try112

Warn if we can't read the yaml to create database tasks
rails/rails#36560

Gemfile

@@ -8,6 +8,7 @@ gem 'rails', '~> 6.0.0'
 # Use postgresql as the database for Active Record
 gem 'pg', '>= 0.18', '< 2.0'
 # Use Puma as the app server
+gem 'mysql2'
 gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5'

Gemfile.lock

@@ -99,6 +99,7 @@ GEM
     mini_portile2 (2.4.0)
     minitest (5.13.0)
     msgpack (1.3.1)
+    mysql2 (0.5.2)
     nio4r (2.5.2)
     nokogiri (1.10.7)
       mini_portile2 (~> 2.4.0)
@@ -206,6 +207,7 @@ DEPENDENCIES
   capybara (>= 2.15)
   jbuilder (~> 2.7)
   listen (>= 3.0.5, < 3.2)
+  mysql2
   pg (>= 0.18, < 2.0)
   puma (~> 4.3)
   rails (~> 6.0.0)

config/database.yml

@@ -1,31 +1,21 @@
-# PostgreSQL. Versions 9.3 and up are supported.
-#
-# Install the pg driver:
-#   gem install pg
-# On macOS with Homebrew:
-#   gem install pg -- --with-pg-config=/usr/local/bin/pg_config
-# On macOS with MacPorts:
-#   gem install pg -- --with-pg-config=/opt/local/lib/postgresql84/bin/pg_config
-# On Windows:
-#   gem install pg
-#       Choose the win32 build.
-#       Install PostgreSQL and put its /bin directory on your path.
-#
-# Configure Using Gemfile
-# gem 'pg'
-#
-default: &default
+mysql: &mysql
+  adapter: mysql2
+  encoding: utf8mb4
+  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
+  username: root
+  password:
+  host: db_mysql
+
+postgresql: &postgresql
   adapter: postgresql
   encoding: unicode
-  # For details on connection pooling, see Rails configuration guide
-  # https://guides.rubyonrails.org/configuring.html#database-pooling
   pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
-  host: db
+  host: db_postgresql
   user: <%= ENV.fetch("POSTGRES_USER") %>
   password: <%= ENV.fetch("POSTGRES_PASSWORD") %>
 
 development:
-  <<: *default
+  <<: *<%= ENV.fetch("DB") { 'postgresql' } %>
   database: app_development
 
   # The specified database role being used to connect to postgres.
@@ -59,7 +49,7 @@ development:
 # re-generated from your development database when you run "rake".
 # Do not set this db to the same as development or production.
 test:
-  <<: *default
+  <<: *<%= ENV.fetch("DB") { 'postgresql' } %>
   database: app_test
 
 # As with config/credentials.yml, you never want to store sensitive information,
@@ -82,7 +72,7 @@ test:
 #     url: <%= ENV['DATABASE_URL'] %>
 #
 production:
-  <<: *default
+  <<: *<%= ENV.fetch("DB") { 'postgresql' } %>
   database: app_production
   username: app
   password: <%= ENV['APP_DATABASE_PASSWORD'] %>

docker-compose.yml

@@ -12,16 +12,25 @@ services:
     environment:
       - POSTGRES_USER
       - POSTGRES_PASSWORD
-  db:
+  db_postgresql:
     image: postgres:12.0-alpine
     volumes:
       - pgsqldb:/var/lib/postgresql/data
     environment:
       - POSTGRES_USER
       - POSTGRES_PASSWORD
+  db_mysql:
+    image: mysql:8.0.16
+    command: --default-authentication-plugin=mysql_native_password
+    volumes:
+      - mysqldb:/var/lib/mysql
+    environment:
+      - MYSQL_ALLOW_EMPTY_PASSWORD=yes
 
 volumes:
   pgsqldb:
     driver: local
+  mysqldb:
+    driver: local
   bundle:
     driver: local

scripts/parse_database_yml.rb

@@ -0,0 +1,2 @@
+yml = ERB.new(File.read(Rails.root.join('config/database.yml')))
+print yml.result