docker - 在docker-compose中创建一个全局变量od “extra_hosts”

Question

假设我在docker-compose中有十个服务，每个此服务都需要具有四个记录的相同extra_hosts。
我想一次定义extra_hosts，并且只将其包括在每个服务中。

可能吗？

version: '3.7'
services:

  web:
    build:
      context: ./apache
      dockerfile: dockerfile_apache2
    image: debian:latest
    container_name: hsthttp1
    extra_hosts:
     - "somehost1:162.242.195.82"
     - "somehost2:162.242.195.83"
     - "somehost3:162.242.195.84"
     - "somehost4:162.242.195.85"
  web2:
    build:
      context: ./apache
      dockerfile: dockerfile_apache2
    image: debian:latest
    container_name: hsthttp2
    extra_hosts:
     - "somehost1:162.242.195.82"
     - "somehost2:162.242.195.83"
     - "somehost3:162.242.195.84"
     - "somehost4:162.242.195.85"
  web3:
    build:
      context: ./apache
      dockerfile: dockerfile_apache2
    image: debian:latest
    container_name: hsthttp3
    extra_hosts:
     - "somehost1:162.242.195.82"
     - "somehost2:162.242.195.83"
     - "somehost3:162.242.195.84"
     - "somehost4:162.242.195.85"

Answer 1

是的，自从撰写3.4版以来，就可以使用Extension fields定义可重用的片段:

根据您的情况，可以使用next:

docker-compose.yaml:

version: '3.7'

x-extra_hosts:
  &default-extra_hosts
  - "somehost1:162.242.195.82"
  - "somehost2:162.242.195.83"
  - "somehost3:162.242.195.84"
  - "somehost4:162.242.195.85"

services:
  web:
    image: debian:latest
    container_name: hsthttp1
    extra_hosts: *default-extra_hosts
  web2:
    image: debian:latest
    container_name: hsthttp2
    extra_hosts: *default-extra_hosts
  web3:
    image: debian:latest
    container_name: hsthttp3
    extra_hosts: *default-extra_hosts

上面，我们定义了一个全局&default-extra_hosts，稍后在每个服务中，我们都可以使用*default-extra_hosts引用它。

您可以使用docker-compose config快速检查效果，如下所示:

shubuntu1@shubuntu1:~/try$ docker-compose config
services:
  web:
    container_name: hsthttp1
    extra_hosts:
    - somehost1:162.242.195.82
    - somehost2:162.242.195.83
    - somehost3:162.242.195.84
    - somehost4:162.242.195.85
    image: debian:latest
  web2:
    container_name: hsthttp2
    extra_hosts:
    - somehost1:162.242.195.82
    - somehost2:162.242.195.83
    - somehost3:162.242.195.84
    - somehost4:162.242.195.85
    image: debian:latest
  web3:
    container_name: hsthttp3
    extra_hosts:
    - somehost1:162.242.195.82
    - somehost2:162.242.195.83
    - somehost3:162.242.195.84
    - somehost4:162.242.195.85
    image: debian:latest
version: '3.7'