CODEWITHSUNDEEP
curldockerdnsdocker-composedocker-network
Gihan
Gihan

Reputation: 4283

Docker custom dns resolve among containers

I have following docker-compose.yml

php:
    build: ./phpfpm
    volumes:
        - ~/works/codes:/code

web:
    image: nginx:latest
    ports:
        - "80:80"
    volumes:
        - ~/works/codes:/code
        - ./nginx/etc/conf.d/virtual.conf:/etc/nginx/conf.d/virtual.conf
        - ./nginx/var/log/nginx:/var/log/nginx
    links:
        - php

I've 2 virtual hosts setup inside web container

app.lan
api.lan

In my php application I do curl to api.lan. But it throws Could not resolve host: api.lan

In my docker host I've added following to /etc/hosts file

127.0.0.1 app.lan
127.0.0.1 api.lan

I can curl from docker host machine to api.lan without a problem. But seems web container doesn't resolve name from docker host machine.

If I find the web container's ip and put that into the php container's hosts file as follows it works.

172.18.0.5 api.lan

But how do I automate this on docker compose. Or any other best practices for this?

In addition if I cat /etc/resolve.conf of either container I can find following.

search local
nameserver 127.0.0.11
options ndots:0

What's this 127.0.0.11? Is it the host machine?

I'm on "Docker for mac" v 1.12.1

Upvotes: 0

Views: 2247

Answers (3)

Gihan
Gihan

Reputation: 4283

As @Chris Pointed out I need to use docker's extra_hosts and also I needed to create a network and assign IPs to each docker container.

Following is my full docker-compose.yml

version: "2"

networks:
    lan_0:
        driver: bridge
        ipam:
            driver: default
            config:
                - subnet: 172.19.0.0/24
                  gateway: 172.19.0.21

services:
    php:
        build: ./phpfpm
        volumes:
            - ~/works/codes:/code
        extra_hosts:
            - "api.lan:172.19.0.21"
        networks:
            lan_0:
                ipv4_address: 172.19.0.22

    web:
        image: nginx:latest
        ports:
            - "80:80"
        volumes:
            - ~/works/codes:/code
            - ./nginx/etc/conf.d/virtual.conf:/etc/nginx/conf.d/virtual.conf
            - ./nginx/var/log/nginx:/var/log/nginx
        links:
            - php
        networks:
            lan_0:
                ipv4_address: 172.19.0.21

Upvotes: 2

dnephin
dnephin

Reputation: 28040

In my php application I do curl to api.lan

Don't do that. Use the hostnames provided by docker web and php (the names you gave to the services in your docker-compose.yml are created as hostnames that can be used by other containers.

Upvotes: 1

Chris Tanner
Chris Tanner

Reputation: 1650

127.0.0.11 is docker's internal dns that allows containers to communicate with each other directly by name ('web' and 'php' in your case).

You can add extra entries to docker using extra hosts in docker-compose.yml.

Upvotes: 1

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