Dockerize the application

Base Dockerfile, entrypoint.sh, and docker-compose.yml on https://docs.docker.com/samples/rails/
Ignore all temporary folders, .git, and non-necessary files on .dockerignore based on https://codefresh.io/docker-tutorial/not-ignore-dockerignore-2/

Create .env file with POSTGRES_USER and POSTGRES_PASSWORD used for postgres on docker-compose.yml
I need to spend some time seeing what solution I can use for environment variables in docker locally and production
Since at the moment I have both .env and environment_variables.rb

Add host:db to database.yml in order for the postgres port to be available on docker

.dockerignore

@@ -0,0 +1,14 @@
+.git
+/tmp
+/log
+
+.byebug_history
+.gitignore
+.dockerignore
+.rubocop.yml
+.ruby-version
+README.rdoc
+
+/config/secrets.yml
+/config/environment_variables.rb
+.env

.env.example

@@ -0,0 +1,5 @@
+# Used for docker-compose.yml.
+# POSTGRES_USER and POSTGRES_PASSWORD need to match ones in database.yml
+
+POSTGRES_USER=
+POSTGRES_PASSWORD=

.gitignore

@@ -25,3 +25,4 @@
 #ignore config secrets and environment variables
 /config/secrets.yml
 /config/environment_variables.rb
+.env

Dockerfile

@@ -0,0 +1,18 @@
+# Based on https://docs.docker.com/samples/rails/
+
+# syntax=docker/dockerfile:1
+FROM ruby:3.0.1
+RUN apt-get update -qq && apt-get install -y nodejs postgresql-client
+WORKDIR /myapp
+COPY Gemfile /myapp/Gemfile
+COPY Gemfile.lock /myapp/Gemfile.lock
+RUN bundle install
+
+# Add a script to be executed every time the container starts.
+COPY entrypoint.sh /usr/bin/
+RUN chmod +x /usr/bin/entrypoint.sh
+ENTRYPOINT ["entrypoint.sh"]
+EXPOSE 3000
+
+# Configure the main process to run when running the image
+CMD ["rails", "server", "-b", "0.0.0.0"]

config/database.yml

@@ -1,15 +1,14 @@
-defaults: &default
+default: &default
   adapter: postgresql
   encoding: unicode
+  host: db
   username: <%= ENV["POSTGRES_USERNAME"] %>
   password: <%= ENV["POSTGRES_PASSWORD"] %>
   database: <%= ENV["POSTGRES_DB"] %>
+  pool: 5
 
 test:
-  adapter: postgresql
-  encoding: unicode
-  username: <%= ENV["POSTGRES_USERNAME"] %>
-  password: <%= ENV["POSTGRES_PASSWORD"] %>
+  <<: *default
   database: <%= ENV["POSTGRES_TEST_DB"] %>
 
 development:

docker-compose.yml

@@ -0,0 +1,19 @@
+# Based on https://docs.docker.com/samples/rails/
+
+version: "3.9"
+services:
+  db:
+    image: postgres
+    volumes:
+      - ./tmp/db:/var/lib/postgresql/data
+    env_file:
+      - .env
+  web:
+    build: .
+    command: bash -c "rm -f tmp/pids/server.pid && bundle exec rails s -p 3000 -b '0.0.0.0'"
+    volumes:
+      - .:/myapp
+    ports:
+      - "3000:3000"
+    depends_on:
+      - db

entrypoint.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+set -e
+
+# Remove a potentially pre-existing server.pid for Rails.
+rm -f /myapp/tmp/pids/server.pid
+
+# Then exec the container's main process (what's set as CMD in the Dockerfile).
+exec "$@"
+
+# Based on https://docs.docker.com/samples/rails/