nginx-metrics: expose status codes metrics

[markoburcul]

Combine connections metrics from stub_status and create status codes metrics. Expose everything under /metrics endpoint of eth-rpc-proxy. Remove the prometheus nginx metrics exporter since it is replaced.

Example of metrics scraped from /metrics endpoint:

# HELP nginx_connections_accepted Accepted client connections
# TYPE nginx_connections_accepted counter
nginx_connections_accepted 9
# HELP nginx_connections_active Active client connections
# TYPE nginx_connections_active gauge
nginx_connections_active 2
# HELP nginx_connections_handled Handled client connections
# TYPE nginx_connections_handled counter
nginx_connections_handled 9
# HELP nginx_connections_reading Connections where NGINX is reading the request header
# TYPE nginx_connections_reading gauge
nginx_connections_reading 0
# HELP nginx_connections_waiting Idle client connections
# TYPE nginx_connections_waiting gauge
nginx_connections_waiting 1
# HELP nginx_connections_writing Connections where NGINX is writing the response back to the client
# TYPE nginx_connections_writing gauge
nginx_connections_writing 1
# HELP nginx_http_requests_total Total http requests
# TYPE nginx_http_requests_total counter
nginx_http_requests_total 9
# HELP nginx_http_requests_by_status HTTP requests by status code class
# TYPE nginx_http_requests_by_status counter
nginx_http_requests_by_status{status="2xx"} 6
nginx_http_requests_by_status{status="3xx"} 0
nginx_http_requests_by_status{status="4xx"} 1
nginx_http_requests_by_status{status="5xx"} 1
# HELP nginx_up Status of the last metric scrape
# TYPE nginx_up gauge
nginx_up 1

[friofry]

Looks good!

[jakubgs]

It's true, nginx-prometheus-exporter is very limited in what it provides.