69 lines
1.6 KiB
Go
69 lines
1.6 KiB
Go
package tracing
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import (
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"context"
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"net/http"
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"github.com/containous/alice"
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"github.com/opentracing/opentracing-go/ext"
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"github.com/traefik/traefik/v2/pkg/log"
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"github.com/traefik/traefik/v2/pkg/tracing"
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)
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// Traceable embeds tracing information.
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type Traceable interface {
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GetTracingInformation() (name string, spanKind ext.SpanKindEnum)
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}
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// Wrap adds traceability to an alice.Constructor.
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func Wrap(ctx context.Context, constructor alice.Constructor) alice.Constructor {
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return func(next http.Handler) (http.Handler, error) {
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if constructor == nil {
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return nil, nil
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}
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handler, err := constructor(next)
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if err != nil {
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return nil, err
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}
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if traceableHandler, ok := handler.(Traceable); ok {
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name, spanKind := traceableHandler.GetTracingInformation()
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log.FromContext(ctx).WithField(log.MiddlewareName, name).Debug("Adding tracing to middleware")
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return NewWrapper(handler, name, spanKind), nil
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}
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return handler, nil
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}
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}
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// NewWrapper returns a http.Handler struct.
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func NewWrapper(next http.Handler, name string, spanKind ext.SpanKindEnum) http.Handler {
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return &Wrapper{
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next: next,
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name: name,
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spanKind: spanKind,
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}
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}
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// Wrapper is used to wrap http handler middleware.
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type Wrapper struct {
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next http.Handler
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name string
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spanKind ext.SpanKindEnum
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}
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func (w *Wrapper) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
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_, err := tracing.FromContext(req.Context())
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if err != nil {
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w.next.ServeHTTP(rw, req)
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return
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}
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var finish func()
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_, req, finish = tracing.StartSpan(req, w.name, w.spanKind)
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defer finish()
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if w.next != nil {
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w.next.ServeHTTP(rw, req)
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}
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}
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