Fix: Preserve Jaeger base path when constructing search request (#109045)

* fix url construction

* consistency

* update error response

* error source

* add test case

pkg/tsdb/jaeger/client.go

@@ -115,11 +115,15 @@ func (j *JaegerClient) Operations(s string) ([]string, error) {
 }
 
 func (j *JaegerClient) Search(query *JaegerQuery, start, end int64) ([]TraceResponse, error) {
-	jaegerURL, err := url.Parse(j.url)
+	u, err := url.JoinPath(j.url, "/api/traces")
 	if err != nil {
-		return []TraceResponse{}, fmt.Errorf("failed to parse Jaeger URL: %w", err)
+		return []TraceResponse{}, backend.DownstreamError(fmt.Errorf("failed to join url path: %w", err))
+	}
+
+	jaegerURL, err := url.Parse(u)
+	if err != nil {
+		return []TraceResponse{}, backend.DownstreamError(fmt.Errorf("failed to parse Jaeger URL: %w", err))
 	}
-	jaegerURL.Path = "/api/traces"
 
 	var queryTags string
 	if query.Tags != "" {
@@ -135,7 +139,7 @@ func (j *JaegerClient) Search(query *JaegerQuery, start, end int64) ([]TraceResp
 
 		marshaledTags, err := json.Marshal(tagMap)
 		if err != nil {
-			return []TraceResponse{}, fmt.Errorf("failed to convert tags to JSON: %w", err)
+			return []TraceResponse{}, backend.DownstreamError(fmt.Errorf("failed to convert tags to JSON: %w", err))
 		}
 
 		queryTags = string(marshaledTags)

pkg/tsdb/jaeger/client_test.go

@@ -186,6 +186,19 @@ func TestJaegerClient_Search(t *testing.T) {
 		expectError    bool
 		expectedError  error
 	}{
+		{
+			name: "Preserves base path in Jaeger URL",
+			query: &JaegerQuery{
+				Service: "test-service",
+			},
+			start:          1735689600000000,
+			end:            1738368000000000,
+			mockResponse:   `{"data":[{"traceID":"test-trace-id"}]}`,
+			mockStatusCode: http.StatusOK,
+			expectedURL:    "/abc/api/traces?end=1738368000000000&service=test-service&start=1735689600000000",
+			expectError:    false,
+			expectedError:  nil,
+		},
 		{
 			name: "Successful search with all parameters",
 			query: &JaegerQuery{
@@ -245,6 +258,11 @@ func TestJaegerClient_Search(t *testing.T) {
 			settings := backend.DataSourceInstanceSettings{
 				URL: server.URL,
 			}
+
+			if tt.name == "Preserves base path in Jaeger URL" {
+				settings.URL = server.URL + "/abc"
+			}
+
 			client, err := New(server.Client(), log.NewNullLogger(), settings)
 			assert.NoError(t, err)
 			traces, err := client.Search(tt.query, tt.start, tt.end)