dockerでrailsを立ち上げるとmysqlエラーになる

前提・実現したいこと

https://www.youtube.com/watch?v=lZD1MIHwMBY&t=10100s
上記の動画の１時間36分以降から「Docker ComposeでRailsを構築しよう」を見て、
rails環境をdockerで作っています。

その際に、
https://github.com/takoyan33/docker-youtube2/tree/7c38b18ff957958aa18bb1a58dc2f50480c8ad6d
のコードの状態（second-comitt）の状態で、

$ docker-compose run web rails new . --force --database=mysql
$ ocker-compose run web bundle install (bundleエラーが出たため）
$ docker-compose build

をしました。
その後、

docker-compose run web bundle exec rake db:create

を起動したんですが、以下のエラーが発生しました。

Creating docker-youtube2_web_run ... done
Can't connect to local MySQL server through socket '/run/mysqld/mysqld.sock' (2)
Couldn't create 'app_development' database. Please check your configuration.
rake aborted!
Mysql2::Error::ConnectionError: Can't connect to local MySQL server through socket '/run/mysqld/mysqld.sock' (2)
/usr/local/bundle/gems/mysql2-0.5.3/lib/mysql2/client.rb:90:in `connect'
/usr/local/bundle/gems/mysql2-0.5.3/lib/mysql2/client.rb:90:in `initialize'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `new'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `mysql2_connection'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:830:in `new_connection'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:874:in `checkout_new_connection'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:853:in `try_to_checkout_new_connection'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:814:in `acquire_connection'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:538:in `checkout'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:382:in `connection'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:1033:in `retrieve_connection'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_handling.rb:118:in `retrieve_connection'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/connection_handling.rb:90:in `connection'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/mysql_database_tasks.rb:6:in `connection'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/mysql_database_tasks.rb:14:in `create'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:119:in `create'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:139:in `block in create_current'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:316:in `block in each_current_configuration'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:313:in `each'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:313:in `each_current_configuration'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/tasks/database_tasks.rb:138:in `create_current'
/usr/local/bundle/gems/activerecord-5.2.6/lib/active_record/railties/databases.rake:29:in `block (2 levels) in <main>'
/usr/local/bundle/gems/rake-13.0.6/exe/rake:27:in `<top (required)>'
/usr/local/bin/bundle:23:in `load'
/usr/local/bin/bundle:23:in `<main>'
Tasks: TOP => db:create
(See full trace by running task with --trace)
ERROR: 1

mysqlのエラーというのは分かったのですが、その先から進めず解決法がわかる方がいれば教えて頂きたいです。

#docker-compose up -d  した時のローカルホストの画面

Mysql2::Error::ConnectionError
Can't connect to local MySQL server through socket '/run/mysqld/mysqld.sock' (2)
Extracted source (around line #90):

      conn_attrs = parse_connect_attrs(opts[:connect_attrs])

      connect user, pass, host, port, database, socket, flags, conn_attrs
    end

    def parse_ssl_mode(mode)

Rails.root: /app

Application Trace | Framework Trace | Full Trace