Add metrics for API calls

cmd/application-load-balancer-controller/main.go

@@ -5,11 +5,13 @@ import (
 	"os"
 
 	"github.com/stackitcloud/application-load-balancer-controller/pkg/controller/ingress"
+	"github.com/stackitcloud/application-load-balancer-controller/pkg/metrics"
 	albclient "github.com/stackitcloud/application-load-balancer-controller/pkg/stackit"
 	stackitconfig "github.com/stackitcloud/application-load-balancer-controller/pkg/stackit/config"
 	sdkconfig "github.com/stackitcloud/stackit-sdk-go/core/config"
 	albsdk "github.com/stackitcloud/stackit-sdk-go/services/alb/v2api"
 	certsdk "github.com/stackitcloud/stackit-sdk-go/services/certificates/v2api"
+	ctrlmetrics "sigs.k8s.io/controller-runtime/pkg/metrics"
 
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
 	ctrl "sigs.k8s.io/controller-runtime"
@@ -32,6 +34,10 @@ type options struct {
 	cloudConfig             string
 }
 
+func init() {
+	ctrlmetrics.Registry.MustRegister(metrics.NewExporter())
+}
+
 // nolint:funlen // This function isn't awfully complex.
 func main() {
 	var opts options
@@ -75,13 +81,15 @@ func main() {
 	}
 	albOpts := []sdkconfig.ConfigurationOption{
 		sdkconfig.WithUserAgent("application-load-balancer-controller"),
+		sdkconfig.WithHTTPClient(metrics.NewHTTPClient("application-load-balancer-controller")),
 	}
 	if config.Global.APIEndpoints.ApplicationLoadBalancerAPI != "" {
 		albOpts = append(albOpts, sdkconfig.WithEndpoint(config.Global.APIEndpoints.ApplicationLoadBalancerAPI))
 	}
 
 	certOpts := []sdkconfig.ConfigurationOption{
 		sdkconfig.WithUserAgent("application-load-balancer-controller"),
+		sdkconfig.WithHTTPClient(metrics.NewHTTPClient("application-load-balancer-controller")),
 	}
 	if config.Global.APIEndpoints.ApplicationLoadBalancerCertificateAPI != "" {
 		certOpts = append(certOpts, sdkconfig.WithEndpoint(config.Global.APIEndpoints.ApplicationLoadBalancerCertificateAPI))

go.mod

@@ -6,6 +6,8 @@ require (
 	github.com/google/uuid v1.6.0
 	github.com/onsi/ginkgo/v2 v2.32.1
 	github.com/onsi/gomega v1.42.1
+	github.com/prometheus/client_golang v1.23.2
+	github.com/prometheus/client_model v0.6.2
 	github.com/stackitcloud/stackit-sdk-go/core v0.26.0
 	github.com/stackitcloud/stackit-sdk-go/services/alb v0.17.1
 	github.com/stackitcloud/stackit-sdk-go/services/certificates v1.9.1
@@ -38,13 +40,12 @@ require (
 	github.com/google/pprof v0.0.0-20260402051712-545e8a4df936 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/kylelemons/godebug v1.1.0 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
-	github.com/prometheus/client_golang v1.23.2 // indirect
-	github.com/prometheus/client_model v0.6.2 // indirect
 	github.com/prometheus/common v0.67.5 // indirect
 	github.com/prometheus/procfs v0.19.2 // indirect
 	github.com/spf13/pflag v1.0.9 // indirect

pkg/metrics/http.go

@@ -0,0 +1,128 @@
+package metrics
+
+import (
+	"net/http"
+	"runtime"
+	"strconv"
+	"strings"
+	"time"
+	"unicode"
+	"unicode/utf8"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const UnknownOperation = "UnknownOperation"
+
+func NewHTTPClient(componentName string) *http.Client {
+	return WrapHTTPClient(http.DefaultClient, componentName)
+}
+
+func WrapHTTPClient(client *http.Client, componentName string) *http.Client {
+	if client == nil {
+		return nil
+	}
+	wrappedClient := *client
+
+	baseTransport := client.Transport
+	if baseTransport == nil {
+		baseTransport = http.DefaultTransport
+	}
+
+	// Chain your instrumented round tripper
+	wrappedClient.Transport = &InstrumentedRoundTripper{
+		base:          baseTransport,
+		componentName: componentName,
+	}
+
+	return &wrappedClient
+}
+
+type InstrumentedRoundTripper struct {
+	base          http.RoundTripper
+	componentName string
+}
+
+func (rt *InstrumentedRoundTripper) RoundTrip(request *http.Request) (*http.Response, error) {
+	startTime := time.Now()
+	response, err := rt.base.RoundTrip(request)
+	duration := time.Since(startTime)
+
+	statusCode := "network_error"
+	if response != nil {
+		statusCode = strconv.Itoa(response.StatusCode)
+	}
+
+	// request.Host is optional so we can fallback to request.URL.Host (if available)
+	host := request.Host
+	if host == "" && request.URL != nil {
+		host = request.URL.Host
+	}
+
+	labels := prometheus.Labels{
+		componentLabel: rt.componentName,
+		hostLabel:      host,
+		methodLabel:    request.Method,
+		operationLabel: getSDKOperationName(),
+		codeLabel:      statusCode,
+	}
+
+	HTTPRequestDurationHistogram.With(labels).Observe(duration.Seconds())
+	HTTPRequestCount.With(labels).Inc()
+
+	isHTTPError := response != nil && response.StatusCode >= 400
+	isNetworkError := err != nil
+
+	if isHTTPError || isNetworkError {
+		HTTPErrorCount.With(labels).Inc()
+	}
+
+	return response, err
+}
+
+// getSDKOperationName returns the name of the STACKIT SDK function. To do this the function gets the last 10 callers and checks
+// for functions from the stackitcloud/stackit-sdk-go. It fall back to UnknownOperation if no function was found.
+func getSDKOperationName() string {
+	pc := make([]uintptr, 10)
+
+	// Skip 3 because the first 3 are always Callers, getSDKOperationName, RoundTrip.
+	n := runtime.Callers(3, pc)
+	if n == 0 {
+		return UnknownOperation
+	}
+
+	frames := runtime.CallersFrames(pc[:n])
+	moreFrames := true
+	for moreFrames {
+		var frame runtime.Frame
+		frame, moreFrames = frames.Next()
+
+		if !strings.Contains(frame.Function, "stackitcloud/stackit-sdk-go") {
+			continue
+		}
+
+		parts := strings.Split(frame.Function, ".")
+		if len(parts) > 0 {
+			funcName := parts[len(parts)-1]
+
+			// Skip function names with 0 len
+			// Skip Execute, because there is a function with more detailed name
+			// Skip RoundTrip, because this only the RoundTrip for the AuthFlow
+			if funcName == "" ||
+				funcName == "Execute" ||
+				funcName == "RoundTrip" {
+				continue
+			}
+
+			// Skip Private functions
+			r, _ := utf8.DecodeRuneInString(funcName)
+			if !unicode.IsUpper(r) {
+				continue
+			}
+
+			return strings.TrimSuffix(funcName, "Execute")
+		}
+	}
+
+	return UnknownOperation
+}