Docker Swarm with image versions externalized to .env file

Question

I used to externalized my image versions to my .env file. This make it easy to maintain and I don't modify my docker-compose.yml file just to upgrade a version, so I'm sure I won't delete a line by mistake or whatever.

But when I try to deploy my services with stack to the swarm, docker engine complains that my image is not a correct reposity/tag, with the exact following message :

Error response from daemon: rpc error: code = 3 desc = ContainerSpec: "GROUP/IMAGE:" is not a valid repository/tag

To fix this, I can fix the image version directly in the docker-compose.yml file. Is there any logic here or it that a bug? But this mixes fix part of the docker-compose and variable ones.

Cheers, Olivier

Answer 1

you can create a deploy.sh

export $(cat .env) > /dev/null 2>&1; docker stack deploy ${1:-STACK_NAME}

• The .env parses without regular expressions or unstable tricks.
• Errors on stderr produced by #comments inside the .env will be redirected to stdin (2>&1)
• Undesired prints of all export and error now on stdin too, are redirected to /dev/null. This prevents console flood.
• Those errors do not prevent .env being parsed correctly.

We can define STACK_NAME in our .env but we can also pass our customized stack_name

. deploy.sh <stack_name> (stack_name opcional)

This workaround gave me headaches for 3 nights