Question: how to form a URI with expose?

[sajith]

I have an application that expects a MONGODB_CONNSTRING environment variable, and used a tox.ini like below:

[testenv]
deps =
    [test]

commands =
    pytest

setenv =
    MONGODB_CONNSTRING = mongodb://guest:guest@localhost:27017/

[docker:mongo]
image = mongo:7.0.11
 
ports =
    27017:27017/tcp

In the pre-5.0.0 days of tox-docker, the above tox.ini worked just fine in most cases. Now that ports is deprecated, I am having a hard time with the new expose thing. This does not work:

[testenv]
deps =
    [test]

commands =
    pytest

setenv:
    MONGODB_CONNSTRING = mongodb://guest:guest@localhost:{env:MONGO_PORT}/

[docker:mongo]
image = mongo:7.0.11

expose =
    MONGO_PORT=27017/tcp

The above does not work because tox expands MONGODB_CONNSTRING to mongodb://guest:guest@localhost:/. Tox does not raise an error here unlike what the documentation says.

How can I form a MONGODB_CONNSTRING here? Refactoring the application to use MONGO_PORT would be an inconvenience, since that code's "owner" is not me. Not everyone in the team uses tox-docker, so refactoring in that manner would be a hard-sell.

Going back to older versions of tox-docker is also an inconvenience, because of this error:

"docker.errors.DockerException: Error while fetching server API version: Not supported URL scheme http+docker"

The above is because of this docker-py issue. Now I have to pin requests at 2.31.0, which is a hassle, and may not be always possible.

[dcrosta]

Your best bet here is probably to write a wrapper script that sets the MONGODB_CONNSTRING env var before invoking your tests/your application. That wrapper can be the place that knows about tox-docker's env vars. Something like this might work:

#!/bin/bash

export MONGODB_CONNSTRING=mongodb://guest:guest@localhost:${MONGO_PORT}/
exec $@

[sajith]

@dcrosta Thank you. I prefer going down the refactoring route, I think. That feels less "workaround-y", for lack of a better word. Please feel free to close this issue if you need to. :-)

Do you think tox not expanding {env:MONGO_PORT} in the above instance is an issue that should be reported? Perhaps it is reading comprehension failure from my part, but from the documentation it is not clear to me that environment variable substitution is not supposed to work under setenv. In fact setenv's description links directly to the notes about environment variable substitutions.

[dcrosta]

I agree with your reading of the docs, and that does seem like a bug, yeah. I'd report it to https://github.com/tox-dev/tox