docker: always use API version negotiation when initializing clients

[pkazmierczak]

During a refactoring of the docker driver in #23966 we introduced a bug: API version negotiation option was not passed to every new client call.

Fixes #24212
internal ref: https://hashicorp.atlassian.net/browse/NET-11337

[tgross]

LGTM

I realize it's not super realistic for us to exercise the version negotiation in the unit tests, but can you post here how you tested this fixes #24212 just so we have a note on that for the future?

[pkazmierczak]

can you post here how you tested this fixes #24212 just so we have a note on that for the future?

I reproduced the exact steps from the ticket. I used an aws instance, installed an older docker version and tested with nomad 1.8.4, 1.9 and then a binary from this branch. It was easy to reproduce the bug and check the solution works.

Automating this is somewhat non-trivial. We already use incompatible dockerd in our e2e, but we never point to an endpoint in our plugin config, so that code path wasn't exercised (as the reporter mentions, if endpoint isn't explicitly configured, API version negotiation works). Changing plugin configuration of our nomad clients on the fly to actually test this is hard. Mocking a simple dockerd—an approach I just tried—is also harder than expected. I might get back to this but it'll take a while.