docker + rails + nginx + webpacker + ssl + action cable + active storage

There are various ways to launch rails with docker, but I couldn't find one that uses webpacker, Action cable, and Active storage, so I summarized them.

rails settings

Gemfile First, since postgresql and redis are used as the database, describe them in the Gemfile. If you don't use action cable, you can just use postgresql.


gem 'redis'
gem 'pg'

database.yml Next, we will set up the connection of postgresql. We will set usernames and passwords as environment variables later.


  adapter: postgresql
  encoding: unicode
  username: <%= ENV.fetch("POSTGRES_USER") %>
  password: <%= ENV.fetch("POSTGRES_PASSWORD") %>
  pool: 5
  host: db
  database: <%= ENV.fetch("DB_NAME") %>

production.rb Next, set the ssl of the production environment. Uncomment the next part. This will always set the ssl setting. Since static files are delivered by nginx, static file delivery settings are not set.


  config.force_ssl = true

puma.rb Next, we will set up puma. Here, in order to set to communicate with socket, the PORT setting is deleted and the bottom two lines are added.


max_threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }
min_threads_count = ENV.fetch("RAILS_MIN_THREADS") { max_threads_count }
threads min_threads_count, max_threads_count

environment ENV.fetch("RAILS_ENV") { "development" }

pidfile ENV.fetch("PIDFILE") { "tmp/pids/" }

plugin :tmp_restart

app_root = File.expand_path("../..", __FILE__)
bind "unix://#{app_root}/tmp/sockets/puma.sock"

master.key Next, set master.key. It is required along with credentials that can encrypt and share API keys and so on. You can give the API key etc. to github etc. in an encrypted state. Instead, if you do not share master.key, you will not be able to combine it and an error will occur at the time of deployment, so set it.

vim config/master.key
#Local config/master.Please copy and paste the key

sockets If the sockets directory does not exist under tmp, create it because an error may occur when starting puma unless you create it.

cd tmp
mkdir sockets
touch sockets/.keep

Docker settings

Please install docker and docker-compose according to your environment.

Download docker-compose file

The files required to build a Rails environment with docker-compose are summarized below.

git clone
#Please go in the directory where Gemfile etc. exists
cd docker-rails
ln docker-compose.yml ../docker-compose.yml
ln .env ../.env

Setting environment variables

Please edit the .env file because the items that need to be changed according to your environment are summarized in the .env file.


POSTGRES_USER=username(ex: postgres)
POSTGRES_PASSWORD=Password (ex: password)
DB_NAME=Database name(ex: app_production)
SERVER_NAME=server name(ex:

Docker build, DB build

docker-compose build
docker-compose run app rake db:migrate

SSL settings

The rails part corresponds to COMPOSE_PROJECT_NAME set in the environment variable. Please set the e-mail address and domain part according to your environment.

sudo docker run --rm   -p 443:443 -p 80:80 --name letsencrypt   -v "rails_certs:/etc/letsencrypt"   -v "rails_certs-data:/var/lib/letsencrypt"   certbot/certbot certonly -n   -m "mail address"   -d domain--standalone --agree-tos

Launch of Docker

docker-compose up -d

You should be able to access it if you have completed the port / DNS settings.

Reference site

Docker + Rails + Puma + Nginx(SSL) + MySQL

Set SSL/TLS with Ubuntu + nginx + LetsEncrypt

Build an HTTPS-enabled proxy server with Docker + Nginx + Let's Encrypt

docker+rails+puma+nginx+postgres (Production ready)

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