| // Copyright 2018, OpenCensus Authors |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package ochttp |
| |
| import ( |
| "io" |
| "net/http" |
| "net/http/httptrace" |
| |
| "go.opencensus.io/plugin/ochttp/propagation/b3" |
| "go.opencensus.io/trace" |
| "go.opencensus.io/trace/propagation" |
| ) |
| |
| // TODO(jbd): Add godoc examples. |
| |
| var defaultFormat propagation.HTTPFormat = &b3.HTTPFormat{} |
| |
| // Attributes recorded on the span for the requests. |
| // Only trace exporters will need them. |
| const ( |
| HostAttribute = "http.host" |
| MethodAttribute = "http.method" |
| PathAttribute = "http.path" |
| URLAttribute = "http.url" |
| UserAgentAttribute = "http.user_agent" |
| StatusCodeAttribute = "http.status_code" |
| ) |
| |
| type traceTransport struct { |
| base http.RoundTripper |
| startOptions trace.StartOptions |
| format propagation.HTTPFormat |
| formatSpanName func(*http.Request) string |
| newClientTrace func(*http.Request, *trace.Span) *httptrace.ClientTrace |
| } |
| |
| // 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. |
| func (t *traceTransport) RoundTrip(req *http.Request) (*http.Response, error) { |
| name := t.formatSpanName(req) |
| // TODO(jbd): Discuss whether we want to prefix |
| // outgoing requests with Sent. |
| ctx, span := trace.StartSpan(req.Context(), name, |
| trace.WithSampler(t.startOptions.Sampler), |
| trace.WithSpanKind(trace.SpanKindClient)) |
| |
| if t.newClientTrace != nil { |
| req = req.WithContext(httptrace.WithClientTrace(ctx, t.newClientTrace(req, span))) |
| } else { |
| req = req.WithContext(ctx) |
| } |
| |
| if t.format != nil { |
| // SpanContextToRequest will modify its Request argument, which is |
| // contrary to the contract for http.RoundTripper, so we need to |
| // pass it a copy of the Request. |
| // However, the Request struct itself was already copied by |
| // the WithContext calls above and so we just need to copy the header. |
| header := make(http.Header) |
| for k, v := range req.Header { |
| header[k] = v |
| } |
| req.Header = header |
| t.format.SpanContextToRequest(span.SpanContext(), req) |
| } |
| |
| span.AddAttributes(requestAttrs(req)...) |
| resp, err := t.base.RoundTrip(req) |
| if err != nil { |
| span.SetStatus(trace.Status{Code: trace.StatusCodeUnknown, Message: err.Error()}) |
| span.End() |
| return resp, err |
| } |
| |
| span.AddAttributes(responseAttrs(resp)...) |
| span.SetStatus(TraceStatus(resp.StatusCode, resp.Status)) |
| |
| // span.End() will be invoked after |
| // a read from resp.Body returns io.EOF or when |
| // resp.Body.Close() is invoked. |
| bt := &bodyTracker{rc: resp.Body, span: span} |
| resp.Body = wrappedBody(bt, resp.Body) |
| return resp, err |
| } |
| |
| // bodyTracker wraps a response.Body and invokes |
| // trace.EndSpan on encountering io.EOF on reading |
| // the body of the original response. |
| type bodyTracker struct { |
| rc io.ReadCloser |
| span *trace.Span |
| } |
| |
| var _ io.ReadCloser = (*bodyTracker)(nil) |
| |
| func (bt *bodyTracker) Read(b []byte) (int, error) { |
| n, err := bt.rc.Read(b) |
| |
| switch err { |
| case nil: |
| return n, nil |
| case io.EOF: |
| bt.span.End() |
| default: |
| // For all other errors, set the span status |
| bt.span.SetStatus(trace.Status{ |
| // Code 2 is the error code for Internal server error. |
| Code: 2, |
| Message: err.Error(), |
| }) |
| } |
| return n, err |
| } |
| |
| func (bt *bodyTracker) Close() error { |
| // Invoking endSpan on Close will help catch the cases |
| // in which a read returned a non-nil error, we set the |
| // span status but didn't end the span. |
| bt.span.End() |
