Fix issue with externalTrafficPolicy: Local for single-stack services on dual-stack nodes

[brandond]

Proposed Changes

Fix issue with local traffic policy for single-stack services on dual-stack nodes.

Just enable IP forwarding for all address families regardless of service address families.

Note: I confirmed that this works even on a node with ipv6 disabled via net.ipv6.conf.all.disable_ipv6=1 sysctl.

Types of Changes

bugfix

Verification

#9949 (comment)

Testing

Linked Issues

• LoadBalancers crashing after updating from 1.27.3 to 1.29.3 #9949

User-Facing Change

Further Comments

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 13 lines in your changes are missing coverage. Please review.

Project coverage is 24.87%. Comparing base (81cd630) to head (6f47182).
Report is 3 commits behind head on master.

Files	Patch %	Lines
pkg/cloudprovider/servicelb.go	0.00%	13 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #9963       +/-   ##
===========================================
- Coverage   49.63%   24.87%   -24.77%     
===========================================
  Files         158      158               
  Lines       14017    14010        -7     
===========================================
- Hits         6958     3485     -3473     
- Misses       5755     9834     +4079     
+ Partials     1304      691      -613     

Flag	Coverage Δ
e2etests	4.84% <0.00%> (-41.30%)	⬇️
inttests	18.94% <0.00%> (-18.11%)	⬇️
unittests	16.57% <0.00%> (+0.01%)	⬆️

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[damdo]

@brandond @manuelbuil is this ready to merge now? Thanks!

[manuelbuil]

@brandond @manuelbuil is this ready to merge now? Thanks!

We are currently on code freeze. We can't merge anything

[damdo]

I see @manuelbuil thanks.
My k3s cluster is currently impacted by this issue.
I'd appreciate if this could merge when the code freeze lifts, and whether this could be backported to 1.29.z.
Thanks!

[manuelbuil]

I see @manuelbuil thanks. My k3s cluster is currently impacted by this issue. I'd appreciate if this could merge when the code freeze lifts, and whether this could be backported to 1.29.z. Thanks!

Code freeze is normally lifted around the last week of the month. We will backport to all upstream maintained branches in June (1.29, 1.28 and probably 1.27)

[matttrach]

lgtm