在 docker compose 上运行时无法连接到 rails 应用程序中的数据库

Question

我是 DevOps 领域的新手，我正在 docker-compose 上运行一个简单的 rails 应用程序。当我在 config.yml 应用程序中硬编码 DB 凭据时工作正常，但是当我引用 docker-compose.yaml 中声明的 ENV 变量时，我的应用程序容器没有与 DB 建立连接。

下面是我的 config.yaml

default: &default
  adapter: mysql2
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  database: <%= ENV['DB_DATABASE']%>
  host: <%= ENV['DB_HOST'] %>
  user: <%= ENV['DB_USERNAME'] %>
  password: <%= ['DB_PASSWORD'] %>
  timeout: 5000
  socket: /var/run/mysqld/mysqld.sock

development:
  <<: *default
  host: <%= ENV['DB_HOST'] %>
  user: <%= ENV['DB_USERNAME'] %>
  password: <%= ['DB_PASSWORD'] %>
  socket: /var/run/mysqld/mysqld.sock
  database: <%= ENV['DB_DATABASE']%>


production:
  <<: *default
  database: <%= ENV['DB_DATABASE']%>
  host: <%= ENV['DB_HOST'] %>
  user: <%= ENV['DB_USERNAME'] %>
  password: <%= ENV['DB_PASSWORD'] %>
  socket: /var/run/mysqld/mysqld.sock

下面是我的 docker-compose.yaml 文件。

version: '3'
services:
  webapp:
    build: .
    command: bash -c "bundle exec rails s -p 3001 -b '0.0.0.0'"
    ports:
      - '3001:3001'
    volumes:
      - '.:/data/checklist'
    depends_on:
      - db
    environment:
      DB_USERNAME: "root"
      DB_PASSWORD: "Mission2019"
      DB_DATABASE: "list"
      DB_PORT: 3306
      DB_HOST: db
      RAILS_ENV: production
      RAILS_MAX_THREADS: 5  
  db:
    image: mysql:5.7
    restart: always
    environment:
      MYSQL_DATABASE: "list"
      MYSQL_ROOT_PASSWORD: "Mission2019"
      MYSQL_USERNAME: "root"
      MYSQL_PASSWORD: "Mission2019"
    ports:
      - '3307:3306'
    expose:
      - '3306'

我得到以下错误

webapp_1  | ============= END WARNING FROM mysql2 =========
db_1      | 2020-07-21T07:44:59.886096Z 2 [Note] Access denied for user 'root'@'172.21.0.3' (using password: YES)
webapp_1  | I, [2020-07-21T07:44:59.887550 #1]  INFO -- : [e78ce127-bb02-45f2-be3a-91b05e564b4b] Completed 500 Internal Server Error in 40ms
webapp_1  | F, [2020-07-21T07:44:59.889463 #1] FATAL -- : [e78ce127-bb02-45f2-be3a-91b05e564b4b]   
webapp_1  | F, [2020-07-21T07:44:59.889559 #1] FATAL -- : [e78ce127-bb02-45f2-be3a-91b05e564b4b] Mysql2::Error (Access denied for user 'root'@'172.21.0.3' (using password: YES)):
webapp_1  | F, [2020-07-21T07:44:59.889600 #1] FATAL -- : [e78ce127-bb02-45f2-be3a-91b05e564b4b]   
webapp_1  | F, [2020-07-21T07:44:59.889658 #1] FATAL -- : [e78ce127-bb02-45f2-be3a-91b05e564b4b] mysql2 (0.4.10) lib/mysql2/client.rb:89:in `connect'
webapp_1  | [e78ce127-bb02-45f2-be3a-91b05e564b4b] mysql2 (0.4.10) lib/mysql2/client.rb:89:in `initialize'
webapp_1  | [e78ce127-bb02-45f2-be3a-91b05e564b4b] activerecord (5.2.4.3) lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `new'
webapp_1  | [e78ce127-bb02-45f2-be3a-91b05e564b4b] activerecord (5.2.4.3) lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `mysql2_connection'
webapp_1  | [e78ce127-bb02-45f2-be3a-91b05e564b4b] activerecord (5.2.4.3) lib/active_record/connection_adapters/abstract/connection_pool.rb:830:in `new_connection'
webapp_1  | [e78ce127-bb02-45f2-be3a-91b05e564b4b] activerecord (5.2.4.3) lib/active_record/connection_adapters/abstract/connection_pool.rb:874:in `checkout_new_connection'
webapp_1  | [e78ce127-bb02-45f2-be3a-91b05e564b4b] activerecord (5.2.4.3) lib/active_record/connection_adapters/abstract/connection_pool.rb:853:in `try_to_checkout_new_connection'

Answer 1

首先，您将 database.yml 文件引用到 config.yml。您无需创建自定义配置文件，而是可以使用 database.yml。

错误消息说明数据库可访问但密码不正确。这可能是由于“密码：”行的 config.yml (database.yml) 中的拼写错误，但这应该是“密码： " 默认为开发环境。请在生产环境中也进行相同的验证。

我对你的文件进行了修改，它适用于所有环境。文件如下。

更新database.yml文件：

default: &default
  adapter: mysql2
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  database: <%= ENV['DB_DATABASE']%>
  host: <%= ENV['DB_HOST'] %>
  port: <%= ENV["DB_PORT"] %>
  user: <%= ENV['DB_USERNAME'] %>
  password: <%= ENV['DB_PASSWORD'] %>
  timeout: 5000
  socket: /var/run/mysqld/mysqld.sock

development:
  <<: *default


production:
  <<: *default

更新的 docker-compose.yml 文件：

version: '3'
services:
  webapp:
    build: .
    command: bash -c "bundle exec rake db:migrate && bundle exec rails s -p 3001 -b '0.0.0.0'"
    ports:
      - '3001:3001'
    volumes:
      - '.:/data/checklist'
    depends_on:
      - db
    environment:
      DB_USERNAME: "root"
      DB_PASSWORD: "Mission2019"
      DB_DATABASE: "list"
      DB_PORT: 3306
      DB_HOST: db
      RAILS_ENV: production 
      RAILS_MAX_THREADS: 5  
    volumes:
      - .:/code
  db:
    image: mysql:5.7
    restart: always
    environment:
      MYSQL_DATABASE: "list"
      MYSQL_ROOT_PASSWORD: "Mission2019"
      MYSQL_USERNAME: "root"
      MYSQL_PASSWORD: "Mission2019"

如果您不从主机访问数据库，则不需要“docker-compose.yml”中的端口和公开密钥。通常端口的值应该是“3306:3306”，除非您不会从主机的不同端口访问数据库。