Fix: correect header retrieval for urllib3 compatibility

[franck-ada]

What type of PR is this?
/kind bug
/kind deprecation

What this PR does / why we need it:
Correct issue link to upgrade of urlib3

Which issue(s) this PR fixes:
Fixes #2280 / #2477

Special notes for your reviewer:
Does this PR introduce a user-facing change?
NONE

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[Copilot]

Pull request overview

This PR fixes header retrieval in the RESTResponse class to support urllib3 v2.x compatibility. The PR addresses issue #2280 by adding compatibility checks that prefer the newer headers attribute (available in urllib3 v2.x) before falling back to the deprecated getheaders() and getheader() methods.

Note: The PR title contains a typo: "correect" should be "correct".

Key changes:

• Added hasattr() checks to detect the presence of the headers attribute on urllib3 response objects
• Updated getheaders() to use headers.items() when available, falling back to getheaders() for older versions
• Updated getheader() to use headers.get() when available, falling back to getheader() for older versions

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[Copilot]

The docstring states "Returns a dictionary of the response headers" but the method returns headers.items() which returns an iterable of tuples (key-value pairs), not a dictionary. Consider updating the docstring to accurately reflect the return type, such as "Returns an iterable of header key-value pairs" or "Returns header items as tuples".

Suggested change

	"""Returns a dictionary of the response headers."""
	"""Returns an iterable of header key-value pairs (tuples)."""

[efussi]

Here is another occurrence of getheaders:

python/kubernetes/client/exceptions.py

Line 91 in a49d85d

self.headers = http_resp.getheaders()

From my sniff testing, this needs to be changed as well.

[franck-ada]

http_resp

I was looking at it. this http_resp is an instance of RESTResponse so it should stay as it is

[efussi]

http_resp

I was looking at it. this http_resp is an instance of RESTResponse so it should stay as it is

@franck-ada I was testing an ansible playbook with urllib3 2.6.0 patched like this:

sed -i -e 's/urllib3_response.getheaders()/urllib3_response.headers/' -e 's/urllib3_response.getheader(name, default)/urllib3_response.headers.get(name, default)/' \
    $site_packages/kubernetes/client/rest.py

When trying to delete a configmap that doesn't exist through ansible's k8s task, I still got this error:

TASK [wca-base : Delete configmap in dev] *************************************************************************************************************************************************************************
fatal: [localhost]: FAILED! =>                           
    ansible_facts:                                                                                                             
        discovered_interpreter_python: /home/vagrant/.cache/venv/ansible/bin/python3.12                                        
    changed: false                                                                                                             
    msg: 'Failed to retrieve requested object: ''HTTPResponse'' object has no attribute                                                                                                                                                                       
        ''getheaders'''                                                                                                                                                                                                                                       

I had to add this additional patch to get past this error:

sed -i -e 's/http_resp.getheaders()/http_resp.headers/' \
    $site_packages/kubernetes/client/exceptions.py

Unfortunately, I didn't find a way yet to have ansible print the full stack trace.