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faradayio / cage

Develop and deploy complex Docker applications
http://cage.faraday.io
Apache License 2.0
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`status` doesn't work on a container with environment variables in the `ports` section #87

Closed khuey closed 4 years ago

khuey commented 6 years ago 
ports:
  - $PORT:80

This will fail to print out a status entry for the container with Error: cannot parse without interpolating environment variables '$PORT:80'

emk commented 6 years ago

As I've previously mentioned, environment variable interpolation in cage has really poorly-defined semantics, and it should almost always be replaced with pods/targets/$TARGET/common.env variables instead. The core problem is that sometimes people want cage to interpolate, and sometimes they want docker-compose to interpolate, and sometimes cage computes new values based on existing values (because cage is basically just pipeline processor for transforming docker-compose.yml files in various ways). So you inevitably end up with a nasty mismatch of things interpolated at cage time and things interpolated at docker-compose time.

As far as I can tell, the only workable long-term solution is to completely forbid environment variable interpolation in cage. There may be another solution, but I don't see it right now.

What I would need to reconsider: A rigorous, well-defined solution to how interpolation should work, that:

I'm also open to solutions about improving pods/targets to handle new use cases. But I don't think it's a good idea to try to address these individual issues in an ad hoc fashion, because we'll just keep running into them every other week, and there will be no actual solution other than to add increasing numbers of dubious hacks. And we know from bitter experience with the original Ruby version of cage that adding dubious hacks is very tempting and that it will end very badly. :-(

khuey commented 6 years ago

I think that ports should probably be retrieved from the docker daemon rather than reinterpolating the yaml.

emk commented 4 years ago

Hello! cage was very minimally maintained for several years, and I'm sorting through old issues. I'm going to go ahead and close this issue for inactivity, but please feel free to reopen it if anybody is still interested.