telegraf/plugins/inputs/zipkin/handler.go

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2017-08-03 00:58:26 +00:00
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
}