Added Prometheus metrics, don't forget to restrict access on /metrics endpoint.

2019-05-17 17:12:27 +02:00
parent e794311eb8
commit d5573e7f39
4 changed files with 222 additions and 4 deletions
@@ -0,0 +1,143 @@
+package instrumentation
+
+import (
+	"context"
+	"time"
+
+	"github.com/99designs/gqlgen/graphql"
+	prometheusclient "github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+	existStatusFailure = "failure"
+	exitStatusSuccess  = "success"
+)
+
+var (
+	requestStartedCounter    prometheusclient.Counter
+	requestCompletedCounter  prometheusclient.Counter
+	resolverStartedCounter   *prometheusclient.CounterVec
+	resolverCompletedCounter *prometheusclient.CounterVec
+	timeToResolveField       *prometheusclient.HistogramVec
+	timeToHandleRequest      *prometheusclient.HistogramVec
+)
+
+// Register registers the prometheus metrics.
+func Register() {
+	requestStartedCounter = prometheusclient.NewCounter(
+		prometheusclient.CounterOpts{
+			Name: "graphql_request_started_total",
+			Help: "Total number of requests started on the graphql server.",
+		},
+	)
+
+	requestCompletedCounter = prometheusclient.NewCounter(
+		prometheusclient.CounterOpts{
+			Name: "graphql_request_completed_total",
+			Help: "Total number of requests completed on the graphql server.",
+		},
+	)
+
+	resolverStartedCounter = prometheusclient.NewCounterVec(
+		prometheusclient.CounterOpts{
+			Name: "graphql_resolver_started_total",
+			Help: "Total number of resolver started on the graphql server.",
+		},
+		[]string{"object", "field"},
+	)
+
+	resolverCompletedCounter = prometheusclient.NewCounterVec(
+		prometheusclient.CounterOpts{
+			Name: "graphql_resolver_completed_total",
+			Help: "Total number of resolver completed on the graphql server.",
+		},
+		[]string{"object", "field"},
+	)
+
+	timeToResolveField = prometheusclient.NewHistogramVec(prometheusclient.HistogramOpts{
+		Name:    "graphql_resolver_duration_ms",
+		Help:    "The time taken to resolve a field by graphql server.",
+		Buckets: prometheusclient.ExponentialBuckets(1, 2, 11),
+	}, []string{"exitStatus"})
+
+	timeToHandleRequest = prometheusclient.NewHistogramVec(prometheusclient.HistogramOpts{
+		Name:    "graphql_request_duration_ms",
+		Help:    "The time taken to handle a request by graphql server.",
+		Buckets: prometheusclient.ExponentialBuckets(1, 2, 11),
+	}, []string{"exitStatus"})
+
+	prometheusclient.MustRegister(
+		requestStartedCounter,
+		requestCompletedCounter,
+		resolverStartedCounter,
+		resolverCompletedCounter,
+		timeToResolveField,
+		timeToHandleRequest,
+	)
+}
+
+// UnRegister unregisters
+func UnRegister() {
+	prometheusclient.Unregister(requestStartedCounter)
+	prometheusclient.Unregister(requestCompletedCounter)
+	prometheusclient.Unregister(resolverStartedCounter)
+	prometheusclient.Unregister(resolverCompletedCounter)
+	prometheusclient.Unregister(timeToResolveField)
+	prometheusclient.Unregister(timeToHandleRequest)
+}
+
+// ResolverMiddleware is a resolver middleware that logs metrics for prometheus.
+func ResolverMiddleware() graphql.FieldMiddleware {
+	return func(ctx context.Context, next graphql.Resolver) (interface{}, error) {
+		rctx := graphql.GetResolverContext(ctx)
+
+		resolverStartedCounter.WithLabelValues(rctx.Object, rctx.Field.Name).Inc()
+
+		observerStart := time.Now()
+
+		res, err := next(ctx)
+
+		var exitStatus string
+		if err != nil {
+			exitStatus = existStatusFailure
+		} else {
+			exitStatus = exitStatusSuccess
+		}
+
+		timeToResolveField.With(prometheusclient.Labels{"exitStatus": exitStatus}).
+			Observe(float64(time.Since(observerStart).Nanoseconds() / int64(time.Millisecond)))
+
+		resolverCompletedCounter.WithLabelValues(rctx.Object, rctx.Field.Name).Inc()
+
+		return res, err
+	}
+}
+
+// RequestMiddleware is a request middleware that logs metrics for prometheus.
+func RequestMiddleware() graphql.RequestMiddleware {
+	return func(ctx context.Context, next func(ctx context.Context) []byte) []byte {
+		requestStartedCounter.Inc()
+
+		observerStart := time.Now()
+
+		res := next(ctx)
+
+		rctx := graphql.GetResolverContext(ctx)
+		reqCtx := graphql.GetRequestContext(ctx)
+		errList := reqCtx.GetErrors(rctx)
+
+		var exitStatus string
+		if len(errList) > 0 {
+			exitStatus = existStatusFailure
+		} else {
+			exitStatus = exitStatusSuccess
+		}
+
+		timeToHandleRequest.With(prometheusclient.Labels{"exitStatus": exitStatus}).
+			Observe(float64(time.Since(observerStart).Nanoseconds() / int64(time.Millisecond)))
+
+		requestCompletedCounter.Inc()
+
+		return res
+	}
+}