Add Resource to Span (#174)

* Add Resource to Span

* Add missing import

* Update to correct id and increment next id

* PR comments

* Add resource to bazel build dep

* Add another dependency

* PR comments

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

@@ -27,8 +27,8 @@ option java_outer_classname = "CommonProto";
 
 option go_package = "github.com/census-instrumentation/opencensus-proto/gen-go/agent/common/v1";
 
-// Identifier metadata of the Node (Application instrumented with OpenCensus)
-// that connects to OpenCensus Agent.
+// Identifier metadata of the Node that produces the span or tracing data.
+// Note, this is not the metadata about the Node or service that is described by associated spans.
 // In the future we plan to extend the identifier proto definition to support
 // additional information (e.g cloud id, etc.)
 message Node {

src/opencensus/proto/trace/v1/BUILD.bazel

@@ -23,6 +23,7 @@ proto_library(
     deps = [
         "@com_google_protobuf//:timestamp_proto",
         "@com_google_protobuf//:wrappers_proto",
+        "//opencensus/proto/resource/v1:resource_proto",
     ],
 )
 
@@ -58,6 +59,7 @@ go_proto_library(
     deps = [
         "@com_github_golang_protobuf//ptypes/timestamp:go_default_library",
         "@com_github_golang_protobuf//ptypes/wrappers:go_default_library",
+        "//opencensus/proto/resource/v1:resource_proto_go",
     ],
 )
 

src/opencensus/proto/trace/v1/trace.proto

@@ -16,6 +16,7 @@ syntax = "proto3";
 
 package opencensus.proto.trace.v1;
 
+import "opencensus/proto/resource/v1/resource.proto";
 import "google/protobuf/timestamp.proto";
 import "google/protobuf/wrappers.proto";
 
@@ -33,7 +34,7 @@ option go_package = "github.com/census-instrumentation/opencensus-proto/gen-go/t
 // multiple root spans, or none at all. Spans do not need to be
 // contiguous - there may be gaps or overlaps between spans in a trace.
 //
-// The next id is 16.
+// The next id is 17.
 // TODO(bdrutu): Add an example.
 message Span {
   // A unique identifier for a trace. All spans from the same trace share
@@ -290,6 +291,11 @@ message Span {
   // Status.Ok (code = 0).
   Status status = 11;
 
+  // An optional resource that is associated with this span. If not set, this span 
+  // should be part of a batch that does include the resource information, unless resource 
+  // information is unknown.
+  opencensus.proto.resource.v1.Resource resource = 16;
+
   // A highly recommended but not required flag that identifies when a
   // trace crosses a process boundary. True when the parent_span belongs
   // to the same process as the current span. This flag is most commonly