Remove URL attribute, introduce path attribute

Also remove request and response size related attributes
to be compatible with the spec.

https://github.com/census-instrumentation/opencensus-specs/blob/master/trace/HTTPAttributes.md

exporter/stackdriver/trace_proto.go

@@ -36,14 +36,13 @@ const (
 	maxAttributeStringValue    = 256
 	agentLabel                 = "g.co/agent"
 
-	labelErrorMessage     = `trace.cloud.google.com/error/message`
-	labelHTTPHost         = `trace.cloud.google.com/http/host`
-	labelHTTPMethod       = `trace.cloud.google.com/http/method`
-	labelHTTPRequestSize  = `trace.cloud.google.com/http/request/size`
-	labelHTTPResponseSize = `trace.cloud.google.com/http/response/size`
-	labelHTTPStatusCode   = `trace.cloud.google.com/http/status_code`
-	labelHTTPURL          = `trace.cloud.google.com/http/url`
-	labelHTTPUserAgent    = `trace.cloud.google.com/http/user_agent`
+	labelHTTPHost         = `/http/host`
+	labelHTTPMethod       = `/http/method`
+	labelHTTPRequestSize  = `/http/request/size`
+	labelHTTPResponseSize = `/http/response/size`
+	labelHTTPStatusCode   = `/http/status_code`
+	labelHTTPPath         = `/http/path`
+	labelHTTPUserAgent    = `/http/user_agent`
 )
 
 // proto returns a protocol buffer representation of a SpanData.
@@ -178,8 +177,8 @@ func copyAttributes(out **tracepb.Span_Attributes, in map[string]interface{}) {
 			continue
 		}
 		switch key {
-		case ochttp.URLAttribute:
-			(*out).AttributeMap[labelHTTPURL] = av
+		case ochttp.PathAttribute:
+			(*out).AttributeMap[labelHTTPPath] = av
 		case ochttp.HostAttribute:
 			(*out).AttributeMap[labelHTTPHost] = av
 		case ochttp.MethodAttribute:

plugin/ochttp/trace.go

@@ -29,14 +29,11 @@ import (
 // Attributes recorded on the span for the requests.
 // Only trace exporters will need them.
 const (
-	URLAttribute          = "http.url"
-	HostAttribute         = "http.host"
-	MethodAttribute       = "http.method"
-	PathAttribute         = "http.path"
-	UserAgentAttribute    = "http.user_agent"
-	StatusCodeAttribute   = "http.status"
-	RequestSizeAttribute  = "http.request_size"
-	ResponseSizeAttribute = "http.response_size"
+	HostAttribute       = "http.host"
+	MethodAttribute     = "http.method"
+	PathAttribute       = "http.path"
+	UserAgentAttribute  = "http.user_agent"
+	StatusCodeAttribute = "http.status"
 )
 
 type traceTransport struct {
@@ -45,6 +42,8 @@ type traceTransport struct {
 	format  propagation.HTTPFormat
 }
 
+// TODO(jbd): Add message events for request and response size.
+
 // RoundTrip creates a trace.Span and inserts it into the outgoing request's headers.
 // The created span can follow a parent span, if a parent is presented in
 // the request's context.
@@ -68,7 +67,6 @@ func (t *traceTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 		return resp, err
 	}
 
-	// TODO(jbd): Set status based on the status code.
 	span.SetAttributes(responseAttrs(resp)...)
 
 	// span.End() will be invoked after
@@ -194,18 +192,16 @@ func spanNameFromURL(prefix string, u *url.URL) string {
 
 func requestAttrs(r *http.Request) []trace.Attribute {
 	return []trace.Attribute{
-		trace.StringAttribute{Key: URLAttribute, Value: r.URL.String()},
+		trace.StringAttribute{Key: PathAttribute, Value: r.URL.Path},
 		trace.StringAttribute{Key: HostAttribute, Value: r.URL.Host},
 		trace.StringAttribute{Key: MethodAttribute, Value: r.Method},
 		trace.StringAttribute{Key: PathAttribute, Value: r.URL.Path},
 		trace.StringAttribute{Key: UserAgentAttribute, Value: r.UserAgent()},
-		trace.Int64Attribute{Key: RequestSizeAttribute, Value: r.ContentLength},
 	}
 }
 
 func responseAttrs(resp *http.Response) []trace.Attribute {
 	return []trace.Attribute{
-		trace.Int64Attribute{Key: ResponseSizeAttribute, Value: resp.ContentLength},
 		trace.Int64Attribute{Key: StatusCodeAttribute, Value: int64(resp.StatusCode)},
 	}
 }