docker with ansible等待数据库

Question

我尝试用ansible部署docker。我有一个docker数据库容器，而在其他容器中是我的web应用程序，我尝试链接这两个容器。问题是数据库容器没有时间自行配置，并且Web容器已经启动。我的ansible剧本看起来像：

...
- name: run mysql in docker container
  docker:
    image: "mysql:5.5"
    name: database
    env: "MYSQL_ROOT_PASSWORD=password"
    state: running

- name: run application containers
  docker:
    name: "application"
    image: "myapp"
    ports:
      - "8080:8080"
    links:
      - "database:db"
    state: running

如何确定数据库是否启动？我尝试使用wait_for模块，但这不起作用。我不想设置超时，这对我来说不是一个好选择。

Answer 1

wait_for不适用于MySQL docker容器，因为它只检查端口是否可连接（对于Docker容器来说这是真的）。但是，wait_for不检查容器内的服务是否侦听端口并将响应发送到客户端。

这就是我在ansible playbook中等待MySQL服务在Docker容器内完全运行的方式：

- name: Start MySQL container
  docker:
    name: some-name
    image: mysql:latest
    state: started
    ports:
    - "8306:3306" # it's important to expose the port for waiting requests
    env:
        MYSQL_ROOT_PASSWORD: "{{ mysql_root_password }}"

- template: mode="a+rx,o=rwx" src=telnet.sh.j2 dest=/home/ubuntu/telnet.sh

# wait while MySQL is starting
- action: shell /home/ubuntu/telnet.sh
  register: result
  until: result.stdout.find("mysql_native_password") != -1
  retries: 10
  delay: 3

而telnet.sh.j2是

#!/bin/bash -e

telnet localhost 8306 || true

Answer 2

为了避免sh和我通常没有安装telnet ...

- name: Wait for database to be available
  shell: docker run --rm --link mysql:mysql mysql sh -c 'mysql -h"$MYSQL_PORT_3306_TCP_ADDR" -P"$MYSQL_PORT_3306_TCP_PORT" -uroot -p{{mysql_password}} || true'
  register: result
  until: result.stderr.find("Can't connect to MySQL") == -1
  retries: 10
  delay: 3

Answer 3

使用wait_for模块。我不是MySQL的专家，但我认为在某些日志文件等中会有一些端口或文件或消息的存在。您可以检查以确定数据库是否已启动。

以下是从上面的链接复制的wait_for示例。

# wait 300 seconds for port 8000 to become open on the host, don't start checking for 10 seconds
- wait_for: port=8000 delay=10

# wait 300 seconds for port 8000 of any IP to close active connections, don't start checking for 10 seconds
- wait_for: host=0.0.0.0 port=8000 delay=10 state=drained

# wait 300 seconds for port 8000 of any IP to close active connections, ignoring connections for specified hosts
- wait_for: host=0.0.0.0 port=8000 state=drained exclude_hosts=10.2.1.2,10.2.1.3

# wait until the file /tmp/foo is present before continuing
- wait_for: path=/tmp/foo

# wait until the string "completed" is in the file /tmp/foo before continuing
- wait_for: path=/tmp/foo search_regex=completed

# wait until the lock file is removed
- wait_for: path=/var/lock/file.lock state=absent

# wait until the process is finished and pid was destroyed
- wait_for: path=/proc/3466/status state=absent

# wait 300 seconds for port 22 to become open and contain "OpenSSH", don't assume the inventory_hostname is resolvable
# and don't start checking for 10 seconds
- local_action: wait_for port=22 host="{{ ansible_ssh_host | default(inventory_hostname) }}" search_regex=OpenSSH delay=10

Answer 4

这对我很有用：

  - name: get mariadb IP address
    command: "docker inspect --format '{''{ .NetworkSettings.IPAddress }''}' mariadb-container"
    register: mariadb_ip_address
  - name: wait for mariadb to become ready
    wait_for:
      host: "{{ mariadb_ip_address.stdout }}"
      port: 3306
      state: started
      delay: 5
      connect_timeout: 15
      timeout: 30

Answer 5

作为etrubenok said：

wait_for不适用于MySQL docker容器，因为它只检查端口是否可连接（对于Docker容器来说这是真的）。但是，wait_for不检查容器内的服务是否侦听端口并将响应发送到客户端。

使用Andy Shinn's suggestion of FreshPow's answer，您可以等待而无需shell脚本或telnet：

- name: Wait for mariadb
  command: >
    docker exec {{ container|quote }}
    mysqladmin ping -u{{ superuser|quote }} -p{{ superuser_password|quote }}
  register: result
  until: not result.rc  # or result.rc == 0 if you prefer
  retries: 20
  delay: 3

这会运行mysqladmin ping ...直到成功（返回代码0）。通常超级用户是root。我使用podman而不是docker进行了测试，但我相信命令是相同的。 |quote做壳逃逸，使用according to the Ansible docs时也应该做command: