docker compose override a ports property instead of merging it

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.

This behaviour is documented at https://docs.docker.com/compose/extends/#adding-and-overriding-configuration

> For the multi-value options ports, expose, external_links, dns, dns_search, and tmpfs, Compose concatenates both sets of values

Since the ports will be the concatenation of the ports in all your compose files, I would suggest creating a new docker-compose.dev.yml file which contains your development port mappings, removing them from the base docker-compose.yml file.

As Nikson says, you can name this docker-compose.override.yml to apply your development configuration automatically without chaining the docker-compose files. docker-compose.override.yml will not be applied if you manually specify another override file (e.g. docker-compose -f docker-compose.yml -f docker-compose.prod.yml)

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.

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

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

Use .override.yml file for overriding properties and a clear separation of properties need to be overridden

docker-compose.override.yml

Example:

version: '3.5'

services:
    nginx:
        ports:
            - 80:80

Default:

docker-compose up

will use your docker-compose.yml and docker-compose.override.yml files

Reference: docker-compose multiple compose