Mysql2::Error::ConnectionError Unknown MySQL server host 'db' (0) ←これを解決したい

どうしてもわからないので質問させてください。

エラーコードを検索して、一通り試してみたのですが、原因特定には至らず。

流れとしては、　docker（rails）　の環境構築は成功して、一度 rails s をした時は、しっかりと表示されました。

変更点と致しましては、次の日に、　rails generate controller StaticPages home help　を実行し、新しくコントローラーを作成した時に、 bundle のバージョンが違うとのエラーがでて、 gemfile.lock を少し触ったくらいです。

この変更をした後に、rails s　したところでエラーに気がつきました。

ターミナル１

docker
1Starting nouhin_app_db_1 ... done
2Starting nouhin_app_web_1 ... done
3Attaching to nouhin_app_db_1, nouhin_app_web_1
4db_1   | 2020-07-31 12:46:40+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 5.7.31-1debian10 started.
5db_1   | 2020-07-31 12:46:40+00:00 [Note] [Entrypoint]: Switching to dedicated user 'mysql'
6db_1   | 2020-07-31 12:46:40+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 5.7.31-1debian10 started.
7db_1   | 2020-07-31T12:46:40.998604Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
8db_1   | 2020-07-31T12:46:40.999970Z 0 [Note] mysqld (mysqld 5.7.31) starting as process 1 ...
9db_1   | 2020-07-31T12:46:41.003157Z 0 [Note] InnoDB: PUNCH HOLE support available
10db_1   | 2020-07-31T12:46:41.003213Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
11db_1   | 2020-07-31T12:46:41.003233Z 0 [Note] InnoDB: Uses event mutexes
12db_1   | 2020-07-31T12:46:41.003243Z 0 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
13db_1   | 2020-07-31T12:46:41.003251Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.11
14db_1   | 2020-07-31T12:46:41.003259Z 0 [Note] InnoDB: Using Linux native AIO
15db_1   | 2020-07-31T12:46:41.003598Z 0 [Note] InnoDB: Number of pools: 1
16db_1   | 2020-07-31T12:46:41.003765Z 0 [Note] InnoDB: Using CPU crc32 instructions
17db_1   | 2020-07-31T12:46:41.006064Z 0 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
18db_1   | 2020-07-31T12:46:41.015164Z 0 [Note] InnoDB: Completed initialization of buffer pool
19db_1   | 2020-07-31T12:46:41.018020Z 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
20db_1   | 2020-07-31T12:46:41.030979Z 0 [Note] InnoDB: Highest supported file format is Barracuda.
21db_1   | 2020-07-31T12:46:41.042335Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables
22db_1   | 2020-07-31T12:46:41.042427Z 0 [Note] InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
23db_1   | 2020-07-31T12:46:41.057836Z 0 [Note] InnoDB: File './ibtmp1' size is now 12 MB.
24db_1   | 2020-07-31T12:46:41.058785Z 0 [Note] InnoDB: 96 redo rollback segment(s) found. 96 redo rollback segment(s) are active.
25db_1   | 2020-07-31T12:46:41.058821Z 0 [Note] InnoDB: 32 non-redo rollback segment(s) are active.
26db_1   | 2020-07-31T12:46:41.059273Z 0 [Note] InnoDB: Waiting for purge to start
27db_1   | 2020-07-31T12:46:41.109709Z 0 [Note] InnoDB: 5.7.31 started; log sequence number 12578102
28db_1   | 2020-07-31T12:46:41.110122Z 0 [Note] Plugin 'FEDERATED' is disabled.
29db_1   | 2020-07-31T12:46:41.110559Z 0 [Note] InnoDB: Loading buffer pool(s) from /var/lib/mysql/ib_buffer_pool
30db_1   | 2020-07-31T12:46:41.114371Z 0 [Note] InnoDB: Buffer pool(s) load completed at 200731 12:46:41
31db_1   | 2020-07-31T12:46:41.117648Z 0 [Note] Found ca.pem, server-cert.pem and server-key.pem in data directory. Trying to enable SSL support using them.
32db_1   | 2020-07-31T12:46:41.117693Z 0 [Note] Skipping generation of SSL certificates as certificate files are present in data directory.
33db_1   | 2020-07-31T12:46:41.118446Z 0 [Warning] CA certificate ca.pem is self signed.
34db_1   | 2020-07-31T12:46:41.118496Z 0 [Note] Skipping generation of RSA key pair as key files are present in data directory.
35db_1   | 2020-07-31T12:46:41.118975Z 0 [Note] Server hostname (bind-address): '*'; port: 3306
36db_1   | 2020-07-31T12:46:41.119178Z 0 [Note] IPv6 is available.
37db_1   | 2020-07-31T12:46:41.119212Z 0 [Note]   - '::' resolves to '::';
38db_1   | 2020-07-31T12:46:41.119234Z 0 [Note] Server socket created on IP: '::'.
39db_1   | 2020-07-31T12:46:41.120790Z 0 [Warning] Insecure configuration for --pid-file: Location '/var/run/mysqld' in the path is accessible to all OS users. Consider choosing a different directory.
40db_1   | 2020-07-31T12:46:41.134861Z 0 [Note] Event Scheduler: Loaded 0 events
41db_1   | 2020-07-31T12:46:41.135772Z 0 [Note] mysqld: ready for connections.
42db_1   | Version: '5.7.31'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  MySQL Community Server (GPL)
43web_1  | /usr/local/lib/ruby/site_ruby/2.5.0/bundler/lockfile_parser.rb:108:in `warn_for_outdated_bundler_version': You must use Bundler 2 or greater with this lockfile. (Bundler::LockfileError)
44web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/bundler/lockfile_parser.rb:95:in `initialize'
45web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/bundler/definition.rb:83:in `new'
46web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/bundler/definition.rb:83:in `initialize'
47web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/bundler/dsl.rb:234:in `new'
48web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/bundler/dsl.rb:234:in `to_definition'
49web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/bundler/dsl.rb:13:in `evaluate'
50web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/bundler/definition.rb:34:in `build'
51web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/bundler.rb:135:in `definition'
52web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/bundler.rb:101:in `setup'
53web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/bundler/setup.rb:20:in `<top (required)>'
54web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:130:in `require'
55web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:130:in `rescue in require'
56web_1  | 	from /usr/local/lib/ruby/site_ruby/2.5.0/rubygems/core_ext/kernel_require.rb:34:in `require'
57web_1  | 	from /app_name/config/boot.rb:3:in `<top (required)>'
58web_1  | 	from bin/rails:3:in `require_relative'
59web_1  | 	from bin/rails:3:in `<main>'
60nouhin_app_web_1 exited with code 1
61

