Can you define optional docker-compose services?

Is there a way to define a Docker Compose service such that it is only brought up when you explicitly request it?

That is to say:

docker-compose up

would not start it, but

docker-compose up optional_service

would.

One way to achieve that is to define your optional service in a different compose file. Then to start the optional service, run:

$ docker-compose -f docker-compose.yml -f optional-service.yaml up

For example, if I have a docker-compose.yml file that looks like:

version: '2.1'
services:
  lb:
    image: nginx:1.13           
  db:
    image: redis:3.2.9

I can extend it with an optional-service.yml that looks like:

version: '2.1'
services:
  busy:
    image: busybox

Notice that both compose files must use the same Compose file version.

You can read more about it in the Compose documentation.

The extend keyword has been removed in version 3.x.

I faced the same issue and this is what I did:

From Docker's official docs, we can use a COMPOSE_FILE environment variable in a .env file.
The way this works is: when you do docker-compose up, instead of reading docker-compose.yml, it will read all the compose files specified in COMPOSE_FILE variable.

For example,

COMPOSE_FILE=docker-compose.yml:./optional/docker-compose.prod.yml

the good part is that:
- the .env file is auto-read (if located in the same level as docker-compose.yml), when we invoke docker-compose up.
- no need to specify each file with a -f flag in CLI.
The one drawback is: need to create separate compose files for each service you wish to make optional.

Note: separate file names with a : in case of linux or ; in case of windows.

来源：https://stackoverflow.com/questions/45680958/can-you-define-optional-docker-compose-services

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