dockerfile - How to pass arguments within docker-compose?

Question

Docker 1.9 allows to pass arguments to a dockerfile. See link: https://docs.docker.com/engine/reference/builder/#arg

How can I pass the same arguments within docker-compose.yml?
Please provide an example too, if possible.

Answer 1

Now docker-compose supports variable substitution.

Compose uses the variable values from the shell environment in which docker-compose is run. For example, suppose the shell contains POSTGRES_VERSION=9.3 and you supply this configuration in your docker-compose.yml file:

db:
  image: "postgres:${POSTGRES_VERSION}"

When you run docker-compose up with this configuration, Compose looks for the POSTGRES_VERSION environment variable in the shell and substitutes its value in. For this example, Compose resolves the image to postgres:9.3 before running the configuration.