feat(core): Private registry

[Tranquility2]

Ref #562

This enhancement adds capability to utilize the env var DOCKER_AUTH_CONFIG in-order to login to a private docker registry.

[alexanderankin]

i wonder if this is what the java client does underneath, have almost no opportunity to find out independently. i explored the testcontainers side of java yesterday and realized that i need to look at docker-java to find any real answers anyways.

[Tranquility2]

Added tests

[Tranquility2]

Some documentation on how I tested it:
https://gist.github.com/Tranquility2/20652b77a012ee54ae1c8ca021aea1ff

[alexanderankin]

wdyt about testing using this module - https://github.com/testcontainers/testcontainers-python/tree/main/modules/registry - i know it inverts the dependencies on their head a bit. maybe we can just copy and paste the code as it is just a part of the test suite and therefore not actually being published to pypi. doesn't have to be a part of this PR, just think that would be the most comprehensive/on-brand test.

maybe its not actually a blocker, just pausing to think cause when this is merged, there is no more fixes for 4.4 line (RP will set the version in #551 to 4.5.x)

[Tranquility2]

was thinking the same thing :)
I had the exact same doubt as its not really a best practice but fits like a glove for a more comprehensive test.
Do you think it should be in this PR or another? In any case I'll be happy to add it.

[alexanderankin]

Ok, so I'll just compile some research here for the future:

• the docker api expects a json object with username and password properties - base 64 encoded in the X-Registry-Auth header
• the login method will call add_auth - which saves things into a dict - which get used to set the auth header during inspect, pull and push (and also in plugin and service) but not create container, like java does: createCmdExec, AbstractDockerCommandExec.

If this actually works and doesn't break anything, I think this is as close as were going to get.

[alexanderankin]

Do you think it should be in this PR or another? In any case I'll be happy to add it.

probably another at this point. its more than welcome, but have to keep merging things or else they get stale and conflicted and unmergable.