db}_backup.dump
done

Performance Monitoring

Monitor your Rails 8 application's health:

# Check memory usage
dokku ps:report your-rails-app

# View error logs
dokku logs your-rails-app -t | grep ERROR

Conclusion

Deploying Rails 8 with Dokku has been a game-changer for my development workflow. The combination of Rails 8's robust multi-database support and Dokku's Heroku-like deployment experience has made managing production applications both cost-effective and developer-friendly.

Remember to:

Keep your Rails master key secure
Regularly backup all databases
Monitor worker processes
Keep an eye on memory usage

The setup might seem extensive, but once configured, deployments become as simple as git push production main. Feel free to reach out if you encounter any Rails 8-specific deployment challenges!

This guide reflects my real-world experience deploying Rails 8 applications with Dokku. As you work with this setup, you'll likely discover additional optimizations specific to your use case.

Happy deploying!