I have two ways (middleware) of setting a specific header (if not set) to request but want to know if one is better/beneficial than the other and the reasons why.

Note: At some point I will need to log X-Request-Id value in every single application log I have. If this plan affects your answer, I don't know. Just saying!

Context version

package middleware

import (
    "context"
    "github.com/google/uuid"
    "net/http"
)

type ReqIdKey int
const ReqId ReqIdKey = 0

func RequestId(handler http.Handler) http.Handler {
    return http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
        XReqID := req.Header.Get("X-Request-Id")
        if XReqID == "" {
            XReqID = uuid.New().String()
        }

        ctx1 := context.WithValue(req.Context(), ReqId, XReqID)
        ctx2 := req.WithContext(ctx1)

        handler.ServeHTTP(res, ctx2)
    })
}

Without context version

package middleware

import (
    "github.com/google/uuid"
    "net/http"
)

func RequestId(handler http.Handler) http.Handler {
    return http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
        if req.Header.Get("X-Request-Id") == "" {
            req.Header.Set("X-Request-Id", uuid.New().String())
        }

        handler.ServeHTTP(res, req)
    })
}

Usage

err := http.ListenAndServe(":8080", middleware.RequestId(Router))

I have two ways (middleware) of setting a specific header (if not set) to request but want to know if one is better/beneficial than the other and the reasons why.

Note: At some point I will need to log X-Request-Id value in every single application log I have. If this plan affects your answer, I don't know. Just saying!

Context version

package middleware

import (
    "context"
    "github.com/google/uuid"
    "net/http"
)

type CtxKey string
const CtxReqIdKey CtxKey = "X-Request-Id"

func RequestId(handler http.Handler) http.Handler {
    return http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
        CtxKey := req.Header.Get("X-Request-Id")
        if CtxKey == "" {
            CtxKey = uuid.New().String()
        }

        ctx1 := context.WithValue(req.Context(), CtxReqIdKey, CtxKey)
        ctx2 := req.WithContext(ctx1)

        handler.ServeHTTP(res, ctx2)
    })
}

# Elsewhere: request.Context().Value(middleware.CtxReqIdKey)

Without context version

package middleware

import (
    "github.com/google/uuid"
    "net/http"
)

func RequestId(handler http.Handler) http.Handler {
    return http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
        if req.Header.Get("X-Request-Id") == "" {
            req.Header.Set("X-Request-Id", uuid.New().String())
        }

        handler.ServeHTTP(res, req)
    })
}

Usage

err := http.ListenAndServe(":8080", middleware.RequestId(Router))