Add query parameters in prometheus scaler

CHANGELOG.md

@@ -50,6 +50,7 @@ To learn more about active deprecations, we recommend checking [GitHub Discussio
 
 ### New
 
+- **General**: Add parameter queryParameters in prometheus-scaler ([#4962](https://github.com/kedacore/keda/issues/4962))
 - **General**: TODO ([#XXX](https://github.com/kedacore/keda/issues/XXX))
 
 #### Experimental

pkg/scalers/prometheus_scaler.go

@@ -10,6 +10,7 @@ import (
 	"net/http"
 	url_pkg "net/url"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/go-logr/logr"
@@ -25,6 +26,7 @@ import (
 const (
 	promServerAddress       = "serverAddress"
 	promQuery               = "query"
+	promQueryParameters     = "queryParameters"
 	promThreshold           = "threshold"
 	promActivationThreshold = "activationThreshold"
 	promNamespace           = "namespace"
@@ -48,6 +50,7 @@ type prometheusScaler struct {
 type prometheusMetadata struct {
 	serverAddress       string
 	query               string
+	queryParameters     map[string]string
 	threshold           float64
 	activationThreshold float64
 	prometheusAuth      *authentication.AuthMeta
@@ -151,6 +154,15 @@ func parsePrometheusMetadata(config *ScalerConfig) (meta *prometheusMetadata, er
 		return nil, fmt.Errorf("no %s given", promQuery)
 	}
 
+	if val, ok := config.TriggerMetadata[promQueryParameters]; ok && val != "" {
+		queryParameters, err := kedautil.ParseStringList(val)
+		if err != nil {
+			return nil, fmt.Errorf("error parsing %s: %w", promQueryParameters, err)
+		}
+
+		meta.queryParameters = queryParameters
+	}
+
 	if val, ok := config.TriggerMetadata[promThreshold]; ok && val != "" {
 		t, err := strconv.ParseFloat(val, 64)
 		if err != nil {
@@ -266,6 +278,14 @@ func (s *prometheusScaler) ExecutePromQuery(ctx context.Context) (float64, error
 		url = fmt.Sprintf("%s&namespace=%s", url, s.metadata.namespace)
 	}
 
+	for queryParameterKey, queryParameterValue := range s.metadata.queryParameters {
+		test := queryParameterValue[len(queryParameterValue)-1:]
+		if test == "?" || test == "&" {
+			queryParameterValue = strings.TrimSuffix(queryParameterValue, test)
+		}
+		url = fmt.Sprintf("%s&%s=%s", url, queryParameterKey, queryParameterValue)
+	}
+
 	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
 	if err != nil {
 		return -1, err

pkg/scalers/prometheus_scaler_test.go

@@ -10,6 +10,7 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/go-logr/logr"
 	"github.com/stretchr/testify/assert"
@@ -60,6 +61,10 @@ var testPromMetadata = []parsePrometheusMetadataTestData{
 	{map[string]string{"serverAddress": "http://localhost:9090", "metricName": "http_requests_total", "threshold": "100", "query": "up", "customHeaders": "key1=value1,key2"}, true},
 	// deprecated cortexOrgID
 	{map[string]string{"serverAddress": "http://localhost:9090", "metricName": "http_requests_total", "threshold": "100", "query": "up", "cortexOrgID": "my-org"}, true},
+	// queryParameters
+	{map[string]string{"serverAddress": "http://localhost:9090", "metricName": "http_requests_total", "threshold": "100", "query": "up", "queryParameters": "key1=value1,key2=value2"}, false},
+	// queryParameters with wrong format
+	{map[string]string{"serverAddress": "http://localhost:9090", "metricName": "http_requests_total", "threshold": "100", "query": "up", "queryParameters": "key1=value1,key2"}, true},
 }
 
 var prometheusMetricIdentifiers = []prometheusMetricIdentifier{
@@ -372,6 +377,49 @@ func TestPrometheusScalerCustomHeaders(t *testing.T) {
 	assert.NoError(t, err)
 }
 
+func TestPrometheusScalerExecutePromQueryParameters(t *testing.T) {
+	testData := prometheusQromQueryResultTestData{
+		name:             "no values",
+		bodyStr:          `{"data":{"result":[]}}`,
+		responseStatus:   http.StatusOK,
+		expectedValue:    0,
+		isError:          false,
+		ignoreNullValues: true,
+	}
+	queryParametersValue := map[string]string{
+		"first":  "foo",
+		"second": "bar",
+	}
+	server := httptest.NewServer(http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
+		time := time.Now().UTC().Format(time.RFC3339)
+		expectedPath := fmt.Sprintf("/api/v1/query?query=&time=%s&first=foo&second=bar", time)
+		for queryParameterName, queryParameterValue := range queryParametersValue {
+			queryParameter := request.URL.Query()
+			queryParameter.Add(queryParameterName, queryParameterValue)
+		}
+
+		if request.RequestURI != expectedPath {
+			t.Error("Expect request path to =", expectedPath, "but it is", request.RequestURI)
+		}
+
+		writer.WriteHeader(testData.responseStatus)
+		if _, err := writer.Write([]byte(testData.bodyStr)); err != nil {
+			t.Fatal(err)
+		}
+	}))
+	scaler := prometheusScaler{
+		metadata: &prometheusMetadata{
+			serverAddress:    server.URL,
+			queryParameters:  queryParametersValue,
+			ignoreNullValues: testData.ignoreNullValues,
+		},
+		httpClient: http.DefaultClient,
+	}
+	_, err := scaler.ExecutePromQuery(context.TODO())
+
+	assert.NoError(t, err)
+}
+
 func TestPrometheusScaler_ExecutePromQuery_WithGCPNativeAuthentication(t *testing.T) {
 	fakeGoogleOAuthServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		fmt.Fprintln(w, `{"token_type": "Bearer", "access_token": "fake_access_token"}`)