Local hostnames for Docker containers

OK,

so since it seems that there is no native way to do this with Docker, I finally opted for this alternate solution from Ryan Armstrong, which consists in dynamically updating the /etc/hosts file.

I chose this since it was convenient for me since this works as a script, and I already had a startup script, so I could just append this function in to it.

The following example creates a hosts entry named docker.local which will resolve to your docker-machine IP:

update-docker-host(){
    # clear existing docker.local entry from /etc/hosts
    sudo sed -i '' '/[[:space:]]docker\.local$/d' /etc/hosts

    # get ip of running machine
    export DOCKER_IP="$(echo ${DOCKER_HOST} | grep -oE '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}')"

    # update /etc/hosts with docker machine ip
    [[ -n $DOCKER_IP ]] && sudo /bin/bash -c "echo \"${DOCKER_IP}   docker.local\" >> /etc/hosts"
}

update-docker-host

This will automatically add or udpate the /etc/hosts line on my host OS when I start the Docker machine through my startup script.

Anyways, as I found out during my research, apart from editing the hosts file, you could also solve this problem by setting up a custom DNS server:

Also found several projects on Github which apparently aim to solve this problem, although I didn't try them:

• https://github.com/jpetazzo/pipework
• https://github.com/bnfinet/docker-dns
• https://github.com/gliderlabs/resolvable

Extending on @eduwass's own answer, here's what I did manually (without a script).

1. As mentioned in the question, define the domainname: myapp.dev and hostname: www in the docker-compose.yml file
2. Bring up your Docker containers as normal
3. Run docker-compose exec client cat /etc/hosts to get an output of the container's hosts file (where client is your service name) (Output example: 172.18.0.6 www.myapp.dev)
4. Open your local (host machine) /etc/hosts file and add that line: 172.18.0.6 server.server.dev

If your Docker service container changes IPs or does anything fancy you will want a more complex solution, but this is working for my simple needs at the moment.

Another solution would be to use a browser with a proxy extension sending the requests through a proxy container that will know where to resolve the domains to. If you consider using jwilder/nginx-proxy for production mode, then your issue can be easily solved with mitm-nginx-proxy-companion.

Here is an example based on your original stack:

version: '3.3'

services:

  server:
    build: ./server
    working_dir: /app
    volumes:
      - ./server:/app

  client:
    environment:
      - VIRTUAL_HOST: client.dev
    image: php:5.6-apache
    volumes:
    - ./client:/var/www/html

  database:
    image: postgres:9.4
    restart: always
    environment:
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=root
      - POSTGRES_DB=dbdev
      - PG_TRUST_LOCALNET=true
    volumes:
      - ./database/scripts:/docker-entrypoint-initdb.d # init scripts

  nginx-proxy:
    image: jwilder/nginx-proxy
    labels:
      - "mitmproxy.proxyVirtualHosts=true"
    volumes:
      - /var/run/docker.sock:/tmp/docker.sock:ro

  nginx-proxy-mitm:
    dns:
      - 127.0.0.1
    image: artemkloko/mitm-nginx-proxy-companion
    ports:
      - "8080:8080"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro

• Run docker-compose up
• Add a proxy extension to your browser, with proxy address being 127.0.0.1:8080
• Access http://client.dev

The request will follow the route:

• Access a local development domain in a browser
• The proxy extension forwards that request to mitm-nginx-proxy-companion instead of the “real” internet
• mitm-nginx-proxy-companion tries to resolve the domain name through the dns server in the same container
  • If the domain is not a “local” one, it will forward the request to the “real” internet
  • But if the domain is a “local” one, it will forward the request to the nginx-proxy
• The nginx-proxy in its turn forwards the request to the appropriate container that includes the service we want to access

Side notes:

• links removed as it's outdated and is replaced by Docker networks
• you don't need to add domain names to server and database containers. client will be able to access them on server and database domains because they are all in the same network (similar to what link was doing previously)
• you don't need to use ports on server and database containers because it only forwards ports to be used through 127.0.0.1. PHP in client container will do only "back-end" requests to other containers, and because those containers are in the same network, you already can access them with database:5432 and server:3000. The same goes for server <-> database connections.
• I am the author of mitm-nginx-proxy-companion