forked from zenazn/goji
/
request_id.go
69 lines (59 loc) · 1.63 KB
/
request_id.go
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package middleware
import (
"crypto/rand"
"encoding/base64"
"fmt"
"net/http"
"os"
"strings"
"sync/atomic"
"github.com/zenazn/goji/web"
)
// Key to use when setting the request ID.
const RequestIDKey = "reqID"
var prefix string
var reqid uint64
func init() {
hostname, err := os.Hostname()
if hostname == "" || err != nil {
hostname = "localhost"
}
var buf [12]byte
rand.Read(buf[:])
b64 := base64.StdEncoding.EncodeToString(buf[:])
// Strip out annoying characters. We have something like a billion to
// one chance of having enough from 12 bytes of entropy
b64 = strings.NewReplacer("+", "", "/", "").Replace(b64)
prefix = fmt.Sprintf("%s/%s", hostname, b64[0:8])
}
// RequestID is a middleware that injects a request ID into the context of each
// request. A request ID is a string of the form "host.example.com/random-0001",
// where "random" is a base62 random string that uniquely identifies this go
// process, and where the last number is an atomically incremented request
// counter.
func RequestID(c *web.C, h http.Handler) http.Handler {
fn := func(w http.ResponseWriter, r *http.Request) {
if c.Env == nil {
c.Env = make(map[string]interface{})
}
myid := atomic.AddUint64(&reqid, 1)
c.Env[RequestIDKey] = fmt.Sprintf("%s-%06d", prefix, myid)
h.ServeHTTP(w, r)
}
return http.HandlerFunc(fn)
}
// GetReqID returns a request ID from the given context if one is present.
// Returns the empty string if a request ID cannot be found.
func GetReqID(c web.C) string {
if c.Env == nil {
return ""
}
v, ok := c.Env[RequestIDKey]
if !ok {
return ""
}
if reqID, ok := v.(string); ok {
return reqID
}
return ""
}