Merged in bugfix/dynamic-test-ports (pull request #70)

use dynamic ports for prometheus tests

* dynamic port

* Merge branch 'main' of bitbucket.org:aarete/query-orchestration into bugfix/dynamic-test-ports


Approved-by: Michael McGuinness

internal/serviceconfig/observability/prometheus/prometheus_test.go

@@ -4,23 +4,46 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"net"
 	"net/http"
 	"strings"
 	"testing"
 	"time"
 )
 
+func GetFreePortForTesting() (int, error) {
+	// Create a TCP listener on port 0 (lets OS choose a free port)
+	addr, err := net.ResolveTCPAddr("tcp", "localhost:0")
+	if err != nil {
+		return 0, fmt.Errorf("failed to resolve TCP address: %v", err)
+	}
+
+	l, err := net.ListenTCP("tcp", addr)
+	if err != nil {
+		return 0, fmt.Errorf("failed to create TCP listener: %v", err)
+	}
+	defer l.Close()
+
+	// Get the port that was assigned by the OS
+	return l.Addr().(*net.TCPAddr).Port, nil
+}
+
 func TestMetricsIntegration(t *testing.T) {
 	// Create a context with cancellation for the test
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
+	testingPort, errorGettingPort := GetFreePortForTesting()
+	if errorGettingPort != nil {
+		t.Fatalf("Failed to get a free port for testing: %v", errorGettingPort)
+	}
+
 	// Step 1: Define our test metrics configuration
 	config := MetricsConfig{
 		Namespace: "test",
 		Subsystem: "metrics",
-		Port:      9090, // Using 9090 for tests
-		ServeHttp: true, // Enable the built-in HTTP server
+		Port:      testingPort, // Using 9090 for tests
+		ServeHttp: true,        // Enable the built-in HTTP server
 		Definitions: []MetricDefinition{
 			{
 				// Counter example: counting total events
@@ -114,7 +137,8 @@ func TestMetricsIntegration(t *testing.T) {
 	time.Sleep(time.Second)
 
 	// Step 5: Fetch metrics from the HTTP endpoint
-	resp, err := http.Get("http://localhost:9090/metrics")
+	URLForMetrics := fmt.Sprintf("http://localhost:%d/metrics", testingPort)
+	resp, err := http.Get(URLForMetrics)
 	if err != nil {
 		t.Fatalf("Failed to fetch metrics: %v", err)
 	}
@@ -155,10 +179,15 @@ func TestMetricsIntegration(t *testing.T) {
 	// Test cancellation
 	t.Run("Context cancellation", func(t *testing.T) {
 		// Create a new metrics instance with a separate context
+		testingPort, errorGettingPort := GetFreePortForTesting()
+		if errorGettingPort != nil {
+			t.Fatalf("Failed to get a free port for testing: %v", errorGettingPort)
+		}
+
 		cancelCtx, cancelFunc := context.WithCancel(context.Background())
 		_, err := New(cancelCtx, MetricsConfig{
 			Namespace: "test_cancel",
-			Port:      9091,
+			Port:      testingPort,
 			ServeHttp: true,
 		})
 		if err != nil {
@@ -173,7 +202,8 @@ func TestMetricsIntegration(t *testing.T) {
 
 		// Try to connect to the server - it should fail after a short delay
 		time.Sleep(time.Second)
-		_, err = http.Get("http://localhost:9091/metrics")
+		testingUrl := fmt.Sprintf("http://localhost:%d/metrics", testingPort)
+		_, err = http.Get(testingUrl)
 		if err == nil {
 			t.Error("Expected server to be shutdown after context cancellation")
 		}