Merge pull request #3 from nais/metrics

Metrics and dashboard

pkg/metrics/metrics.go

@@ -1,11 +1,44 @@
 package metrics
 
 import (
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"net/http"
+	"time"
+)
+
+const (
+	Namespace = "wonderwall"
+
+	RedisOperationLabel = "operation"
+)
+
+var (
+	RedisLatency = prometheus.NewHistogramVec(prometheus.HistogramOpts{
+		Name:      "redis_latency",
+		Namespace: Namespace,
+		Help:      "latency in redis operations",
+		Buckets:   prometheus.ExponentialBuckets(0.02, 2, 14),
+	}, []string{RedisOperationLabel})
 )
 
 func Handle(address string) error {
 	handler := promhttp.Handler()
 	return http.ListenAndServe(address, handler)
 }
+
+func Register(registry prometheus.Registerer) {
+	registry.MustRegister(
+		RedisLatency,
+	)
+}
+
+func ObserveRedisLatency(operation string, fun func() error) error {
+	timer := time.Now()
+	err := fun()
+	used := time.Now().Sub(timer)
+	RedisLatency.With(prometheus.Labels{
+		RedisOperationLabel: operation,
+	}).Observe(used.Seconds())
+	return err
+}

pkg/session/redis.go

@@ -3,6 +3,7 @@ package session
 import (
 	"context"
 	"github.com/go-redis/redis/v8"
+	"github.com/nais/wonderwall/pkg/metrics"
 	"time"
 )
 
@@ -20,8 +21,12 @@ func NewRedis(client redis.Cmdable) Store {
 
 func (s *redisSessionStore) Read(ctx context.Context, key string) (*Data, error) {
 	data := &Data{}
-	status := s.client.Get(ctx, key)
-	err := status.Scan(data)
+	err := metrics.ObserveRedisLatency("Read", func() error {
+		var err error
+		status := s.client.Get(ctx, key)
+		err = status.Scan(data)
+		return err
+	})
 	if err != nil {
 		return nil, err
 	}
@@ -29,11 +34,15 @@ func (s *redisSessionStore) Read(ctx context.Context, key string) (*Data, error)
 }
 
 func (s *redisSessionStore) Write(ctx context.Context, key string, value *Data, expiration time.Duration) error {
-	status := s.client.Set(ctx, key, value, expiration)
-	return status.Err()
+	return metrics.ObserveRedisLatency("Write", func() error {
+		status := s.client.Set(ctx, key, value, expiration)
+		return status.Err()
+	})
 }
 
 func (s *redisSessionStore) Delete(ctx context.Context, keys ...string) error {
-	status := s.client.Del(ctx, keys...)
-	return status.Err()
+	return metrics.ObserveRedisLatency("Delete", func() error {
+		status := s.client.Del(ctx, keys...)
+		return status.Err()
+	})
 }