From: Murali Parthasarathy K <srinivas.yanamadala@techmahindra.com>
Date: Wed, 9 Apr 2025 13:18:36 +0000 (+0200)
Subject: Support for Prometheus client for opa-pdp
X-Git-Tag: 1.0.5~7
X-Git-Url: https://gerrit.onap.org/r/gitweb?a=commitdiff_plain;h=0d2cb30d338b6dbd9add37130189bd16ea243f81;p=policy%2Fopa-pdp.git

Support for Prometheus client for opa-pdp

Issue-ID: POLICY-5336
Change-Id: I1438ff760b229754a2ba3380ebc51d5df465eebd
Signed-off-by: Srinivas Yanamadala <srinivas.yanamadala@techmahindra.com>
---

diff --git a/api/register-handlers.go b/api/register-handlers.go
index ab71afe..f7ec9d9 100644
--- a/api/register-handlers.go
+++ b/api/register-handlers.go
@@ -30,6 +30,9 @@ import (
 	"policy-opa-pdp/pkg/log"
 	"policy-opa-pdp/pkg/metrics"
 	"policy-opa-pdp/pkg/opasdk"
+	"time"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
 // RegisterHandlers registers the HTTP handlers for the service.
@@ -37,7 +40,7 @@ func RegisterHandlers() {
 
 	// Handler for OPA decision making
 	opaDecisionHandler := http.HandlerFunc(decision.OpaDecision)
-	http.Handle("/policy/pdpo/v1/decision", basicAuth(opaDecisionHandler))
+	http.Handle("/policy/pdpo/v1/decision", basicAuth(trackDecisionResponseTime(opaDecisionHandler)))
 
 	// Handler for kubernetes readiness probe
 	readinessProbeHandler := http.HandlerFunc(readinessProbe)
@@ -55,10 +58,32 @@ func RegisterHandlers() {
 	http.Handle("/opa/listpolicies", listPoliciesHandler)
 
 	dataHandler := http.HandlerFunc(data.DataHandler)
-	http.Handle("/policy/pdpo/v1/data/", basicAuth(dataHandler))
+	http.Handle("/policy/pdpo/v1/data/", basicAuth(trackDataResponseTime(dataHandler)))
 
-	http.Handle("/policy/pdpo/v1/data", basicAuth(dataHandler))
+	http.Handle("/policy/pdpo/v1/data", basicAuth(trackDataResponseTime(dataHandler)))
 
+	//Handler for prometheus
+	http.Handle("/metrics", promhttp.Handler())
+
+}
+
+//Track Decision response time metrics
+func trackDecisionResponseTime(next http.HandlerFunc) http.HandlerFunc {
+	return trackResponseTime(metrics.DecisionResponseTime, next)
+}
+
+//Track Data response time metrics
+func trackDataResponseTime(next http.HandlerFunc) http.HandlerFunc {
+	return trackResponseTime(metrics.DataResponseTime, next)
+}
+
+func trackResponseTime(metricCollector prometheus.Observer, next http.HandlerFunc) http.HandlerFunc {
+	return func(res http.ResponseWriter, req *http.Request) {
+		start := time.Now()
+		next(res, req)
+		duration := time.Since(start).Seconds()
+		metricCollector.Observe(duration)
+	}
 }
 
 // handles authentication
diff --git a/api/register-handlers_test.go b/api/register-handlers_test.go
index 3cbd248..2e682a0 100644
--- a/api/register-handlers_test.go
+++ b/api/register-handlers_test.go
@@ -26,6 +26,8 @@ import (
 	"policy-opa-pdp/pkg/decision"
 	"policy-opa-pdp/pkg/healthcheck"
 	"testing"
+	"time"
+	"github.com/stretchr/testify/assert"
 )
 
 // Mock configuration
@@ -112,3 +114,59 @@ func TestReadinessProbe(t *testing.T) {
 		t.Errorf("readinessProbe returned unexpected body: got %v want %v", rr.Body.String(), expected)
 	}
 }
+
+
+type mockObserver struct {
+	observedDuration float64
+}
+
+func (m *mockObserver) Observe(duration float64) {
+	m.observedDuration = duration
+}
+
+// Test trackDecisionResponseTime function
+func TestTrackDecisionResponseTime(t *testing.T) {
+	observer := &mockObserver{}
+	handler := trackDecisionResponseTime(func(res http.ResponseWriter, req *http.Request) {
+		time.Sleep(50 * time.Millisecond)
+		res.WriteHeader(http.StatusOK)
+	})
+
+	req := httptest.NewRequest("GET", "/decision", nil)
+	res := httptest.NewRecorder()
+
+	handler(res, req)
+
+	assert.NotNil(t, observer.observedDuration)
+}
+
+// Test trackDataResponseTime function
+func TestTrackDataResponseTime(t *testing.T) {
+	observer := &mockObserver{}
+	handler := trackDataResponseTime(func(res http.ResponseWriter, req *http.Request) {
+		time.Sleep(30 * time.Millisecond)
+		res.WriteHeader(http.StatusOK)
+	})
+
+	req := httptest.NewRequest("GET", "/data", nil)
+	res := httptest.NewRecorder()
+
+	handler(res, req)
+
+	assert.NotNil(t, observer.observedDuration)
+}
+
+// Test trackResponseTime function
+func TestTrackResponseTime(t *testing.T) {
+	observer := &mockObserver{}
+
+	handler := trackResponseTime(observer, func(res http.ResponseWriter, req *http.Request) {
+		time.Sleep(20 * time.Millisecond)
+		res.WriteHeader(http.StatusOK)
+	})
+
+	req := httptest.NewRequest("GET", "/response", nil)
+	res := httptest.NewRecorder()
+	handler(res, req)
+	assert.NotNil(t, observer.observedDuration)
+}
diff --git a/pkg/metrics/counters.go b/pkg/metrics/counters.go
index 09ff4f7..b2b03d8 100644
--- a/pkg/metrics/counters.go
+++ b/pkg/metrics/counters.go
@@ -19,8 +19,10 @@
 
 package metrics
 
-import "sync"
-
+import (
+        "sync"
+        "github.com/prometheus/client_golang/prometheus"
+)
 // global counter variables
 var TotalErrorCount int64
 var DecisionSuccessCount int64
@@ -32,6 +34,24 @@ var UndeploySuccessCount int64
 var TotalPoliciesCount int64
 var mu sync.Mutex
 
+//Decision and Data counters to be used in prometheus
+var (
+	DecisionResponseTime = prometheus.NewSummary(prometheus.SummaryOpts{
+		Name:    "opa_decision_response_time_seconds",
+		Help:    "Response time of OPA decision handler",
+	})
+	DataResponseTime = prometheus.NewSummary(prometheus.SummaryOpts{
+		Name:    "opa_data_response_time_seconds",
+		Help:    "Response time of OPA data handler",
+	})
+)
+
+//register counters in init
+func init() {
+	prometheus.MustRegister(DecisionResponseTime)
+	prometheus.MustRegister(DataResponseTime)
+}
+
 // Increment counter
 func IncrementTotalErrorCount() {
 	mu.Lock()