Fix UTF-8 failures in Watch

[davidopic]

What type of PR is this?

/kind bug

What this PR does / why we need it:

With the old implementation of kubernetes.watch.Watch.stream(), users may experience intermittent crashes when subscribed to resources that include multi-byte UTF-8 characters (for example, ConfigMaps with non-ASCII characters in the .data.* fields). The bug lies in kubernetes.watch.iter_resp_lines, which decodes each bytes segment to a UTF-8 string without waiting for the rest of the event to be received. When that bytes segment ends with only part of a multi-byte sequence, the .decode step will fail. Here's how this symptom presents:

UnicodeDecodeError: 'utf-8' codec can't decode bytes in position 2046-2047: unexpected end of data

The new implementation of iter_resp_lines buffers partial events in a bytearray rather than a str, decoding only after a complete event has been received. Furthermore, the call to .decode now includes the argument, errors="replace", which uses the canonical UTF-8 fallback character, �, when encountering invalid UTF-8.

To confirm the fix, I added three new tests, two of which failed using the old implementation.

Which issue(s) this PR fixes:

Fixes #2087

Special notes for your reviewer:

iter_resp_lines is only called by Watch.stream, and the interface did not change.

The old code implicitly assumed that only bytes and str were valid segment types, and that assumption has now been made explicit with a TypeError.

I only tested with python 3.11. I assume that CI will test the code against each of the officially supported python versions. If that's not the case, my code should be reviewed with an eye for any new features I unknowingly relied upon.

Does this PR introduce a user-facing change?

Fix UTF-8 failures in Watch

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

N/A

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: davidopic / name: David E (934d026)

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[roycaihw]

/assign

[superosku]

Hi! Any updates on this?

[dolshevsk]

Also interested in this PR to be merged

[superosku]

@roycaihw any updates regarding this?

[roycaihw]

Sorry for the late response. LGTM! Thanks for the contribution!

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: davidopic, roycaihw

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