implemnt Prometheus sink

[zirain]

this patch try to add native prometheus support instead of a statsd_exporter sidecar container.

@mattklein123 can you take a first look, I will finish the test if this's acceptable.

[mattklein123]

Sure sounds good. Please add docs also.

[SpecialYang]

With the following rate limit policy, the process will crash.

apiVersion: v1
kind: ConfigMap
metadata:
  name: ratelimit-config
data:
  config.yaml: |
    domain: ratelimit
    descriptors:
      - key: PATH
        value: "/version"
        rate_limit:
          unit: minute
          requests_per_unit: 10
        descriptors:
        - key: test
          value: true
          rate_limit:
            unit: minute
            requests_per_unit: 2

panic: inconsistent label cardinality: expected 3 label values but got 2 in []string{"ratelimit", "PATH_/version"}

goroutine 21 [running]:
github.com/prometheus/client_golang/prometheus.(*CounterVec).WithLabelValues(...)
	/go/pkg/mod/github.com/prometheus/client_golang@v1.19.1/prometheus/counter.go:284
github.com/envoyproxy/ratelimit/src/prometheusstats.(*prometheusSink).FlushCounter(0xc00013c4b0, {0xc0004c20c0?, 0xc0004ce690?}, 0x1b)
	/ratelimit/src/prometheusstats/prometheus_sink.go:122 +0x4ec
github.com/lyft/gostats.(*statStore).Flush.func1({0xd434e0?, 0xc0004dd580?}, {0xe36580?, 0xc000392d00?})
	/go/pkg/mod/github.com/lyft/gostats@v0.4.14/stats.go:386 +0x76
sync.(*Map).Range(0xc0000d36e0?, 0xc0004a7f08)
	/usr/local/go/src/sync/map.go:477 +0x1f8
github.com/lyft/gostats.(*statStore).Flush(0xc0004d6320)
	/go/pkg/mod/github.com/lyft/gostats@v0.4.14/stats.go:383 +0xbf
github.com/lyft/gostats.(*statStore).StartContext(0xc0004d6320, {0x1083980, 0x1888980}, 0xc00013d770)
	/go/pkg/mod/github.com/lyft/gostats@v0.4.14/stats.go:367 +0x35
github.com/lyft/gostats.(*statStore).Start(0x0?, 0x0?)
	/go/pkg/mod/github.com/lyft/gostats@v0.4.14/stats.go:373 +0x25
created by github.com/envoyproxy/ratelimit/src/service_cmd/runner.NewRunner in goroutine 1
	/ratelimit/src/service_cmd/runner/runner.go:77 +0x74b

[zirain]

With the following rate limit policy, the process will crash.

apiVersion: v1
kind: ConfigMap
metadata:
  name: ratelimit-config
data:
  config.yaml: |
    domain: ratelimit
    descriptors:
      - key: PATH
        value: "/version"
        rate_limit:
          unit: minute
          requests_per_unit: 10
        descriptors:
        - key: test
          value: true
          rate_limit:
            unit: minute
            requests_per_unit: 2

panic: inconsistent label cardinality: expected 3 label values but got 2 in []string{"ratelimit", "PATH_/version"}

goroutine 21 [running]:
github.com/prometheus/client_golang/prometheus.(*CounterVec).WithLabelValues(...)
	/go/pkg/mod/github.com/prometheus/client_golang@v1.19.1/prometheus/counter.go:284
github.com/envoyproxy/ratelimit/src/prometheusstats.(*prometheusSink).FlushCounter(0xc00013c4b0, {0xc0004c20c0?, 0xc0004ce690?}, 0x1b)
	/ratelimit/src/prometheusstats/prometheus_sink.go:122 +0x4ec
github.com/lyft/gostats.(*statStore).Flush.func1({0xd434e0?, 0xc0004dd580?}, {0xe36580?, 0xc000392d00?})
	/go/pkg/mod/github.com/lyft/gostats@v0.4.14/stats.go:386 +0x76
sync.(*Map).Range(0xc0000d36e0?, 0xc0004a7f08)
	/usr/local/go/src/sync/map.go:477 +0x1f8
github.com/lyft/gostats.(*statStore).Flush(0xc0004d6320)
	/go/pkg/mod/github.com/lyft/gostats@v0.4.14/stats.go:383 +0xbf
github.com/lyft/gostats.(*statStore).StartContext(0xc0004d6320, {0x1083980, 0x1888980}, 0xc00013d770)
	/go/pkg/mod/github.com/lyft/gostats@v0.4.14/stats.go:367 +0x35
github.com/lyft/gostats.(*statStore).Start(0x0?, 0x0?)
	/go/pkg/mod/github.com/lyft/gostats@v0.4.14/stats.go:373 +0x25
created by github.com/envoyproxy/ratelimit/src/service_cmd/runner.NewRunner in goroutine 1
	/ratelimit/src/service_cmd/runner/runner.go:77 +0x74b

can you share more logs?

[zirain]

@SpecialYang can you share the reproduce steps?

[zirain]

There are a lot of problems with this implementation, I'd like close this one first, and proposal a new one later.