Elixir Mongo TCP connect: unknown POSIX error

docker-compose.yml

version: '3.3'
services:
  db_1:
    image: mongo:3.0
    expose:
      - "27017"
    command: --replSet murmur --storageEngine wiredTiger --noauth
    networks:
      - skynet
    ports:
      #these ports are opened for using mongo client on host machine
      - "37017:27017"
  db_2:
    image: mongo:3.0
    expose:
      - "27017"
    command: --replSet murmur --storageEngine wiredTiger --noauth
    networks:
      - skynet
    ports:
      #these ports are opened for using mongo client on host machine
      - "37117:27017"
  db_backup:
    image: mongo:3.0
    expose:
      - "27017"
    command: --replSet murmur --storageEngine wiredTiger --noauth
    networks:
      - skynet
    ports:
      #these ports are opened for using mongo client on host machine
      - "37217:27017"
networks:
  skynet:

instruction.md

1. Run docker compose to start up all mongo nodes
2. Connect to db_1 node using mongo -p 37017, got to have mongo client installed locally. You could also docker exec.
3. Run mongo-replicaset-instruction.js in the mongo shell, this configure the replica set.
4. Run your docker supplying --networks arguments to join the above network
5. Before running your application on docker on step 4, run echo "1.1.1.1 db_backup" >> /etc/hosts to point it to non existant destination.
6. Run your app in the docker container you started on step 4.
7. All goes well you should see these messages

23:23:31.799 [error] Mongo.Protocol (#PID<0.643.0>) failed to connect: ** (Mongo.Error) tcp connect: unknown POSIX error - :timeout
 
23:23:31.800 [error] GenServer #PID<0.643.0> terminating
** (stop) exited in: :gen_server.call(#PID<0.643.0>, {:checkout, #Reference<0.3803180105.3846438913.42441>, true, 5000}, 5000)
    ** (EXIT) time out
Last message: []
State: Mongo.Protocol

mongo-replicaset-instruction.js

rs.initiate()
rs.add("db_2")
rs.add("db_backup")
conf=rs.conf()
conf.members[2].priority = 0
rs.reconfig(conf)

Did you solve this problem. I am facing the same issue.