Docker compose port mapping

Question

I have a docker-compose yml file as in below  version   2  services    nodejs      build        context          dockerfile  DockerFile     ports        -  4000 4000      links        - redis     expose        -  6379    redis      build        context          dockerfile  Dockerfile-redis   My goal is to forward nodejs-127 0 0 1 port 6379 to the redis host   I can already ping redis from the nodejs machine  but the ports are not mapped   Tried expose options  but no chance either

User · Answer

If you want to bind to the redis port from your nodejs container you will have to expose that port in the redis container:

version: '2'
services:
  nodejs:
    build:
      context: .
      dockerfile: DockerFile
    ports:
      - "4000:4000"
    links:
      - redis

  redis:
    build:
      context: .
      dockerfile: Dockerfile-redis
    expose:
      - "6379"

The expose tag will let you expose ports without publishing them to the host machine, but they will be exposed to the containers networks.

https://docs.docker.com/compose/compose-file/#expose

The ports tag will be mapping the host port with the container port HOST:CONTAINER

https://docs.docker.com/compose/compose-file/#ports

User · Answer

It s important to point out that all of the above solutions map the port to every interface on your machine  This is less than desirable if you have a public IP address  or your machine has an IP on a large network  Your application may be exposed to a much wider audience than you d hoped   redis    build      context      dockerfile  Dockerfile-redis     ports      -  127 0 0 1 3901 3901    127 0 0 1 is the ip address that maps to the hostname localhost on your machine  So now your application is only exposed over that interface and since 127 0 0 1 is only accessible via your machine  you re not exposing your containers to the entire world   The documentation explains this further and can be found here  https   docs docker com compose compose-file  ports    Note  If you re using Docker for mac this will make the container listen on 127 0 0 1 on the Docker for Mac VM and will not be accessible from your localhost  If I recall correctly

User · Answer

If you want to access redis from the host  127 0 0 1   you have to use the ports command   redis    build      context        dockerfile  Dockerfile-redis     ports      -  6379 6379

User · Answer

It seems like the other answers here all misunderstood your question   If I understand correctly  you want to make requests to localhost 6379  the default for redis  and have them be forwarded  automatically  to the same port on your redis container   https   unix stackexchange com a 101906 38639 helped me get to the right answer   First  you ll need to install the nc command on your image   On CentOS  this package is called nmap-ncat  so in the example below  just replace this with the appropriate package if you are using a different OS as your base image   Next  you ll need to tell it to run a certain command each time the container boots up   You can do this using CMD     Add this to your Dockerfile RUN yum install -y --setopt skip missing names on install False nmap-ncat COPY cmd sh  usr local bin cmd sh RUN chmod  x  usr local bin cmd sh CMD    usr local bin cmd sh     Finally  we ll need to set up port-forwarding in cmd sh   I found that nc  even with the -l and -k options  will occasionally terminate when a request is completed  so I m using a while-loop to ensure that it s always running     cmd sh     usr bin env bash  while nc -l -p 6379 -k -c  nc redis 6379     true  do true  done  amp   tail -f  dev null   Or any other command that never exits

[docker] Docker compose port mapping

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