Docker-compose, conditional statements? (e.g. add volume only if condition)

Question

I want to add a volume to my service, but only if the final user gave a folder for it. Otherwise, no volume should be mounted, for the already-prepared image has valid data in a

Answer 1

Yeah, I do not think docker-compose's format supports conditional statements.

However, two solutions could be:

1. Pass a "complex" (list-like) variable to the docker-compose such as in this example:

docker-compose.yaml:

command: ${COMMAND_PARAMS}

bash:

#!/bin/bash
if test -z $CONDITION; then
  params="-param1 ${MIPARAM1}"
else
  params="-param1 ${MIPARAM1} -param2 ${MIPARAM2}"
fi
COMMAND_PARAMS=$params docker-compose up

(credits goes to original poster on github, @shin-)

2. Prepare the default folder in the docker image in a folder named something like folder_defaults, then have the volume always defined in docker-compose.yml, but then finally, have an internal script in the docker image that checks whether the volume folder is empty, and if so ln -s to the folder_defaults; otherwise leave it as it is.

Example of the conditional script:

if [ -z "$(ls -A /a/folder)" ]; then
  do something... using /a/folder_defaults
fi