[extension/k8s leader elector] Initial implementation for the extension leader elector - basic structure

[rakesh-garimella]

Description

This extension could be used to run multiple receivers in HA mode. The receiver which has successfully acquired the lease becomes active and thus becomes leader.

The extension uses k8s.io/client-go/tools/leaderelection to perform leader election. The component that owns the lease becomes the leader and runs the function defined in onStartedLeading. If the leader loses the lease, it runs the function defined in onStoppedLeading, stops its operation, and waits to acquire the lease again.

The config would like this:

receivers:
  my_awesome_reciever:
    leader_elector: k8s_leader_elector
exporters:
  debug:
    verbosity: detailed
extensions:
  k8s_leader_elector:
    auth_type: kubeConfig
    lease_name: foo
    lease_namespace: default

service:
  extensions: [k8s_leader_elector]
  pipelines:
    metrics:
      receivers: [my_awesome_receiver]
      exporters: [debug]
  telemetry:
    logs:
      level: debug

Link to tracking issue

Fixes
#34460

Testing

unit tests have been added

Documentation

README file has been added

[dmitryax]

Can we always rely on this to be unique within the cluster? Probably not. I think this should be a configurable option with this value as a default.

[codecov]

Codecov Report

Attention: Patch coverage is 53.84615% with 24 lines in your changes missing coverage. Please review.

Project coverage is 79.65%. Comparing base (499df64) to head (a654357).
Report is 23 commits behind head on main.

Files with missing lines	Patch %	Lines
extension/k8sleaderelector/factory.go	74.28%	6 Missing and 3 partials ⚠️
extension/k8sleaderelector/config.go	20.00%	7 Missing and 1 partial ⚠️
extension/k8sleaderelector/extension.go	0.00%	7 Missing ⚠️

❌ Your patch status has failed because the patch coverage (53.84%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.
❌ Your project status has failed because the head coverage (79.65%) is below the target coverage (85.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #37266      +/-   ##
==========================================
+ Coverage   79.60%   79.65%   +0.05%     
==========================================
  Files        2308     2315       +7     
  Lines      216392   217241     +849     
==========================================
+ Hits       172253   173051     +798     
- Misses      38381    38414      +33     
- Partials     5758     5776      +18     

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