Add resource to protocol

Signed-off-by: Fabian Reinartz <freinartz@google.com>

src/opencensus/proto/agent/common/v1/common.proto

@@ -44,6 +44,9 @@ message Node {
   // Additional attributes.
   map<string, string> attributes = 4;
 
+  // Default resource for all signals sent by the node.
+  Resource resource = 5;
+
   // TODO(songya): Add more identifiers in the future as needed, like cloud
   // identifiers.
 }
@@ -96,3 +99,13 @@ message ServiceInfo {
 
   // TODO(songya): add more fields as needed.
 }
+
+// Resource information.
+message Resource {
+
+  // Type identifier for the resource.
+  string type = 1;
+
+  // Set of labels that describe the resource.
+  map<string,string> = 2;
+}

src/opencensus/proto/agent/metrics/v1/metrics_service.proto

@@ -42,6 +42,10 @@ message ExportMetricsServiceRequest {
 
   // A list of metrics that belong to the last received Node.
   repeated opencensus.proto.metrics.v1.Metric metrics = 2;
+
+  // The resource for the metrics in this message. If unset, the resource of the
+  // most recent node applies.
+  opencensus.proto.agent.common.v1.Resource resource = 3;
 }
 
 message ExportMetricsServiceResponse {