Added support for quoted env vars

[kamermans]

Signed-off-by: Steve Kamerman stevekamerman@gmail.com

Resolves #2854

This PR adds support for environment variables in .env files with quoted values. The quotes can be single ' or double ", but must be the same on both ends of the value, and must immediately follow the =.

Example:

MYVAR="this is a test"

It also unescapes escaped quotes, like \":

MYVAR="this is a \"quoted\" test"

Value: this is a "quoted" test

All functionality is tested.

This problem has been thoroughly discussed in issue #2854 and there are many reasons for why docker-compose should support this.

[kamermans]

I understand that this change will also affect the documentation, so I'm happy to put in a PR for that as well.

[kolaente]

Ping @ulyssessouza @ndeloof @rumpl Any chances this will be merged?

[ulyssessouza]

The PR was closed in favor of the adoption of python-dotenv that solves the problem in a more general way. But anyways, thank you @kamermans !

[feld]

I don't know how python-dotenv solves this issue that remains as seen in #2854 (comment) ???

Can anyone clarify?

edit: I think this PR is from before docker-compose was rewritten in Go