Add Zipkin input plugin (#3080)

plugins/inputs/zipkin/handler.go

@@ -0,0 +1,135 @@
+package zipkin
+
+import (
+	"compress/gzip"
+	"io/ioutil"
+	"net/http"
+	"strings"
+	"sync"
+
+	"github.com/apache/thrift/lib/go/thrift"
+	"github.com/gorilla/mux"
+	"github.com/openzipkin/zipkin-go-opentracing/_thrift/gen-go/zipkincore"
+)
+
+// SpanHandler is an implementation of a Handler which accepts zipkin thrift
+// span data and sends it to the recorder
+type SpanHandler struct {
+	Path      string
+	recorder  Recorder
+	waitGroup *sync.WaitGroup
+}
+
+// NewSpanHandler returns a new server instance given path to handle
+func NewSpanHandler(path string) *SpanHandler {
+	return &SpanHandler{
+		Path: path,
+	}
+}
+
+func cors(next http.HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if origin := r.Header.Get("Origin"); origin != "" {
+			w.Header().Set(`Access-Control-Allow-Origin`, origin)
+			w.Header().Set(`Access-Control-Allow-Methods`, strings.Join([]string{
+				`OPTIONS`,
+				`POST`,
+			}, ", "))
+
+			w.Header().Set(`Access-Control-Allow-Headers`, strings.Join([]string{
+				`Accept`,
+				`Accept-Encoding`,
+				`Content-Length`,
+				`Content-Type`,
+			}, ", "))
+
+			w.Header().Set(`Access-Control-Expose-Headers`, strings.Join([]string{
+				`Date`,
+			}, ", "))
+		}
+
+		if r.Method == "OPTIONS" {
+			return
+		}
+
+		next.ServeHTTP(w, r)
+	}
+}
+
+// Register implements the Service interface. Register accepts zipkin thrift data
+// POSTed to the path of the mux router
+func (s *SpanHandler) Register(router *mux.Router, recorder Recorder) error {
+	handler := cors(http.HandlerFunc(s.Spans))
+	router.Handle(s.Path, handler).Methods("POST", "OPTIONS")
+	s.recorder = recorder
+	return nil
+}
+
+// Spans handles zipkin thrift spans
+func (s *SpanHandler) Spans(w http.ResponseWriter, r *http.Request) {
+	defer r.Body.Close()
+	body := r.Body
+	var err error
+	// Handle gzip decoding of the body
+	if r.Header.Get("Content-Encoding") == "gzip" {
+		body, err = gzip.NewReader(r.Body)
+		if err != nil {
+			s.recorder.Error(err)
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		defer body.Close()
+	}
+
+	octets, err := ioutil.ReadAll(body)
+	if err != nil {
+		s.recorder.Error(err)
+		w.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+
+	spans, err := unmarshalThrift(octets)
+	if err != nil {
+		s.recorder.Error(err)
+		w.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+
+	trace := NewTrace(spans)
+
+	if err = s.recorder.Record(trace); err != nil {
+		s.recorder.Error(err)
+		w.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+
+	w.WriteHeader(http.StatusNoContent)
+}
+
+func unmarshalThrift(body []byte) ([]*zipkincore.Span, error) {
+	buffer := thrift.NewTMemoryBuffer()
+	if _, err := buffer.Write(body); err != nil {
+		return nil, err
+	}
+
+	transport := thrift.NewTBinaryProtocolTransport(buffer)
+	_, size, err := transport.ReadListBegin()
+	if err != nil {
+		return nil, err
+	}
+
+	spans := make([]*zipkincore.Span, size)
+	for i := 0; i < size; i++ {
+		zs := &zipkincore.Span{}
+		if err = zs.Read(transport); err != nil {
+			return nil, err
+		}
+		spans[i] = zs
+	}
+
+	if err = transport.ReadListEnd(); err != nil {
+		return nil, err
+	}
+
+	return spans, nil
+}