[Rails & Docker & MySQL environment construction] I started the container, but I can't find MySQL ...?


I'm in the middle of creating a portfolio. Since I stumbled immediately in the first environment construction, I will write it including the meaning of the memorandum. I would be happy if it is delivered to beginners who have stumbled in the same place.

Flow so far

Could not find gem 'mysql2 (>= 0.4.4)' in any of the gem sources listed in your Gemfile.


① Install MySQL locally ②bundle install ③ Confirm that Gemfile.lock is created


The root cause was that I used to pollute my environment when I installed MySQL locally. There is a problem with the socket and permissions, and it seems that bundle install did not pull MySQL well.

Therefore, delete all the MySQL directories and install MySQL locally again. After that, it is in the form of bundle install.

Gemfile.lock wasn't working well, so docker-compose up didn't pull mysql. By the way, bundle install didn't create gemfile.lock. (Crying)

Rails × docker says that such a local state can affect. I learned a lot.

The following is the environment / background.

Created file

The Dockerfile and docker-compose.yml look like this.


#Use Ruby
FROM ruby:2.6.6

#UTF character code-Set to 8

#Set Time Zone to Japan
ENV TZ Asia/Tokyo

#Create an app directory directly under the root
RUN mkdir /app

#In the working directory/Move by specifying app

#Share Host Gemfile
COPY Gemfile /app/Gemfile

#Install various packages
#libpq:Required to deploy MySQL with Gem
#sudo:Authority change management
#bundler(Mechanism to install the package described in Gemfile)Install
RUN apt-get update -qq && apt-get install -y build-essential \
	libpq-dev \
	sudo \
	&& gem install bundler:2.0.1

#Install the package described in Gemfile
#Rails 6 in Gemfile.0.3'Is listed
RUN bundle install

#/Share current directory with app
COPY . /app

(It's hard to see because it's full of comments ...)


version: "3"

#Create db and backend containers
    container_name: db
    #Pull the image uploaded to Docker Hub
    image: mysql:latest
    #Environment variable settings
      TZ: Asia/Tokyo #Set TimeZone as well as Dockerfile
      MYSQL_DATABASE: linpy_database #Set database name
      MYSQL_ROOT_PASSWORD: ***** #Set password for root user
      MYSQL_USER: ***** #Define user
      MYSQL_PASSWORD: ***** #Set the password of the above user
    #Specify the path of the configuration file to mount
      - mysql_data:/var/lib/mysql
    #Set port
      - 3307:3306
    #Set IP address
      app_net: #App described later_Set to use the following IPs in the net network space
        ipv4_address: ''

    container_name: backend
    #Execute ComposeFile and specify the path when it is built
    build: ./backend/
    image: backend
    #Run gem to start the server, 0.0.0.Bind to 0 for full access
    command: bundle exec rails server -b
    #Always start the container
    tty: true
    #Launch input interface docker run-synonymous with it of it
    stdin_open: true
    #Backend is cache, temp, log,Mount on git
      - ./backend:/app:cached
      - bundle_data:/usr/local/bundle:cached
      - /app/vendor
      - /app/tmp
      - /app/log
      - /app/.git
      TZ: Asia/Tokyo
    #Control startup order,After db
      - db
      - 5000:3000 #Port forwarding
        ipv4_address: ''

#Set up your own network
  #app_Define a network space called net
    driver: bridge #bridge Connect to network
    ipam: #IP settings
      driver: default
        - subnet: #Define Subnet

#Define two volumes


source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }

ruby '2.6.6'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '~> 6.0.3'
# Use mysql as the database for Active Record
gem 'mysql2', '>= 0.4.4'
# Use Puma as the app server
gem 'puma', '~> 4.1'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
# gem 'jbuilder', '~> 2.7'
# Use Redis adapter to run Action Cable in production
# gem 'redis', '~> 4.0'
# Use Active Model has_secure_password
# gem 'bcrypt', '~> 3.1.7'

# Use Active Storage variant
# gem 'image_processing', '~> 1.2'

# Reduces boot times through caching; required in config/boot.rb
gem 'bootsnap', '>= 1.4.2', require: false

# Use Rack CORS for handling Cross-Origin Resource Sharing (CORS), making cross-origin AJAX possible
# gem 'rack-cors'

group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]

group :development do
  gem 'listen', '~> 3.2'
  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'
  gem 'spring-watcher-listen', '~> 2.0.0'

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

That's why, but there is a gem that is missing ...? I'm doing bundle install ... This came out when I did docker-compose build.

Fetching mysql2 0.5.3
Installing mysql2 0.5.3 with native extensions

The method that could not be solved

NG1: I will add magic words and stuff

Add the following before RUN bundle install in the Dockerfile. Magic word: bundle config --local build.mysql2" --with-ldflags = -L / usr / local / opt / openssl / lib "\ It was no good. .. ..

NG2: Try clearing the cache

After building with docker-compose build --no-cache, I did docker-compose up, It was no good. ..

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