Merge branch 'feature/gb/add-serveress-metrics' into 'master'

Add serverless serving metrics

Closes #346

See merge request gitlab-org/gitlab-pages!231

4 files changed, 25 insertions, 1 deletions

diff --git a/acceptance_test.go b/acceptance_test.go
index aec7195c..4e773566 100644
--- a/acceptance_test.go
+++ b/acceptance_test.go
@@ -403,6 +403,8 @@ func TestPrometheusMetricsCanBeScraped(t *testing.T) {
 	require.Contains(t, string(body), "gitlab_pages_domains_configuration_update_duration gauge")
 	require.Contains(t, string(body), "gitlab_pages_domains_source_cache_hit 0")
 	require.Contains(t, string(body), "gitlab_pages_domains_source_cache_miss 0")
+	require.Contains(t, string(body), "gitlab_pages_serverless_requests 0")
+	require.Contains(t, string(body), "gitlab_pages_serverless_latency_sum 0")
 }
 
 func TestStatusPage(t *testing.T) {
diff --git a/internal/serving/serverless/serverless.go b/internal/serving/serverless/serverless.go
index a8d090da..a73affeb 100644
--- a/internal/serving/serverless/serverless.go
+++ b/internal/serving/serverless/serverless.go
@@ -5,6 +5,7 @@ import (
 
 	"gitlab.com/gitlab-org/gitlab-pages/internal/httperrors"
 	"gitlab.com/gitlab-org/gitlab-pages/internal/serving"
+	"gitlab.com/gitlab-org/gitlab-pages/metrics"
 )
 
 // Serverless is a servering used to proxy requests between a client and
@@ -26,6 +27,8 @@ func New(function Function, cluster Cluster) serving.Serving {
 
 // ServeFileHTTP handle an incoming request and proxies it to Knative cluster
 func (s *Serverless) ServeFileHTTP(h serving.Handler) bool {
+	metrics.ServerlessRequests.Inc()
+
 	s.proxy.ServeHTTP(h.Writer, h.Request)
 
 	return true
diff --git a/internal/serving/serverless/transport.go b/internal/serving/serverless/transport.go
index 5a0f5165..b7fabb13 100644
--- a/internal/serving/serverless/transport.go
+++ b/internal/serving/serverless/transport.go
@@ -5,6 +5,8 @@ import (
 	"net"
 	"net/http"
 	"time"
+
+	"gitlab.com/gitlab-org/gitlab-pages/metrics"
 )
 
 // Transport is a struct that handle the proxy connection round trip to Knative
@@ -39,8 +41,11 @@ func NewTransport(cluster Cluster) *Transport {
 
 // RoundTrip performs a connection to a Knative cluster and returns a response
 func (t *Transport) RoundTrip(request *http.Request) (*http.Response, error) {
+	start := time.Now()
+
 	response, err := t.transport.RoundTrip(request)
 
-	// TODO add prometheus metrics for round trip timing
+	metrics.ServerlessLatency.Observe(time.Since(start).Seconds())
+
 	return response, err
 }
diff --git a/metrics/metrics.go b/metrics/metrics.go
index b858e229..1ae527a8 100644
--- a/metrics/metrics.go
+++ b/metrics/metrics.go
@@ -46,6 +46,18 @@ var (
 		Name: "gitlab_pages_domains_source_cache_miss",
 		Help: "The number of GitLab domains API cache misses",
 	})
+
+	// ServerlessRequests measures the amount of serverless invocations
+	ServerlessRequests = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "gitlab_pages_serverless_requests",
+		Help: "The number of total GitLab Serverless requests served",
+	})
+
+	// ServerlessLatency records serverless serving roundtrip duration
+	ServerlessLatency = prometheus.NewHistogram(prometheus.HistogramOpts{
+		Name: "gitlab_pages_serverless_latency",
+		Help: "Serverless serving roundtrip duration",
+	})
 )
 
 func init() {
@@ -56,4 +68,6 @@ func init() {
 	prometheus.MustRegister(DomainsConfigurationUpdateDuration)
 	prometheus.MustRegister(DomainsSourceCacheHit)
 	prometheus.MustRegister(DomainsSourceCacheMiss)
+	prometheus.MustRegister(ServerlessRequests)
+	prometheus.MustRegister(ServerlessLatency)
 }