Global/default override for all services

[durera]

What I want to do is separate my environment specific tweaks into an override.yml, nothing fancy there ... however my overrides will be exactly the same for every single service deployed & I want to avoid having to write out the same override for every single service (and continually add new sections to the override as new services are introduced).

Instead I would like to create one definition that says "apply to this override to every single service". Does such a concept exist already that I am perhaps missing?

Example ...

docker-compose.yml:

  aservice:
    image: whatever1
    environment:
      FOO: BAR

another docker-compose.yml:

  anotherservice:
    image: whatever2

my docker-compose.override.yml:

  <magickeyword>:
    environment:
      FLIBBLE: flobble
    dns:
      - server1
      - server2

Now, every service deployed would have DNS server1 & server2 and the environment variable FLIBBLE.

I realise I could do this if all services were extending the same base service as I could apply the override to that, but is there anyway to set global/default override without a common extension?

At the moment I have a hack that involves a generated override scanning for any defined services and generate the override file on the fly, but it seems like a use case that I can't be the first person to run into so wondered if perhaps I have just missed the obvious solution to this in compose.

[shin-]

You could just have a base.yml file in each project folder with a base service containing just your environment key, then have each service extend the base service.

[saml]

This is no longer a good solution given that extends: is removed in 3.x moby/moby#31101

[shin-]

@saml check out #5140

[mbrodala]

@shin- Rather old but the feature for custom options doesn't seem to help for the issue mentioned here. AFAIS one still cannot define global defaults for all services. You either need to prepare all services accordingly or use a generated override file as described here.