ターミナル２

rails
1=> Booting Puma
2=> Rails 5.2.4.3 application starting in development 
3=> Run `rails server -h` for more startup options
4Puma starting in single mode...
5* Version 3.12.6 (ruby 2.5.3-p105), codename: Llamas in Pajamas
6* Min threads: 5, max threads: 5
7* Environment: development
8* Listening on tcp://localhost:3000
9Use Ctrl-C to stop
10Started GET "/" for ::1 at 2020-07-31 21:47:13 +0900
11  
12Mysql2::Error::ConnectionError (Unknown MySQL server host 'db' (0)):
13

database.yml

#
# Install the MySQL driver
#   gem install mysql2
#
# Ensure the MySQL gem is defined in your Gemfile
#   gem 'mysql2'
#
# And be sure to use new-style password hashing:
#   https://dev.mysql.com/doc/refman/5.7/en/password-hashing.html
#
default: &default
  adapter: mysql2
  encoding: utf8
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: root
  password: password
  host: db

development:
  <<: *default
  database: app_name_development

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  <<: *default
  database: app_name_test

# As with config/secrets.yml, you never want to store sensitive information,
# like your database password, in your source code. If your source code is
# ever seen by anyone, they now have access to your database.
#
# Instead, provide the password as a unix environment variable when you boot
# the app. Read http://guides.rubyonrails.org/configuring.html#configuring-a-database
# for a full rundown on how to provide these environment variables in a
# production deployment.
#
# On Heroku and other platform providers, you may have a full connection URL
# available as an environment variable. For example:
#
#   DATABASE_URL="mysql2://myuser:mypass@localhost/somedatabase"
#
# You can use this database configuration with:
#
#   production:
#     url: <%= ENV['DATABASE_URL'] %>
#
production:
  <<: *default
  database: app_name_production
  username: app_name
  password: <%= ENV['APP_NAME_DATABASE_PASSWORD'] %>

docker-compose.yml

version:
1services:
2  db:
3    image: mysql:5.7
4    environment:
5      MYSQL_ROOT_PASSWORD: password
6      MYSQL_DATABASE: root
7    ports:
8      - "3306:3306"
9
10  web:
11    build: .
12    command: rails s -p 3000 -b '0.0.0.0'
13    volumes:
14      - .:/app_name
15    ports:
16      - "3000:3000"
17    links:
18      - db

長々と失礼致しました。

些細なことでもヒントを頂けると、嬉しいです

行動規範の内容に同意します

回答1件

ベストアンサー

console
1web_1  | /usr/local/lib/ruby/site_ruby/2.5.0/bundler/lockfile_parser.rb:108:in `warn_for_outdated_bundler_version': You must use Bundler 2 or greater with this lockfile. (Bundler::LockfileError)

上記の箇所がエラーの原因のように見えます

次のようにすると良いようです
You must use Bundler 2 or greater with this lockfile. (Bundler::LockfileError) · Issue #7463 · jekyll/jekyll

update Rubygems
gem update --system

update bundler
gem install bundler

update Gemfile.lock in your project
bundler update --bundler

しかし、docker-compose.yml からすると、Dockerfile を使っていると思いますので
次のようにする必要がありそうです:

1
gem update --system, gem install bundler を
Dockerfile の中で RUN 命令で指定します

2
手順 1 で編集した Dockerfile からイメージを再ビルドします

3
手順 2 で再ビルドしたイメージからコンテナーを起動し、
コンテナー内で bundler update を実行します

4
手順 3 で更新された Gemfile.lock を使って
イメージを再々ビルドし直します

投稿2020/07/31 15:10