cloudfoundry/cf-k8s-controllers

package middleware

import (
    "net/http"

    "github.com/go-logr/logr"
    "github.com/google/uuid"
)

const CorrelationIDHeader = "X-Correlation-ID"

func Correlation(logger logr.Logger) func(http.Handler) http.Handler {
    return func(next http.Handler) http.Handler {
        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
            id := r.Header.Get(CorrelationIDHeader)
            if id == "" {
                id = uuid.NewString()
            }

            l := logger.WithValues("correlation-id", id)
            r = r.WithContext(logr.NewContext(r.Context(), l))

            w.Header().Add(CorrelationIDHeader, id)

            next.ServeHTTP(w, r)
        })
    }
}