docker-compose - networks - /etc/hosts is not updated - docker

Question

I am using Docker version 1.12.3 and docker-compose version 1.8.1. I have some services which contains for example elasticsearch, rabbitmq and a webapp
My problem is that a service can not access another service by its host becuase docker-compose does not put all service hots in /etc/hosts file. I don't know their IP's because it is defined on docker-compose up phase.
I use networks feature as it is described at https://docs.docker.com/compose/networking/ instead of links because I do circular reference and links doesn't support it. But using networks does not put all services hosts to each service nodes /etc/hosts file. I set container_name, I set hostname but nothing happened. What I am missing;
Here is my docker-compose.yml;
version: '2'
services:
elasticsearch1:
image: elasticsearch:5.0
container_name: "elasticsearch1"
hostname: "elasticsearch1"
command: "elasticsearch -E cluster.name=GameOfThrones -E node.name='Ned Stark' -E discovery.zen.ping.unicast.hosts=elasticsearch1,elasticsearch2,elasticsearch3"
volumes:
- "/opt/elasticsearch/data"
ports:
- "9200:9200"
- "9300:9300"
networks:
- webapp
elasticsearch2:
image: elasticsearch:5.0
container_name: "elasticsearch2"
hostname: "elasticsearch2"
command: "elasticsearch -E cluster.name=GameOfThrones -E node.name='Daenerys Targaryen' -E discovery.zen.ping.unicast.hosts=elasticsearch1,elasticsearch2,elasticsearch3"
volumes:
- "/opt/elasticsearch/data"
networks:
- webapp
elasticsearch3:
image: elasticsearch:5.0
container_name: "elasticsearch3"
hostname: "elasticsearch3"
command: "elasticsearch -E cluster.name=GameOfThrones -E node.name='John Snow' -E discovery.zen.ping.unicast.hosts=elasticsearch1,elasticsearch2,elasticsearch3"
volumes:
- "/opt/elasticsearch/data"
networks:
- webapp
rabbit1:
image: harbur/rabbitmq-cluster
container_name: "rabbit1"
hostname: "rabbit1"
environment:
- ERLANG_COOKIE=abcdefg
networks:
- webapp
rabbit2:
image: harbur/rabbitmq-cluster
container_name: "rabbit2"
hostname: "rabbit2"
environment:
- ERLANG_COOKIE=abcdefg
- CLUSTER_WITH=rabbit1
- ENABLE_RAM=true
networks:
- webapp
rabbit3:
image: harbur/rabbitmq-cluster
container_name: "rabbit3"
hostname: "rabbit3"
environment:
- ERLANG_COOKIE=abcdefg
- CLUSTER_WITH=rabbit1
networks:
- webapp
my_webapp:
image: my_webapp:0.2.0
container_name: "my_webapp"
hostname: "my_webapp"
command: "supervisord -c /etc/supervisor/supervisord.conf -n"
environment:
- DYNACONF_SETTINGS=settings.prod
ports:
- "8000:8000"
tty: true
networks:
- webapp
networks:
webapp:
driver: bridge
This is how I understand they can't comunicate with each other;
I get this error on elasticserach cluster initialization;
Caused by: java.net.UnknownHostException: elasticsearch3
And this is how I docker-composing
docker-compose up

Answer 1

If the container expects the hostname to be available immediate when the container starts that is likely why it's failing.
The hostname isn't going to exist until the other containers start. You can use an entrypoint script to wait until all the hostnames are available, then exec elasticsearch ...