docker-composeを使ってrailsとmysqlの接続ができない。

docker-composeを使って、Ruby on Railsのアプリケーションを作ろうとしています。

各種version

Ruby　2.6.3
rails 5.2.3
Mysql 8.0.12

$ docker ps

をやると、mysqlのコンテナと、railsのコンテナが起動しているのが確認できます。
ここからローカルで

$ docker-compose run --rm rails rails db:create

を実行すると、以下のようなエラーが出ます。

Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2 "No such file or directory")
Couldn't create 'app_development' database. Please check your configuration.
rails aborted!
Mysql2::Error::ConnectionError: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2 "No such file or directory")
/usr/local/bundle/gems/mysql2-0.5.2/lib/mysql2/client.rb:90:in `connect'
/usr/local/bundle/gems/mysql2-0.5.2/lib/mysql2/client.rb:90:in `initialize'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `new'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `mysql2_connection'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:811:in `new_connection'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:855:in `checkout_new_connection'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:834:in `try_to_checkout_new_connection'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:795:in `acquire_connection'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:523:in `checkout'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:382:in `connection'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/connection_adapters/abstract/connection_pool.rb:1014:in `retrieve_connection'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/connection_handling.rb:118:in `retrieve_connection'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/connection_handling.rb:90:in `connection'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/tasks/mysql_database_tasks.rb:6:in `connection'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/tasks/mysql_database_tasks.rb:14:in `create'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/tasks/database_tasks.rb:119:in `create'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/tasks/database_tasks.rb:139:in `block in create_current'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/tasks/database_tasks.rb:316:in `block in each_current_configuration'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/tasks/database_tasks.rb:313:in `each'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/tasks/database_tasks.rb:313:in `each_current_configuration'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/tasks/database_tasks.rb:138:in `create_current'
/usr/local/bundle/gems/activerecord-5.2.3/lib/active_record/railties/databases.rake:29:in `block (2 levels) in <main>'
/usr/local/bundle/gems/railties-5.2.3/lib/rails/commands/rake/rake_command.rb:23:in `block in perform'
/usr/local/bundle/gems/railties-5.2.3/lib/rails/commands/rake/rake_command.rb:20:in `perform'
/usr/local/bundle/gems/railties-5.2.3/lib/rails/command.rb:48:in `invoke'
/usr/local/bundle/gems/railties-5.2.3/lib/rails/commands.rb:18:in `<main>'
/usr/local/bundle/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
/usr/local/bundle/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `block in require_with_bootsnap_lfi'
/usr/local/bundle/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
/usr/local/bundle/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require_with_bootsnap_lfi'
/usr/local/bundle/gems/bootsnap-1.4.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
/usr/local/bundle/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
/usr/local/bundle/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
/usr/local/bundle/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
/app/bin/rails:9:in `<top (required)>'
/usr/local/bundle/gems/spring-2.0.2/lib/spring/client/rails.rb:28:in `load'
/usr/local/bundle/gems/spring-2.0.2/lib/spring/client/rails.rb:28:in `call'
/usr/local/bundle/gems/spring-2.0.2/lib/spring/client/command.rb:7:in `call'
/usr/local/bundle/gems/spring-2.0.2/lib/spring/client.rb:30:in `run'
/usr/local/bundle/gems/spring-2.0.2/bin/spring:49:in `<top (required)>'
/usr/local/bundle/gems/spring-2.0.2/lib/spring/binstub.rb:31:in `load'
/usr/local/bundle/gems/spring-2.0.2/lib/spring/binstub.rb:31:in `<top (required)>'
/app/bin/spring:15:in `<top (required)>'
bin/rails:3:in `load'
bin/rails:3:in `<main>'
Tasks: TOP => db:create
(See full trace by running task with --trace)

mysqlコンテナの起動はまちがいなくできているので、mysqlとrailsの接続ができていないと考えているのですが、
どうすればエラーが治るかがわかりません。

教えていただけると幸いです。
よろしくお願いいたします。

Dockerfile
1FROM node:11.10.0 as node
2FROM ruby:2.6.3
3
4ENV LANG C.UTF-8
5
6RUN apt-get update -qq && \
7    apt-get install -y --no-install-recommends \
8    build-essential \
9    libpq-dev \
10    libfontconfig1 && \
11    rm -rf /var/lib/apt/lists/*
12
13ENV ENTRYKIT_VERSION 0.4.0
14
15RUN wget https://github.com/progrium/entrykit/releases/download/v${ENTRYKIT_VERSION}/entrykit_${ENTRYKIT_VERSION}_Linux_x86_64.tgz \
16    && tar -xvzf entrykit_${ENTRYKIT_VERSION}_Linux_x86_64.tgz \
17    && rm entrykit_${ENTRYKIT_VERSION}_Linux_x86_64.tgz \
18    && mv entrykit /bin/entrykit \
19    && chmod +x /bin/entrykit \
20    && entrykit --symlink
21
22ENV YARN_VERSION 1.13.0
23
24COPY --from=node /opt/yarn-v$YARN_VERSION /opt/yarn
25COPY --from=node /usr/local/bin/node /usr/local/bin/
26
27
28RUN ln -s /opt/yarn/bin/yarn /usr/local/bin/yarn \
29    && ln -s /opt/yarn/bin/yarnpkg /usr/local/bin/yarnpkg
30
31RUN mkdir /app
32
33WORKDIR /app
34
35RUN bundle config build.nokogiri --use-system-libraries
36ENTRYPOINT [ \
37    "prehook", "ruby -v", "--", \
38    "prehook", "bundle install -j3 --quiet", "--"]
39

docker
1version: '2'
2services:
3  rails: &app_base
4    build:
5      context: .
6      dockerfile: "Dockerfile.dev"
7    command: ["bundle", "exec", "rails", "s", "-p", "3000", "-b", "0.0.0.0"]
8    env_file:
9      - "./.env.dev"
10    environment:
11      - "WEBPACKER_DEV_SERVER_HOST=webpack"
12    volumes:
13      - ".:/app"
14    volumes_from:
15      - data
16    ports:
17      - "3000:3000"
18    links:
19      - db
20    tty: true
21    stdin_open: true
22  webpack:
23    <<: *app_base
24    command: "bin/webpack-dev-server"
25    environment:
26      - "WEBPACKER_DEV_SERVER_HOST=0.0.0.0"
27    ports:
28      - "3035:3035"
29    depends_on:
30      - rails
31    tty: false
32    stdin_open: false
33  db:
34    image: "mysql"
35    command: "--default-authentication-plugin=mysql_native_password"
36    environment:
37      - "MYSQL_USER=yoshiki"
38      - "MYSQL_PASSWORD=rootroot"
39      - "MYSQL_ROOT_PASSWORD=rootroot"
40    volumes_from:
41      - data
42    ports:
43      - "3306:3306"
44
45  data:
46    image: "busybox"
47    volumes:
48      - "db:/var/run/mysqld/data"
49      - "bundle:/usr/local/bundle"
50
51volumes:
52  db:
53    driver: local
54  bundle:
55    driver: local

config/database.yml
1default: &default
2  adapter: mysql2
3  encoding: utf8
4  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
5  username: <%= ENV.fetch('DATABASE_USER') { 'yoshiki' } %>
6  password: <%= ENV.fetch('DATABASE_PASSWORD') { 'rootroot' } %>
7  host: <%= ENV.fetch('DATABASE_HOST') { 'db' } %>
8  port: <%= ENV.fetch('DATABASE_PORT') { 3306 } %>