MySQL 2：：Error：：ConnectionError:无法连接到“mysql”上的mysql服务器(111个“拒绝连接”)

Question

我正在为我的示例应用程序运行docker-组合，这个文件由mysql数据库和应用程序映像组成。我得到了以下错误。

    $ docker logs -f sample-application
    Can't connect to MySQL server on 'mysql' (111 "Connection refused")
    Couldn't create database for {"adapter"=>"mysql2", "encoding"=>"utf8", "pool"=>5, "reconnect"=>true, "database"=>"datagen", "username"=>"root", "password"=>"password", "host"=>"mysql", "port"=>3306}
    rake aborted!
    Mysql2::Error::ConnectionError: Can't connect to MySQL server on 'mysql' (111 "Connection refused")
    /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-5.2.1/lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `new'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/connection_adapters/mysql2_adapter.rb:22:in `mysql2_connection'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:809:in `new_connection'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:853:in `checkout_new_connection'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:832:in `try_to_checkout_new_connection'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:793:in `acquire_connection'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:521:in `checkout'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:380:in `connection'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:1008:in `retrieve_connection'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/connection_handling.rb:118:in `retrieve_connection'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/connection_handling.rb:90:in `connection'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/tasks/mysql_database_tasks.rb:6:in `connection'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/tasks/mysql_database_tasks.rb:14:in `create'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/tasks/database_tasks.rb:119:in `create'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/tasks/database_tasks.rb:139:in `block in create_current'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/tasks/database_tasks.rb:316:in `block in each_current_configuration'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/tasks/database_tasks.rb:313:in `each'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/tasks/database_tasks.rb:313:in `each_current_configuration'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/tasks/database_tasks.rb:138:in `create_current'
    /usr/local/bundle/gems/activerecord-5.2.1/lib/active_record/railties/databases.rake:29:in `block (2 levels) in <top (required)>'
    /usr/local/bundle/gems/rake-12.3.1/exe/rake:27:in `<top (required)>'
    Tasks: TOP => db:create
    (See full trace by running task with --trace)

下面是mysql docker的数据库组件-复合yaml文件

version: '3.1'

services:
sample-service:
    image: service:latest
    hostname: sample-service
    container_name: sample-service
    depends_on:
      - sample-application
    ports:
      - "8080:8080"
    networks:
      - $NETWORK_NAME

mysql:
    image: mysql:5.7
    hostname: mysql
    container_name: mysql
    ports:
      - "3306:3306"
    environment:
      - MYSQL_ROOT_PASSWORD=password
      - MYSQL_DATABASE=foo
      - MYSQL_USER=root
      - MYSQL_PASSWORD=password
    networks:
      - $NETWORK_NAME

sample-application:
    image: sample:latest 
    hostname: mysql
    container_name: sample-application
    depends_on:
      - mysql
    ports:
      - "3000:3000"
    environment:
      - RAILS_ENV=production
      - DATABASE_HOST=mysql
      - DATABASE_USER=root
      - DATABASE_NAME=foo
      - DATABASE_PORT=3306
    networks:
      - $NETWORK_NAME

networks:
  datagen:
    external: true

我能够平mysql从应用程序码头容器图像。连接是成功的，同时我也可以从其他机器访问mysql映像。

因此，mysql映像中没有任何问题，但是在使用运行时，我无法连接到mysql主机。我传递的环境变量也是正确的。

我研究了堆栈溢出中的各种问题，并试图更改绑定地址。但我在mysql容器映像中没有看到它。

    bash-4.2# find / -name "*.cnf"
    /var/lib/mysql/auto.cnf
    /usr/share/mysql/my-default.cnf
    /etc/pki/tls/openssl.cnf
    /etc/my.cnf
    /healthcheck.cnf
    bash-4.2# cat /etc/my.cnf
    # For advice on how to change settings please see
    # http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html

    [mysqld]
    #
    # Remove leading # and set to the amount of RAM for the most important data
    # cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
    # innodb_buffer_pool_size = 128M
    #
    # Remove leading # to turn on a very important data integrity option: logging
    # changes to the binary log between backups.
    # log_bin
    #
    # Remove leading # to set options mainly useful for reporting servers.
    # The server defaults are faster for transactions and fast SELECTs.
    # Adjust sizes as needed, experiment to find the optimal values.
    # join_buffer_size = 128M
    # sort_buffer_size = 2M
    # read_rnd_buffer_size = 2M
    skip-host-cache
    skip-name-resolve
    datadir=/var/lib/mysql
    socket=/var/lib/mysql/mysql.sock
    secure-file-priv=/var/lib/mysql-files
    user=mysql

    # Disabling symbolic-links is recommended to prevent assorted security risks
    symbolic-links=0

    log-error=/var/log/mysqld.log
    pid-file=/var/run/mysqld/mysqld.pid

Answer 1

你真的需要外部网络吗？唯一可能的原因是您希望将其他容器连接到它。否则，不要使用它-您将能够访问容器从主机只是通过端口暴露机制。

如果您不打算从外部docker-compose访问数据库，请考虑对文件进行以下更改：

• 移除无用的东西
• 删除端口(在用户定义的网络中，您不需要公开)

docker-compose.yml

version: '3.1'

services:
  mysql:
    image: mysql:5.7
    environment:
      - MYSQL_ROOT_PASSWORD=password
      - MYSQL_DATABASE=foo
      - MYSQL_USER=root
      - MYSQL_PASSWORD=password

  sample-application:
    image: sample:latest 
    depends_on:
      - mysql
    environment:
      - RAILS_ENV=production
      - DATABASE_HOST=mysql
      - DATABASE_USER=root
      - DATABASE_NAME=foo
      - DATABASE_PORT=3306

  sample-service:
    image: service:latest
    depends_on:
      - sample-application

通过这样的配置，您可以使用网络内部的服务名称访问服务，例如mysql、sample-service和sample-application。

顺便说一句，当服务依赖于应用程序，而不是相反的情况时，情况会很奇怪。

Answer 2

如果您使用rails连接到Mysql，请确保database.yml中的db主机与docker-compose中的服务名称(在本例中为mysql)相同，这就是它如何知道如何连接到mysql容器。删除所有容器和图像，并从一开始就进行构建，以确保没有缓存任何配置。