[SWIP-8] Support Kong monitoring

[CodePrometheus]

Support Kong Monitoring

Motivation

Kong or Kong API Gateway is a cloud-native, platform-agnostic, scalable API Gateway
distinguished for its high performance and extensibility via plugins. Now I want to add Kong monitoring via the OpenTelemetry Collector,
which fetches metrics from it's own HTTP endpoint to expose metrics data for Prometheus.

Architecture Graph

There is no significant architecture-level change.

Proposed Changes

1. Kong expose its own metrics via HTTP endpoint to opentelemetry collector, OpenTelemetry Collector fetches metrics from it and pushes metrics to SkyWalking OTEL Receiver via OpenTelemetry exporter.
2. The SkyWalking OAP Server parses the expression with MAL to filter/calculate/aggregate and store the results.
3. These metrics can be displayed via the SkyWalking UI, and the metrics can be customized for display on the UI dashboard.

Kong Request Supported Metrics

Monitoring Panel	Unit	Metric Name	Description	Data Source
Bandwidth	bytes	meter_kong_service_http_bandwidth meter_kong_instance_http_bandwidth meter_kong_endpoint_http_bandwidth	Total bandwidth (ingress/egress) throughput	Kong
HTTP Status	count	meter_kong_service_http_status meter_kong_instance_http_status meter_kong_endpoint_http_status	HTTP status codes per consumer/service/route in Kong	Kong
HTTP Request	count	meter_kong_service_http_requests meter_kong_instance_http_requests	Total number of requests	Kong

Kong Database Supported Metrics

Monitoring Panel	Unit	Metric Name	Description	Data Source
DB	count	meter_kong_service_datastore_reachable meter_kong_instance_datastore_reachable	Datastore reachable from Kong	Kong
DB	bytes	meter_kong_instance_shared_dict_bytes	Allocated slabs in bytes in a shared_dict	Kong
DB	bytes	meter_kong_instance_shared_dict_total_bytes	Total capacity in bytes of a shared_dict	Kong
DB	bytes	meter_kong_instance_memory_workers_lua_vms_bytes	Allocated bytes in worker Lua VM	Kong

Kong Latencies Supported Metrics

Monitoring Panel	Unit	Metric Name	Description	Data Source
Latency	ms	meter_kong_service_kong_latency meter_kong_instance_kong_latency meter_kong_endpoint_kong_latency	Latency added by Kong and enabled plugins for each service/route in Kong	Kong
Latency	ms	meter_kong_service_request_latency meter_kong_instance_request_latency meter_kong_endpoint_request_latency	Total latency incurred during requests for each service/route in Kong	Kong
Latency	ms	meter_kong_service_upstream_latency meter_kong_instance_upstream_latency meter_kong_endpoint_upstream_latency	Latency added by upstream response for each service/route in Kong	Kong

Kong Nginx Supported Metrics

Monitoring Panel	Unit	Metric Name	Description	Data Source
Nginx	count	meter_kong_service_nginx_metric_errors_total	Number of nginx-lua-prometheus errors	Kong
Nginx	count	meter_kong_service_nginx_connections_total meter_kong_instance_nginx_connections_total	Number of connections by subsystem	Kong
Nginx	count	meter_kong_service_nginx_timers meter_kong_instance_nginx_timers	Number of Nginx timers	Kong

Imported Dependencies libs and their licenses.

No new dependency.

Compatibility

no breaking changes.

General usage docs

[wu-sheng]

I think we are good to have this.

[wu-sheng]

You could update the next swip ID first, and merge the swip-8 doc later with the feature.

[wu-sheng]

@CodePrometheus We are going to release 10.1 just before the National Day or after that holiday. Could you share are you going to add this into 10.1 or later?

[CodePrometheus]

I really hope it will be 10.1, but at the current pace, it's highly likely that I won't be able to catch up before the holiday.

[wu-sheng]

Thanks for the update. We will see whether we are possible to get there. There is one more feature of BanyanDB 0.7 integration.

[CodePrometheus]

As the feature progressed, I find that the metrics in the first version could has a better way of handling and categorized, I will make some adjustments to the SWIP and submit a PR when I'm ready.

[wu-sheng]

OK. Take your time. I will initial the 10.1 release before Oct 1st, I think. You could put this in 10.2.

[wu-sheng]

From what I saw from your screenshot, I would like to ask, would you have route rule metrics? I could set them as endpoint.

[CodePrometheus]

Yes, I divide them into service (cluster), instance and endpoint (route).