Inheritance or nesting with docker compose

Question

The best way to start our application is by using a docker compose we provide. The docker-compose starts all the services with the right configuration.

Now we would like to provide a docker-compose where the application runs with a different backend. In this compose 8 out 10 services are the same and 2 are different.

How to achieve this without code duplication? I see that a service can extend a service from another docker-compose file, however this would still require to list all the 10 services in both files.

Answer 1

With docker-compose 1.6 this should be possible.

Create a docker-compose.yml with your common services:

service01:   image: image01   links:     - service02  service02:   image: image02 

And a second file, docker-compose.prod.yml with your unique services:

service03:   image: image03   links:     - service02 

Now you can start service 01, 02 and 03 with this command:

docker-compose -f docker-compose.yml -f docker-compose.prod.yml 

For more information, see the official documentation: https://docs.docker.com/compose/extends/#multiple-compose-files

Answer 2

The easiest way to achieve this is to create a second compose file. In the second file, you can use the extend feature of Docker Compose which allows you to "inherit" services from another file: https://docs.docker.com/compose/extends/

Assuming your original file is docker-compose.yaml, you could create a swap-backend-compose.yaml:

service-one:   extends:     file: docker-compose.yaml     service: service-one  service-two:   extends:     file: docker-compose.yaml     service: service-two   environment:     - BACKEND=some_other_value 

...and so on.