How do I set hostname in docker-compose?

Question

In my docker-compose.yml file, I have the following. However the container does not pick up the hostname value. Any ideas?

dns:
  image: phensle         


        

Answer 1

For docker compose version: "3.4"

It works for me:

services:
    my-service:
        hostname: my_host_name

Don't need to use dns. Just use hostname. Compose file version 3 reference

Answer 2

This seems to work correctly. If I put your config into a file:

$ cat > compose.yml <<EOF
dns:
  image: phensley/docker-dns
  hostname: affy
  domainname: affy.com
  volumes:
    - /var/run/docker.sock:/docker.sock
EOF

And then bring things up:

$ docker-compose -f compose.yml up
Creating tmp_dns_1...
Attaching to tmp_dns_1
dns_1 | 2015-04-28T17:47:45.423387 [dockerdns] table.add tmp_dns_1.docker -> 172.17.0.5

And then check the hostname inside the container, everything seems to be fine:

$ docker exec -it stack_dns_1 hostname
affy.affy.com

Answer 3

The simplest way I have found is to just set the container name in the docker-compose.yml See container_name documentation. It is applicable to docker-compose v1+. It works for container to container, not from the host machine to container.

services:
  dns:
    image: phensley/docker-dns
    container_name: affy

Now you should be able to access affy from other containers using the container name. I had to do this for multiple redis servers in a development environment.

NOTE The solution works so long as you don't need to scale. Such as consistant individual developer environments.

Answer 4

I needed to spin freeipa container to have a working kdc and had to give it a hostname otherwise it wouldn't run. What eventually did work for me is setting the HOSTNAME env variable in compose:

version: 2
services:
  freeipa:
    environment:
      - HOSTNAME=ipa.example.test

Now its working:

docker exec -it freeipa_freeipa_1 hostname
ipa.example.test

Answer 5

I found that the hostname was not visible to other containers when using docker run. This turns out to be a known issue (perhaps more a known feature), with part of the discussion being:

We should probably add a warning to the docs about using hostname. I think it is rarely useful.

The correct way of assigning a hostname - in terms of container networking - is to define an alias like so:

services:
  some-service:
    networks:
      some-network:
        aliases:
          - alias1
          - alias2

Unfortunately this still doesn't work with docker run. The workaround is to assign the container a name:

docker-compose run --name alias1 some-service

And alias1 can then be pinged from the other containers.

UPDATE: As @grilix points out, you should use docker-compose run --use-aliases to make the defined aliases available.

Answer 6

As of docker-compose version 3 and later, you can just use the hostname key:

version: '3'
services:
  dns:
    hostname: 'your-name'