64 lines
2 KiB
Go
64 lines
2 KiB
Go
package tracing
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import (
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"fmt"
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"net/http"
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"github.com/containous/traefik/log"
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"github.com/opentracing/opentracing-go/ext"
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"github.com/urfave/negroni"
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)
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type forwarderMiddleware struct {
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frontend string
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backend string
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opName string
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*Tracing
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}
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// NewForwarderMiddleware creates a new forwarder middleware that traces the outgoing request
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func (t *Tracing) NewForwarderMiddleware(frontend, backend string) negroni.Handler {
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log.Debugf("Added outgoing tracing middleware %s", frontend)
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return &forwarderMiddleware{
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Tracing: t,
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frontend: frontend,
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backend: backend,
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opName: generateForwardSpanName(frontend, backend, t.SpanNameLimit),
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}
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}
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func (f *forwarderMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
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span, r, finish := StartSpan(r, f.opName, true)
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defer finish()
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span.SetTag("frontend.name", f.frontend)
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span.SetTag("backend.name", f.backend)
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ext.HTTPMethod.Set(span, r.Method)
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ext.HTTPUrl.Set(span, fmt.Sprintf("%s%s", r.URL.String(), r.RequestURI))
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span.SetTag("http.host", r.Host)
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InjectRequestHeaders(r)
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recorder := newStatusCodeRecoder(w, 200)
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next(recorder, r)
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LogResponseCode(span, recorder.Status())
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}
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// generateForwardSpanName will return a Span name of an appropriate lenth based on the 'spanLimit' argument. If needed, it will be truncated, but will not be less than 21 characters
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func generateForwardSpanName(frontend, backend string, spanLimit int) string {
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name := fmt.Sprintf("forward %s/%s", frontend, backend)
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if spanLimit > 0 && len(name) > spanLimit {
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if spanLimit < ForwardMaxLengthNumber {
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log.Warnf("SpanNameLimit is set to be less than required static number of characters, defaulting to %d + 3", ForwardMaxLengthNumber)
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spanLimit = ForwardMaxLengthNumber + 3
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}
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hash := computeHash(name)
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limit := (spanLimit - ForwardMaxLengthNumber) / 2
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name = fmt.Sprintf("forward %s/%s/%s", truncateString(frontend, limit), truncateString(backend, limit), hash)
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}
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return name
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}
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