[27.x backport] fix: ctx on run image pull

[Benehiko]

• backport fix: ctx on run image pull #5645
• Fixes Pulling image with docker run doesn't cancel gracefully #5639

After some digging I found that we don't actually explicitly return an error on the pullImage function here. Once the context is cancelled the response is closed since the API client uses http.NewRequestWithContext which then exits the jsonmessage.DisplayJSONMessagesToStream(responseBody, out, nil) without any errors.

The following API request to ContainerCreate then immediately fails since the context is closed, which then returns an error.

See this section of the code, it fails to find the image, then pulls the image, and continues to retry creating a container - on this second retry it only then returns with the context error.
https://github.com/docker/cli/blob/master/cli/command/container/create.go#L271-L289

Writing a test for this means that we are building into the test an assumption that we won't error on the pullImage function, but rather on the second call to ContainerCreate. I'll push what I have, but I honestly think that we will get tripped up by the pullImage function again since it's not context aware - actually more so the jsonmessage package it is using is actually the root cause found in Moby here. It's a bit of a hornets nest since it gets used in many places and by refactoring/improving this it could cause edge case bugs.

- What I did
Delay stripping the cancel from the function ctx so we can still cancel the createContainer function.

cli/cli/command/container/run.go

Line 142 in e4e0ea2

containerID, err := createContainer(ctx, dockerCli, containerCfg, &runOpts.createOptions)

- How I did it

- How to verify it
Unit test

- Description for the changelog

Fixed bug preventing image pulls from being cancelled during `docker run`.

- A picture of a cute animal (not mandatory but encouraged)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.54%. Comparing base (47a4f70) to head (530cf09).
Report is 4 commits behind head on 27.x.

Additional details and impacted files

@@           Coverage Diff           @@
##             27.x    #5654   +/-   ##
=======================================
  Coverage   58.54%   58.54%           
=======================================
  Files         346      346           
  Lines       29335    29333    -2     
=======================================
+ Hits        17173    17174    +1     
+ Misses      11184    11182    -2     
+ Partials      978      977    -1     

[thaJeztah]

not a blocker (but if you want to re-apply, let me know); we try to use the -x option when cherry-picking, so that a reference to the original commit is added in the commit message, e.g.;

git commit -s -S -x 30a73ff19c407eee75de489355154ce1f35231a8

The x option adds an extra line to the commit message, which can be useful to correlate changes and/or track-back origin;

(cherry picked from commit 30a73ff19c407eee75de489355154ce1f35231a8)

[thaJeztah]

LGTM (but left a suggestion, let me know if you want to fix up the cherry-pick)

[Benehiko]

@thaJeztah updated the cherry-pick with your suggestions

[thaJeztah]

LGTM

thanks! Let me bring this one in 👍