| return bt.rc.Close() |
| } |
| |
| // CancelRequest cancels an in-flight request by closing its connection. |
| func (t *traceTransport) CancelRequest(req *http.Request) { |
| type canceler interface { |
| CancelRequest(*http.Request) |
| } |
| if cr, ok := t.base.(canceler); ok { |
| cr.CancelRequest(req) |
| } |
| } |
| |
| func spanNameFromURL(req *http.Request) string { |
| return req.URL.Path |
| } |
| |
| func requestAttrs(r *http.Request) []trace.Attribute { |
| userAgent := r.UserAgent() |
| |
| attrs := make([]trace.Attribute, 0, 5) |
| attrs = append(attrs, |
| trace.StringAttribute(PathAttribute, r.URL.Path), |
| trace.StringAttribute(URLAttribute, r.URL.String()), |
| trace.StringAttribute(HostAttribute, r.Host), |
| trace.StringAttribute(MethodAttribute, r.Method), |
| ) |
| |
| if userAgent != "" { |
| attrs = append(attrs, trace.StringAttribute(UserAgentAttribute, userAgent)) |
| } |
| |
| return attrs |
| } |
| |
| func responseAttrs(resp *http.Response) []trace.Attribute { |
| return []trace.Attribute{ |
| trace.Int64Attribute(StatusCodeAttribute, int64(resp.StatusCode)), |
| } |
| } |
| |
| // TraceStatus is a utility to convert the HTTP status code to a trace.Status that |
| // represents the outcome as closely as possible. |
| func TraceStatus(httpStatusCode int, statusLine string) trace.Status { |
| var code int32 |
| if httpStatusCode < 200 || httpStatusCode >= 400 { |
| code = trace.StatusCodeUnknown |
| } |
| switch httpStatusCode { |
| case 499: |
| code = trace.StatusCodeCancelled |
| case http.StatusBadRequest: |
| code = trace.StatusCodeInvalidArgument |
| case http.StatusUnprocessableEntity: |
| code = trace.StatusCodeInvalidArgument |
| case http.StatusGatewayTimeout: |
| code = trace.StatusCodeDeadlineExceeded |
| case http.StatusNotFound: |
| code = trace.StatusCodeNotFound |
| case http.StatusForbidden: |
| code = trace.StatusCodePermissionDenied |
| case http.StatusUnauthorized: // 401 is actually unauthenticated. |
| code = trace.StatusCodeUnauthenticated |
| case http.StatusTooManyRequests: |
| code = trace.StatusCodeResourceExhausted |
| case http.StatusNotImplemented: |
| code = trace.StatusCodeUnimplemented |
| case http.StatusServiceUnavailable: |
| code = trace.StatusCodeUnavailable |
| case http.StatusOK: |
| code = trace.StatusCodeOK |
| } |
| return trace.Status{Code: code, Message: codeToStr[code]} |
| } |
| |
| var codeToStr = map[int32]string{ |
| trace.StatusCodeOK: `OK`, |
| trace.StatusCodeCancelled: `CANCELLED`, |
| trace.StatusCodeUnknown: `UNKNOWN`, |
| trace.StatusCodeInvalidArgument: `INVALID_ARGUMENT`, |
| trace.StatusCodeDeadlineExceeded: `DEADLINE_EXCEEDED`, |
| trace.StatusCodeNotFound: `NOT_FOUND`, |
| trace.StatusCodeAlreadyExists: `ALREADY_EXISTS`, |
| trace.StatusCodePermissionDenied: `PERMISSION_DENIED`, |
| trace.StatusCodeResourceExhausted: `RESOURCE_EXHAUSTED`, |
| trace.StatusCodeFailedPrecondition: `FAILED_PRECONDITION`, |
| trace.StatusCodeAborted: `ABORTED`, |
| trace.StatusCodeOutOfRange: `OUT_OF_RANGE`, |
| trace.StatusCodeUnimplemented: `UNIMPLEMENTED`, |
| trace.StatusCodeInternal: `INTERNAL`, |
| trace.StatusCodeUnavailable: `UNAVAILABLE`, |
| trace.StatusCodeDataLoss: `DATA_LOSS`, |
| trace.StatusCodeUnauthenticated: `UNAUTHENTICATED`, |
| } |
| |
| func isHealthEndpoint(path string) bool { |
| // Health checking is pretty frequent and |
| // traces collected for health endpoints |
| // can be extremely noisy and expensive. |
| // Disable canonical health checking endpoints |
| // like /healthz and /_ah/health for now. |
| if path == "/healthz" || path == "/_ah/health" { |
| return true |
| } |
| return false |
| } |