Merge pull request #373 from zalando-incubator/json-path-array

Handle more complex array in json path

pkg/collector/httpmetrics/json_path.go

@@ -72,10 +72,25 @@ func (g *JSONPathMetricsGetter) GetMetric(metricsURL url.URL) (float64, error) {
 		return 0, err
 	}
 
-	if len(nodes) != 1 {
+	if len(nodes) == 0 {
 		return 0, fmt.Errorf("unexpected json: expected single numeric or array value")
 	}
 
+	if len(nodes) > 1 {
+		if g.aggregator == nil {
+			return 0, fmt.Errorf("no aggregator function has been specified")
+		}
+		values := make([]float64, 0, len(nodes))
+		for _, node := range nodes {
+			v, err := node.GetNumeric()
+			if err != nil {
+				return 0, fmt.Errorf("unexpected json: did not find numeric or array value '%s': %w", nodes, err)
+			}
+			values = append(values, v)
+		}
+		return g.aggregator(values...), nil
+	}
+
 	node := nodes[0]
 	if node.IsArray() {
 		if g.aggregator == nil {

pkg/collector/httpmetrics/json_path_test.go

@@ -51,6 +51,13 @@ func TestJSONPathMetricsGetter(t *testing.T) {
 			result:       5,
 			aggregator:   Average,
 		},
+		{
+			name:         "glob array query",
+			jsonResponse: []byte(`{"worker_status":[{"last_status":{"backlog":3}},{"last_status":{"backlog":7}}]}`),
+			jsonPath:     "$.worker_status.[*].last_status.backlog",
+			result:       5,
+			aggregator:   Average,
+		},
 		{
 			name:         "json path not resulting in array or number should lead to error",
 			jsonResponse: []byte(`{"metric.value":5}`),