Remove redundant Prometheus variable labels

[haywoodsh]

Proposed changes

Remove unused Prometheus variable labels to eliminate warning messages from Prometheus exporter. closes #4952

The worker metrics now looks like the following without any warning messages

Tests

worker

In the main branch, there were warning messages when prometheus metrics are exported. The following logs are no longer found.

level=warn ts=2024-01-30T17:18:40.810Z caller=nginx_plus.go:1258 wrongnumberoflabelsforworker%v.Forlabels%v,gotvalues:%v.Emptylabelswillbeusedinstead=0
level=warn ts=2024-01-30T17:18:40.811Z caller=nginx_plus.go:1258 wrongnumberoflabelsforworker%v.Forlabels%v,gotvalues:%v.Emptylabelswillbeusedinstead=1
level=warn ts=2024-01-30T17:18:40.812Z caller=nginx_plus.go:1258 wrongnumberoflabelsforworker%v.Forlabels%v,gotvalues:%v.Emptylabelswillbeusedinstead=2
level=warn ts=2024-01-30T17:18:40.812Z caller=nginx_plus.go:1258 wrongnumberoflabelsforworker%v.Forlabels%v,gotvalues:%v.Emptylabelswillbeusedinstead=3
level=warn ts=2024-01-30T17:18:40.812Z caller=nginx_plus.go:1258 wrongnumberoflabelsforworker%v.Forlabels%v,gotvalues:%v.Emptylabelswillbeusedinstead=4
level=warn ts=2024-01-30T17:18:40.812Z caller=nginx_plus.go:1258 wrongnumberoflabelsforworker%v.Forlabels%v,gotvalues:%v.Emptylabelswillbeusedinstead=5

In the main branch, extra labels resource_name ,resource_namespace, resource_type are found in the prometheus metrics with no values.

# HELP nginx_ingress_nginxplus_worker_connection_accepted The total number of accepted client connections
# TYPE nginx_ingress_nginxplus_worker_connection_accepted counter
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="0",pid="60",resource_name="",resource_namespace="",resource_type=""} 3
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="1",pid="50",resource_name="",resource_namespace="",resource_type=""} 0
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="2",pid="52",resource_name="",resource_namespace="",resource_type=""} 0
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="3",pid="54",resource_name="",resource_namespace="",resource_type=""} 0
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="4",pid="55",resource_name="",resource_namespace="",resource_type=""} 0
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="5",pid="57",resource_name="",resource_namespace="",resource_type=""} 0

In this branch, worker metrics exported in this branch no longer contain the redundant values:

# HELP nginx_ingress_nginxplus_worker_connection_accepted The total number of accepted client connections
# TYPE nginx_ingress_nginxplus_worker_connection_accepted counter
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="0",pid="44"} 3
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="1",pid="46"} 0
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="2",pid="48"} 0
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="3",pid="49"} 0
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="4",pid="52"} 0
nginx_ingress_nginxplus_worker_connection_accepted{class="nginx",id="5",pid="53"} 0

http cache

No changes in logs and metrics as http cache variable labels are not processed in the prometheus exporter.

# HELP nginx_ingress_nginxplus_cache_bypass_bytes Total number of bytes returned from cache bypasses
# TYPE nginx_ingress_nginxplus_cache_bypass_bytes counter
nginx_ingress_nginxplus_cache_bypass_bytes{class="nginx",zone="jwk"} 0
nginx_ingress_nginxplus_cache_bypass_bytes{class="nginx",zone="jwks_uri_webapp"} 0

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (8a2c9a9) 52.32% compared to head (d576d0b) 52.31%.
Report is 5 commits behind head on main.

❗ Current head d576d0b differs from pull request most recent head e7ebfa5. Consider uploading reports for the commit e7ebfa5 to get more accurate results

Files	Patch %	Lines
cmd/nginx-ingress/main.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5008      +/-   ##
==========================================
- Coverage   52.32%   52.31%   -0.01%     
==========================================
  Files          61       60       -1     
  Lines       17502    17499       -3     
==========================================
- Hits         9158     9155       -3     
- Misses       8015     8016       +1     
+ Partials      329      328       -1     

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