About operating environment

--Edition Windows 10 Home

version 20H2 --OS build 19042.685 --Linux distribution Ubuntu LTS 20.04.1

About Docker Desktop

WSL2 must be installed before installing Docker Desktop.

If you have not installed WSL2, you can refer to the here document.

Install Docker Desktop from the official website below. https://www.docker.com/products/docker-desktop

After the installation is complete, launch Docker Desktop and click the Settings button in the upper right corner. Make sure that General Use the WSL 2 based engine (Windows Home can only run the WSL 2 backend is checked. Then open WSL INTEGRATION in Resources, check the installed WSL2 distribution (Ubuntu-20.04 in my case) and press Apply & Restart.

Reference: https://docs.microsoft.com/ja-jp/windows/wsl/tutorials/wsl-containers

About Rails environment construction

usage environment

rails 5.2.4.4
ruby 2.7.2
MySQL 5.7.32

Flow from rails new to executing rails s

In the conventional environment, executing the rails new command creates a new directory, but in the case of Docker, you need to create the directory manually in advance. For example, if you type the command rails new sample_app, the sample_app directory will be created, but in the case of Docker, you need to create the sample_app directory first, and the work from now on will be done under the directory created in advance. I will.

File preparation

Create four files, Dockerfile, Gemfile, Gemfile.lock, and docker-compose.yml, in any directory you created in advance. Dockerfile

`Dockerfile`


FROM ruby:2.7.2
RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs
RUN curl -sL https://deb.nodesource.com/setup_10.x | bash - \
   && apt-get install -y nodejs
RUN mkdir /myapp
WORKDIR /myapp
ADD Gemfile /myapp/Gemfile
ADD Gemfile.lock /myapp/Gemfile.lock
RUN bundle install
ADD . /myapp

Simply put, the Dockerfile is for fetching Docker images. The Docker image is necessary when creating a Docker container, and the virtual environment is executed based on this. The FROM command is for fetching the required image and should be written at the beginning of the Dockerfile. The RUN command is for executing commands. Set the working directory in the container to myapp with WORKDIR/myapp. With ADD Gemfile/myapp/Gemfile, copy the local Gemfile to myapp/Gemfile in the container.

Gemfile

`Gemfile`


source 'https://rubygems.org'
gem 'rails', '5.2.4.4'

Gemfile.lock Create an empty file with the name Gemfile.lock.

docker-compose.yml

`docker-compose.yml`


version: '3'
services:
  db:
    image: mysql:5.7.32
    environment:
      MYSQL_USER: root
      MYSQL_ROOT_PASSWORD: password
    ports:
      - '3306:3306'
    volumes:
      - ./db/mysql/volumes:/var/lib/mysql

  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

This is also briefly explained. docker-compose is a tool for managing multiple containers. This time, we will launch two containers, db (mysql) and web (rails). You can run a container based on this file and set up a virtual environment by executing the docker-compose command only once.

version is the version of docker-compose. You can check the current latest version from the following site. https://docs.docker.com/compose/compose-file/

services is a description required when defining each element (db and web in this case) required to run the application as service. volumes is a description for synchronizing the local (host) and container. ports is for accessing the web server in the container, and this time it is described as" 3000: 3000 ", but this corresponds to port 3000 in the container and port 3000 in the host. It is attached.

Command execution

After creating Dockerfile, Gemfile, Gemfile.lock, docker-compose.yml, change to the directory where you created these files and execute the following command at the command prompt. At that time, you can run it locally without entering the wsl environment.

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

Running this command will create a lot of folders and files. Maybe I get an error with nokogiri related installation, but in my case it was solved by restarting the PC.

Modify config/database.yml

`config/database.Partial excerpt from yml`


default: &default
  adapter: mysql2
  encoding: utf8
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: root
  password: password
  host: db

Modify password: and host: to the contents described in docker-compose.yml. Then execute the following command.

Command to execute when modifying a local file

docker-compose build

Launch rails server

First, run the following command to create the database.

docker-compose run web rails db:create

Then run the command below.

docker-compose up

Executing this command will start the container as described in docker-compose.yml.

If you access http: // localhost: 3000 /, you will see the usual screen.

In future Rails development using Docker, add docker-compose run web before the rails command.

docker-compose run web rails

I will execute the command like this.

At the end

Since WSL2 can be used as a backend for Docker Desktop for Windows, it has become possible to easily build a Docker environment, so I introduced Docker, which I had been interested in for a long time. I used to develop rails with vagrant, but since I introduced Docker, development has become convenient.

Reference material

https://www.ccs1981.jp/blog/wsl2%E3%81%A8docker%E3%81%A7%E9%96%8B%E7%99%BA%E7%92%B0%E5%A2%83%E3%82%92%E4%BD%9C%E3%82%8B/ http://docs.docker.jp/v17.06/engine/reference/builder.html https://qiita.com/yuta-ushijima/items/d3d98177e1b28f736f04

A memo when building a Rails 5.2 development environment using Docker Desktop + WSL2 on Windows 10 Home