docker compose override a ports property instead of merging it - docker

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

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)

Answer 2

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 3

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 4

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

Answer 5

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