fn: stats view/distribution improvements (#1154)

* fn: stats view/distribution improvements

*) View latency distribution is now an argument
in view creation functions. This allows easier
override to set custom buckets. It is simplistic
and assumes all latency views would use the same
set, but in practice this is already the case.
*) Removed API view creation to main, this should not
be enabled for all node types. This is consistent with
the rest of the system.

* fn: Docker samples of cpu/mem/disk with specific buckets

api/server/gin_middlewares.go

@@ -79,6 +79,19 @@ func traceWrap(c *gin.Context) {
 }
 
 func apiMetricsWrap(s *Server) {
+	pathKey, err := tag.NewKey("path")
+	if err != nil {
+		logrus.Fatal(err)
+	}
+	methodKey, err := tag.NewKey("method")
+	if err != nil {
+		logrus.Fatal(err)
+	}
+	statusKey, err := tag.NewKey("status")
+	if err != nil {
+		logrus.Fatal(err)
+	}
+
 	measure := func(engine *gin.Engine) func(*gin.Context) {
 		var routes gin.RoutesInfo
 		return func(c *gin.Context) {
@@ -102,7 +115,7 @@ func apiMetricsWrap(s *Server) {
 			if err != nil {
 				logrus.Fatal(err)
 			}
-			stats.Record(ctx, apiRequestCount.M(1))
+			stats.Record(ctx, apiRequestCountMeasure.M(1))
 			c.Next()
 
 			status := strconv.Itoa(c.Writer.Status())
@@ -112,7 +125,7 @@ func apiMetricsWrap(s *Server) {
 			if err != nil {
 				logrus.Fatal(err)
 			}
-			stats.Record(ctx, apiLatency.M(float64(time.Since(start))/float64(time.Millisecond)))
+			stats.Record(ctx, apiLatencyMeasure.M(int64(time.Since(start)/time.Millisecond)))
 		}
 	}
 

api/server/server.go

@@ -600,10 +600,6 @@ func WithAgentFromEnv() Option {
 				placer = pool.NewNaivePlacer(&placerCfg)
 			}
 
-			keys := []string{"fn_appname", "fn_path"}
-			pool.RegisterPlacerViews(keys)
-			agent.RegisterLBAgentViews(keys)
-
 			s.lbReadAccess = agent.NewCachedDataAccess(cl)
 			s.agent, err = agent.NewLBAgent(cl, runnerPool, placer)
 			if err != nil {
@@ -758,7 +754,7 @@ func WithPrometheus() Option {
 		}
 		s.promExporter = exporter
 		view.RegisterExporter(exporter)
-		registerViews()
+
 		return nil
 	}
 }

api/server/stats.go

@@ -1,68 +1,26 @@
 package server
 
 import (
+	"github.com/fnproject/fn/api/common"
+
 	"github.com/sirupsen/logrus"
 	"go.opencensus.io/stats"
 	"go.opencensus.io/stats/view"
-	"go.opencensus.io/tag"
 )
 
 var (
-	apiRequestCount = stats.Int64("api/request_count", "Number of API requests", stats.UnitDimensionless)
-	apiLatency      = stats.Float64("api/latency", "API latency", stats.UnitMilliseconds)
+	apiRequestCountMeasure  = common.MakeMeasure("api/request_count", "Count of API requests started", stats.UnitDimensionless)
+	apiResponseCountMeasure = common.MakeMeasure("api/response_count", "API response count", stats.UnitDimensionless)
+	apiLatencyMeasure       = common.MakeMeasure("api/latency", "Latency distribution of API requests", stats.UnitMilliseconds)
 )
 
-var (
-	pathKey   = makeKey("path")
-	methodKey = makeKey("method")
-	statusKey = makeKey("status")
-)
-
-var (
-	defaultLatencyDistribution = view.Distribution(0, 1, 2, 3, 4, 5, 6, 8, 10, 13, 16, 20, 25, 30, 40, 50, 65, 80, 100, 130, 160, 200, 250, 300, 400, 500, 650, 800, 1000, 2000, 5000, 10000, 20000, 50000, 100000)
-)
-
-var (
-	apiRequestCountView = &view.View{
-		Name:        "api/request_count",
-		Description: "Count of API requests started",
-		Measure:     apiRequestCount,
-		TagKeys:     []tag.Key{pathKey, methodKey},
-		Aggregation: view.Count(),
-	}
-
-	apiResponseCountView = &view.View{
-		Name:        "api/response_count",
-		Description: "API response count",
-		TagKeys:     []tag.Key{pathKey, methodKey, statusKey},
-		Measure:     apiLatency,
-		Aggregation: view.Count(),
-	}
-
-	apiLatencyView = &view.View{
-		Name:        "api/latency",
-		Description: "Latency distribution of API requests",
-		Measure:     apiLatency,
-		TagKeys:     []tag.Key{pathKey, methodKey, statusKey},
-		Aggregation: defaultLatencyDistribution,
-	}
-)
-
-func registerViews() {
+func RegisterAPIViews(tagKeys []string, dist []float64) {
 	err := view.Register(
-		apiRequestCountView,
-		apiResponseCountView,
-		apiLatencyView,
+		common.CreateView(apiRequestCountMeasure, view.Count(), tagKeys),
+		common.CreateView(apiResponseCountMeasure, view.Count(), tagKeys),
+		common.CreateView(apiLatencyMeasure, view.Distribution(dist...), tagKeys),
 	)
 	if err != nil {
 		logrus.WithError(err).Fatal("cannot register view")
 	}
 }
-
-func makeKey(name string) tag.Key {
-	key, err := tag.NewKey(name)
-	if err != nil {
-		logrus.Fatal(err)
-	}
-	return key
-}