Configure Rails for Production

Setup a webserver

Rails runs best in production with a reverse-proxy setup. Let’s configure nginx to serve static assets directly, handle compression, and proxy connections into rails through puma.


Add the following to your boxfile.yml to make nginx available to the runtime:

  # add nginx package
    - nginx

Now add the following nginx config file into your project, at config/nginx.conf:

worker_processes 1;
daemon off;

events {
    worker_connections 1024;

http {
    include /data/etc/nginx/mime.types;
    sendfile on;

    gzip              on;
    gzip_http_version 1.0;
    gzip_proxied      any;
    gzip_min_length   500;
    gzip_disable      "MSIE [1-6]\.";
    gzip_types        text/plain text/xml text/css

    # Proxy upstream to the puma process
    upstream rails {

    # Configuration for Nginx
    server {

        # Listen on port 8080
        listen 8080;

        root /app/public;

        try_files $uri/index.html $uri @rails;

        # Proxy connections to rails
        location @rails {
            proxy_pass         http://rails;
            proxy_redirect     off;
            proxy_set_header   Host $host;


Add puma to your Gemfile:

gem 'puma', '~> 3.0'

Now add the following puma config file into your project, at config/puma.rb:

# Puma can serve each request in a thread from an internal thread pool.
# The `threads` method setting takes two numbers a minimum and maximum.
# Any libraries that use thread pools should be configured to match
# the maximum value specified for Puma. Default is set to 5 threads for minimum
# and maximum, this matches the default thread size of Active Record.
threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }.to_i
threads threads_count, threads_count

# Specifies the `port` that Puma will listen on to receive requests, default is 3000.
port        ENV.fetch("PORT") { 3000 }

# Specifies the `environment` that Puma will run in.
environment ENV.fetch("RAILS_ENV") { "development" }

# Specifies the number of `workers` to boot in clustered mode.
# Workers are forked webserver processes. If using threads and workers together
# the concurrency of the application would be max `threads` * `workers`.
# Workers do not work on JRuby or Windows (both of which do not support
# processes).
# workers ENV.fetch("WEB_CONCURRENCY") { 2 }

# Use the `preload_app!` method when specifying a `workers` number.
# This directive tells Puma to first boot the application and load code
# before forking the application. This takes advantage of Copy On Write
# process behavior so workers use less memory. If you use this option
# you need to make sure to reconnect any threads in the `on_worker_boot`
# block.
# preload_app!

# The code in the `on_worker_boot` will be called if you are using
# clustered mode by specifying a number of `workers`. After each worker
# process is booted this block will be run, if you are using `preload_app!`
# option you will want to use this block to reconnect to any threads
# or connections that may have been created at application boot, Ruby
# cannot share connections between processes.
# on_worker_boot do
#   ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
# end

# Allow puma to be restarted by `rails restart` command.
plugin :tmp_restart

IMPORTANT: The puma configuration above is a minimal configuration sufficient to run your app. We will cover advanced configuration tuning in a later guide.

Add webs and workers

For your app to run in production, at the very least you’ll need a web component. There is also a good chance you’ll want some sort of job queue to send emails, process jobs, etc. These would all be ideal tasks for a worker component.

Specify web components

You can have as many web components as your app needs by simply adding them to your existing boxfile.yml:

# add a web component and give it a "start" command
    nginx: nginx -c /app/config/nginx.conf
    puma: bundle exec puma -C /app/config/puma.rb

In the above snippet main is the name of web component and can be anything you choose (it is only used as a unique identifier).

Specify worker components

You can have as many worker components as your app needs by simply adding them to your existing boxfile.yml:

# add a worker component and give it a "start" command
  start: sidekiq

In the above snippet main is the name of the worker component and can be anything you choose (it is only used as a unique identifier).

Add Writable Directories

By default, webs and workers run in a read only environment. Rails will need certain directories available to write to for things like log output, temporary files, etc.

You’ll need to specify these writable directories per component by updating your existing boxfile.yml:

  # add writable dirs to your web component
    - tmp
    - log

  # add writable dirs to your worker component
    - tmp
    - log

You can visit the writable_dirs doc for more information about this node.

Add Streaming Logs

Although our app is now able to write it’s logs to log files, if you want it to stream those logs to the nanobox dashboard we’ll need to add a log_watch path to the boxfile:

  # the path to a logfile you want streamed to the nanobox dashboard
    rails: 'log/production.log'

  # the path to a logfile you want streamed to the nanobox dashboard
    sidekiq: 'path/to/sidekiq/log.file'

You can visit the log_watch doc for more information about this node.

Compile Assets

We can have rails compile assets during the deploy process by adding an extra step:

    - rake assets:precompile RAILS_ENV=production

Migrate Data

To migrate data as part of the deploy process you can add a before_live hook, which will run just before the new instances are started.

Add a deploy hook

Run a rake task each time we deploy. In your existing boxfile.yml add the following code:

      - rake db:setup_or_migrate

Add a rake task

You’ll need to add a custom rake task that will either setup your database on first deploy, or run migrations for subsequent deploys. You could, for example, create a lib/tasks/db.rake file that contained the following:

namespace :db do
  desc 'Setup the db or migrate depending on state of db'
  task setup_or_migrate: :environment do
    rescue ActiveRecord::NoDatabaseError

NOTE: Your rake task may need to be modified to fit the database you’re using.

Now what?

With your app configured for running in production, whats next? Think about what else your app might need and hopefully the topics below will help you get started with the next steps of your development!