如何将主机名添加到同一 docker 网络上的容器？

Question

Suppose I have a docker compose file with two containers. Both reference each other in their /etc/hosts file. Container A has a reference for container B and vice versa. And all of this happens automatically. Now I want to add one or more hostnames to B in A's hosts file. How can I go about doing this? Is there a special way I can achieve this in Docker Compose?

Example:

172.0.10.166 service-b my-custom-hostname

Answer 1

Yes. In your compose file, you can specify network aliases .

services:
  db:
    networks:
      default:
        aliases:
          - database
          - postgres

In this example, the db service could be reached by other containers on the default network using db , database , or postgres .

You can also add aliases to running containers using the docker network connect command with the --alias= option.

Answer 2

Docker compose has an extra_hosts feature that allows additional entries to be added to the container's host file.

Example

docker-compose.yml

web1:
  image: tomcat:8.0
  ports:
    - 8081:8080
  extra_hosts:
    - "somehost:162.242.195.82"
    - "otherhost:50.31.209.229"
web2:
  image: tomcat:8.0
  ports:
    - 8082:8080
web3:
  image: tomcat:8.0
  ports:
    - 8083:8080

Demonstrate host file entries

Run docker compose with the new docker 1.9 networking feature :

$ docker-compose --x-networking up -d
Starting tmp_web1_1
Starting tmp_web2_1
Starting tmp_web3_1

and look at the hosts file in the first container. Shows the other containers, plus the additional custom entries:

$ docker exec tmp_web1_1 cat /etc/hosts 
..
172.18.0.4  web1
172.18.0.2  tmp_web2_1
172.18.0.3  tmp_web3_1
50.31.209.229   otherhost
162.242.195.82  somehost

Answer 3

If I understand your question correctly, you can pass a host name referenced in your host's /etc/hosts file via --add-host flag :

$ docker run ... --add-host="droid" 

Your host's /etc/hosts would need the following entry: xx.xx.xx.xx droid

Of course, xx.xx.xx.xx will need to be reachable from inside the container you just started using the 'docker run' command. You can have one or more --add-host="xyz".

More details about --add-host here:

http://docs.docker.com/v1.8/reference/commandline/run/