[First environment construction] I tried to create a Rails 6 + MySQL 8.0 + Docker environment on Windows 10.

Introduction

I tried to build Rails6 and Docker environment, so I will leave it here as a memorandum. Qiita This is my first post, and since I am a beginner, I think there are various points that cannot be reached, so I would appreciate it if you could point out any mistakes.

environment

• Windows10 Pro
• Ruby2.7.1
• Rails6.0.3.1
• MySQL8.0

reference Build Rails6 + MySQL environment with docker-compose [Rails environment construction] Environment construction with docker + rails + mysql (even beginners can complete in 30 minutes!) [ENTRYPOINT is "must execute", CMD is "(default) argument"](https://pocketstudio.net/2020/01 / 31 / cmd-and-entrypoint /)

It was carried out with reference to this.

goal

Build the environment and display the Rails home screen.

1. Install Docker for Windows

https://hub.docker.com/ Go to and install.

2. Write a Dockerfile

$ mkdir ~/Desktop/docker-tutrial/Rails_app
$ cd  ~/Desktop/docker-tutrial/Rails_app
$ code Dockerfile

Open a terminal, create a directory in any location, and write `` `Dockerfile``` as follows. (I use vsCode.)

$code file name

Then vsCode will start and you can write a new file. (VsCode must be installed on your PC in advance.)

FROM ruby:2.7
RUN apt-get update -qq && apt-get install -y nodejs yarnpkg
RUN ln -s /usr/bin/yarnpkg /usr/bin/yarn
RUN mkdir /app
WORKDIR /app
COPY Gemfile /app/Gemfile
COPY Gemfile.lock /app/Gemfile.lock
RUN bundle install
COPY . /app

# 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

# Start the main process.
CMD ["rails", "server", "-b", "0.0.0.0"]

3. Description of Gemfile

source 'https://rubygems.org'
gem 'rails', '~>6'

$ touch Gemfile.lock

Write the initial `Gemfile` and the empty `` `Gemfile.lock```.

Four. Description of entrypoint.sh

Entrypoint defined as ENTRYPOINT in Dockerfile.Describe sh.

```shell

#!/bin/bash
set -e

# Remove a potentially pre-existing server.pid for Rails.
rm -f /app/tmp/pids/server.pid

# Then exec the container's main process (what's set as CMD in the Dockerfile).
exec "$@"

Five. Description of docker-compose.yml

version: '3'
services:
  db:
    image: mysql:8.0
    volumes:
      - ./tmp/db:/var/lib/mysql
    environment:
      - MYSQL_ALLOW_EMPTY_PASSWORD=1
  web:
    build: .
    command: bash -c "rm -f tmp/pids/server.pid && bundle exec rails s -p 3000 -b '0.0.0.0'"
    volumes:
      - .:/app
    ports:
      - "3000:3000"
    depends_on:
      - db

MySQL uses version 8.0

By setting ** MYSQL_ALLOW_EMPTY_PASSWORD **, you can connect as root even if the password is empty.

6. Rails new and doocker-compose build.

$ docker-compose run web bundle exec rails new . --force --database=mysql

Overwrite the existing file with ** --force ** and specify MySQL with ** --database **. Now that you have the usual Rails fileset, build it.

$ docker-compose build

7. Change the DB host name and do docker-compose up.

Since the database connection cannot be made as it is, Replace the ** host ** part of ** config / database.yml ** with ** db **.

default: &default
  adapter: mysql2
  encoding: utf8mb4
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: root
  password:
  host: db
development:
  <<: *default
  database: app_development
test:
  <<: *default
  database: app_test

** db ** is the container name.

Once this is done, build again and do ** docker-compose up **. If you access Rails with ** localhost: 3000 **, you will get ** ActiveRecord :: NoDatabaseError **.

This happens because the web container does not support the ** caching_sha2_password authentication method ** of mysql 8.0. Follow the steps below to change to the old authentication method ** mysql_native_password **.

8. 8. Change of MySQL authentication method

First of all, enter the DB container and start bash.

$ docker-compose exec db bash

Then connect with the mysql command.

# mysql -u root
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 8.0.18 MySQL Community Server - GPL

...

You can see the user list and its authentication method by sending the following query.

mysql> select User,Host,plugin from mysql.user;
+------------------+-----------+-----------------------+
| User             | Host      | plugin                |
+------------------+-----------+-----------------------+
| root             | %         | caching_sha2_password |
| mysql.infoschema | localhost | caching_sha2_password |
| mysql.session    | localhost | caching_sha2_password |
| mysql.sys        | localhost | caching_sha2_password |
| root             | localhost | caching_sha2_password |
+------------------+-----------+-----------------------+
5 rows in set (0.00 sec)

Change ** caching_sha2_password ** in the rightmost plugin to ** mysql_native_password **. Use ** ALTER USER ** to change the target ** root @% ** user settings this time.

ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY '';
-- Query OK, 0 rows affected (0.02 sec)

After change

mysql> select User,Host,plugin from mysql.user;
+------------------+-----------+-----------------------+
| User             | Host      | plugin                |
+------------------+-----------+-----------------------+
| root             | %         | mysql_native_password |
| mysql.infoschema | localhost | caching_sha2_password |
| mysql.session    | localhost | caching_sha2_password |
| mysql.sys        | localhost | caching_sha2_password |
| root             | localhost | caching_sha2_password |
+------------------+-----------+-----------------------+
5 rows in set (0.00 sec)

9. Access the Rails home screen.

If you do ** db: prepare ** and create a DB, you will be able to access the Rails home screen.