docker compose override a ports property instead of merging it

Question

My docker compose configs look like this:

docker-compose.yml

version: '3.5'

services:
    nginx:
        ports:
            - 8080:8080

docker-compose.prod.yml

version: '3.5'

services:
    nginx:
        ports:
            - 80:80

Now, when I run command: docker-compose -f docker-compose.yml -f docker-compose.prod.yml up the nginx exposes on host machine two ports: 8000 and 80, because it merges ports properties:

version: '3.5'

services:
    nginx:
        ports:
            - 8080:8080
            - 80:80

Is there a way to override it? I want to expose only port 80.

Answer 1

it isn't possible a the moment but I found quite good way to fix this issue using the command yq. You need to remove the ports from the original file.

Example:
Be careful this command will remove the nginx ports from your current docker-compose.yml (because of the -i option)

yq e -i 'del(.services.nginx.ports)' docker-compose.yml

You can execute this command on your deployment script or manually before your docker-compose up -d

There's also an open issue on docker-compose, that you may want to check once in a while.

Answer 2

Just keep the docker-compose.yml super simple and add the ports in another file docker-compose.develop.yml, then run it like docker-compose -f docker-compose.yml -f docker-compose.develop.yml up. This way you can separate it from your docker-compose.override.yml file.

So you will have three files:

|- docker-compose.yml # no ports specified
|- docker-compose.override.yml # ports 8080:8080
|- docker-compose.develop.yml #ports 80:80

Refer to this post for longer explanation: https://mindbyte.nl/2018/04/04/overwrite-ports-in-docker-compose.html

Answer 3

I've faced the same problem. The proposed solution with docker-compose.override.yml sounds pretty well and is also an official one.

Although for some of my own projects I've applied the erb template engine to make docker-compose.yml.erb file compile for multiple environments. In short I use:

COMPOSE_TEMPLATE_ENV=production erb docker-compose.yml.erb > docker-compose.yml
COMPOSE_TEMPLATE_ENV=production erb docker-compose.yml.erb > docker-compose-production.yml

And then I can use the ENV['COMPOSE_TEMPLATE_ENV'] in my template and also the syntax of ERB, so only one file to configure and no worries about piplening them properly. Here's the short post article I've written about it