networking - Docker container is unable to connect to port opened by another docker container -

i have 2 containers running: c1 , c2.

c1 listening on port 2181 , c2 connecting port 2181

problem c2 fails connect c1 on said port , i'm not sure why.

when run code connects c1 not in container works fine. know c1 running , port exposed correctly. when drop application in it's own container port not visible anymore.

i've tried lsof within c2 , not listed, makes sense why fails.

any clues on need next appreciated.

i using docker-compose containers should in same network group default:

here's compose file:

version: '2' services:   c1:     build: .     volumes:       - .:/code     depends_on:       - c2   c2:     image: jplock/zookeeper     ports:        - "2181:2181"        - "2888:2888"        - "3888:3888" 

in c1, initiator using uri localhost:2181

if come across post might help.

using docker-compose, containers set hostname matching service alias in docker compose file, see docs here:

https://docs.docker.com/compose/networking/

modified quote fit use-case

each container can hostname (i.e c2) , appropriate container’s ip address. example, c1 application code connect url //c2:2181.