How to get ip and port in one docker container form other one with environment variables?

Question

I use Docker-Compose.

Some time ago i used this code. Nginx used ip and port from environment variables like this "API_PORT_5432_TCP_ADDR" "API_PORT_5432_TCP_PORT".

Now i can not to connect from one container to other. I found some description in the documentation, that "links" should do such work, i mean it creates environment variables and later i can get it in other container. But i do not know, what i do wrong. Are there ways to resolve that problem? Will be glad if you give me links or some code lines.

Thank you.

version: '3.0'
    services:
      ubuntubase:
        build: ./ubuntu-base 
      backend:
          build: ./backend
          links:
              - postgresql:db
          expose:
              - "6060"
          depends_on:
              - ubuntubase
              - postgresql
      nginxreverseproxy:
          build: ./nginx-reverse-proxy
          expose:
              - "80"
              - "443"
          links:
              - backend:api
          ports:
              - "80:80"
          volumes:
              - ./logs/:/var/log/nginx/
          depends_on:
              - ubuntubase
              - backend


      postgresql:
        restart: always
        image: sameersbn/postgresql:9.6-2
        expose:
          - "5432"
        depends_on:
            - ubuntubase
        environment:
          - DEBUG=false
          - DB_USER=...
          - DB_PASS=...
          - DB_NAME=...  
        volumes:
          - /srv/docker/postgresql:/var/lib/postgresql

score 1 · Accepted Answer · answered Mar 22 '17 at 17:13

links does not work via environment variables. It works by exposing the service's name as if it were a DNS hostname. So in your example, your "nginxreverseproxy" service can connect to the "backend" service by using the hostname "api".

By default, these links use the name of the service, i.e. if you had specified:

links:
  - backend

Then you would connect to "backend". If you supply another name (as you did with "api") then that name is exposed as an alias instead.

However this does not communicate the port. If you want to use a non-default port, you will probably have to set an environment variable yourself, and then tell your service to use it.

For example, your "backend" exposes port 6060. If your "nginxreverseproxy" does not know that, you can tell it with an environment variable.

nginxreverseproxy:
  environment:
    - BACKEND_PORT=6060

And then tell the nginx service to use that environment variable, plus the hostname "api", to connect.

How to get ip and port in one docker container form other one with environment variables?

1 Answers1