metrics: Proto Resource to monitoredresource.Resource

A converter for:
    OpenCensus Proto Resource
to
    monitoredresource.Resource

Updates #64.

Author: odeke-em

metrics.go

@@ -29,9 +29,11 @@ import (
 	distributionpb "google.golang.org/genproto/googleapis/api/distribution"
 	labelpb "google.golang.org/genproto/googleapis/api/label"
 	googlemetricpb "google.golang.org/genproto/googleapis/api/metric"
+	monitoredrespb "google.golang.org/genproto/googleapis/api/monitoredres"
 	monitoringpb "google.golang.org/genproto/googleapis/monitoring/v3"
 
 	metricspb "github.com/census-instrumentation/opencensus-proto/gen-go/metrics/v1"
+	resourcepb "github.com/census-instrumentation/opencensus-proto/gen-go/resource/v1"
 )
 
 var errNilMetric = errors.New("expecting a non-nil metric")
@@ -238,3 +240,19 @@ func protoMetricDescriptorTypeToMetricKind(m *metricspb.Metric) (googlemetricpb.
 		return googlemetricpb.MetricDescriptor_METRIC_KIND_UNSPECIFIED, googlemetricpb.MetricDescriptor_VALUE_TYPE_UNSPECIFIED
 	}
 }
+
+func protoResourceToMonitoredResource(rsp *resourcepb.Resource) *monitoredrespb.MonitoredResource {
+	if rsp == nil {
+		return nil
+	}
+	mrsp := &monitoredrespb.MonitoredResource{
+		Type: rsp.Type,
+	}
+	if rsp.Labels != nil {
+		mrsp.Labels = make(map[string]string, len(rsp.Labels))
+		for k, v := range rsp.Labels {
+			mrsp.Labels[k] = v
+		}
+	}
+	return mrsp
+}

metrics_test.go

@@ -23,11 +23,61 @@ import (
 	"github.com/golang/protobuf/ptypes/timestamp"
 	distributionpb "google.golang.org/genproto/googleapis/api/distribution"
 	googlemetricpb "google.golang.org/genproto/googleapis/api/metric"
+	monitoredrespb "google.golang.org/genproto/googleapis/api/monitoredres"
 	monitoringpb "google.golang.org/genproto/googleapis/monitoring/v3"
 
 	metricspb "github.com/census-instrumentation/opencensus-proto/gen-go/metrics/v1"
+	resourcepb "github.com/census-instrumentation/opencensus-proto/gen-go/resource/v1"
 )
 
+func TestProtoResourceToMonitoringResource(t *testing.T) {
+	tests := []struct {
+		in   *resourcepb.Resource
+		want *monitoredrespb.MonitoredResource
+	}{
+		{in: nil, want: nil},
+		{in: &resourcepb.Resource{}, want: &monitoredrespb.MonitoredResource{}},
+		{
+			in: &resourcepb.Resource{
+				Type: "foo",
+			},
+			want: &monitoredrespb.MonitoredResource{
+				Type: "foo",
+			},
+		},
+		{
+			in: &resourcepb.Resource{
+				Type:   "foo",
+				Labels: map[string]string{},
+			},
+			want: &monitoredrespb.MonitoredResource{
+				Type:   "foo",
+				Labels: map[string]string{},
+			},
+		},
+		{
+			in: &resourcepb.Resource{
+				Type:   "foo",
+				Labels: map[string]string{"a": "A"},
+			},
+			want: &monitoredrespb.MonitoredResource{
+				Type:   "foo",
+				Labels: map[string]string{"a": "A"},
+			},
+		},
+	}
+
+	for i, tt := range tests {
+		got := protoResourceToMonitoredResource(tt.in)
+		if !reflect.DeepEqual(got, tt.want) {
+			gj, wj := serializeAsJSON(got), serializeAsJSON(tt.want)
+			if gj != wj {
+				t.Errorf("#%d: Unmatched JSON\nGot:\n\t%s\nWant:\n\t%s", i, gj, wj)
+			}
+		}
+	}
+}
+
 func TestProtoToMonitoringMetricDescriptor(t *testing.T) {
 	tests := []struct {
 		in      *metricspb.Metric