shell - Docker compose won't find $PWD environment variable

Question

Here's my docker-compose:

version: '2'
services:
  couchpotato:
    build:
        context: ./couchpotato
        dockerfile: Dockerfile
    ports:
     - 5050:5050
    volumes:
     - "${PWD}/couchpotato/data:/home/CouchPotato/data/"
     - "${PWD}/couchpotato/config:/home/CouchPotato/config/"

When I run it inside the shell, in the directory of the docker-compose.yml, I get:

WARNING: The PWD variable is not set. Defaulting to a blank string.

and the compose starts with PWD being empty.

I don't see any error in the file, as seen here: https://docs.docker.com/compose/environment-variables/

Answer 1

You don't need ${PWD} for this, you can just make the path relative and compose will expand it (one major difference between compose paths and those processed by docker run).

version: '2'
services:
  couchpotato:
    build:
        context: ./couchpotato
        dockerfile: Dockerfile
    ports:
     - 5050:5050
    volumes:
     - "./couchpotato/data:/home/CouchPotato/data/"
     - "./couchpotato/config:/home/CouchPotato/config/"

As for why compose doesn't see this variable, that depends on your shell. Compose looks for an exported environment variable, contents of the .env file, and command line flags to the docker-compose command. If each of those comes up empty for the variable, you'll get that warning.