tailscale/tsweb/request_id.go
Joe Tsai c25968e1c5
all: make use of ctxkey everywhere (#10846)
Also perform minor cleanups on the ctxkey package itself.
Provide guidance on when to use ctxkey.Key[T] over ctxkey.New.
Also, allow for interface kinds because the value wrapping trick
also happens to fix edge cases with interfaces in Go.

Updates #cleanup

Signed-off-by: Joe Tsai <joetsai@digital-static.net>
2024-01-16 13:56:23 -08:00

62 lines
2.2 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package tsweb
import (
"context"
"net/http"
"github.com/google/uuid"
"tailscale.com/util/ctxkey"
)
// RequestID is an opaque identifier for a HTTP request, used to correlate
// user-visible errors with backend server logs. The RequestID is typically
// threaded through an HTTP Middleware (WithRequestID) and then can be extracted
// by HTTP Handlers to include in their logs.
//
// RequestID is an opaque identifier for a HTTP request, used to correlate
// user-visible errors with backend server logs. If present in the context, the
// RequestID will be printed alongside the message text and logged in the
// AccessLogRecord.
//
// A RequestID has the format "REQ-1{ID}", and the ID should be treated as an
// opaque string. The current implementation uses a UUID.
type RequestID string
// RequestIDKey stores and loads [RequestID] values within a [context.Context].
var RequestIDKey ctxkey.Key[RequestID]
// RequestIDHeader is a custom HTTP header that the WithRequestID middleware
// uses to determine whether to re-use a given request ID from the client
// or generate a new one.
const RequestIDHeader = "X-Tailscale-Request-Id"
// SetRequestID is an HTTP middleware that injects a RequestID in the
// *http.Request Context. The value of that request id is either retrieved from
// the RequestIDHeader or a randomly generated one if not exists. Inner
// handlers can retrieve this ID from the RequestIDFromContext function.
func SetRequestID(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
id := r.Header.Get(RequestIDHeader)
if id == "" {
// REQ-1 indicates the version of the RequestID pattern. It is
// currently arbitrary but allows for forward compatible
// transitions if needed.
id = "REQ-1" + uuid.NewString()
}
ctx := RequestIDKey.WithValue(r.Context(), RequestID(id))
r = r.WithContext(ctx)
h.ServeHTTP(w, r)
})
}
// RequestIDFromContext retrieves the RequestID from context that can be set by
// the SetRequestID function.
//
// Deprecated: Use [RequestIDKey.Value] instead.
func RequestIDFromContext(ctx context.Context) RequestID {
return RequestIDKey.Value(ctx)
}