PR #292: Add unique request id

This patch add proxy.header.requestid configuration option
for specifying header name for adding unique ID to each http
request proxied by fabio.

This header value can be logged in fabio access log and used
for request processing tracking across different request
handling applications.

config/config.go

@@ -57,6 +57,7 @@ type Proxy struct {
 	TLSHeader             string
 	TLSHeaderValue        string
 	GZIPContentTypes      *regexp.Regexp
+	RequestID             string
 }
 
 type Runtime struct {

config/load.go

@@ -126,6 +126,7 @@ func load(cmdline, environ, envprefix []string, props *properties.Properties) (c
 	f.StringVar(&cfg.Proxy.ClientIPHeader, "proxy.header.clientip", defaultConfig.Proxy.ClientIPHeader, "header for the request ip")
 	f.StringVar(&cfg.Proxy.TLSHeader, "proxy.header.tls", defaultConfig.Proxy.TLSHeader, "header for TLS connections")
 	f.StringVar(&cfg.Proxy.TLSHeaderValue, "proxy.header.tls.value", defaultConfig.Proxy.TLSHeaderValue, "value for TLS connection header")
+	f.StringVar(&cfg.Proxy.RequestID, "proxy.header.requestid", defaultConfig.Proxy.RequestID, "header for reqest id")
 	f.StringVar(&gzipContentTypesValue, "proxy.gzip.contenttype", defaultValues.GZIPContentTypesValue, "regexp of content types to compress")
 	f.StringSliceVar(&listenerValue, "proxy.addr", defaultValues.ListenerValue, "listener config")
 	f.KVSliceVar(&certSourcesValue, "proxy.cs", defaultValues.CertSourcesValue, "certificate sources")

config/load_test.go

@@ -302,6 +302,13 @@ func TestLoad(t *testing.T) {
 				return cfg
 			},
 		},
+		{
+			args: []string{"-proxy.header.requestid", "value"},
+			cfg: func(cfg *Config) *Config {
+				cfg.Proxy.RequestID = "value"
+				return cfg
+			},
+		},
 		{
 			args: []string{"-proxy.gzip.contenttype", `^text/.*$`},
 			cfg: func(cfg *Config) *Config {

fabio.properties

@@ -353,6 +353,15 @@
 # proxy.header.tls.value =
 
 
+# proxy.header.requestid configures the header for the adding a unique request id.
+# When set non-empty value the proxy will set this header on every request to the
+# unique UUID value.
+#
+# The default is
+#
+# proxy.header.requestid =
+
+
 # proxy.gzip.contenttype configures which responses should be compressed.
 #
 # By default, responses sent to the client are not compressed even if the

proxy/http_integration_test.go

@@ -50,6 +50,31 @@ func TestProxyProducesCorrectXffHeader(t *testing.T) {
 	}
 }
 
+func TestProxyRequestIDHeader(t *testing.T) {
+	got := "not called"
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		got = r.Header.Get("X-Request-ID")
+	}))
+	defer server.Close()
+
+	proxy := httptest.NewServer(&HTTPProxy{
+		Config:    config.Proxy{RequestID: "X-Request-Id"},
+		Transport: http.DefaultTransport,
+		UUID:      func() string { return "f47ac10b-58cc-0372-8567-0e02b2c3d479" },
+		Lookup: func(r *http.Request) *route.Target {
+			return &route.Target{URL: mustParse(server.URL)}
+		},
+	})
+	defer proxy.Close()
+
+	req, _ := http.NewRequest("GET", proxy.URL, nil)
+	mustDo(req)
+
+	if want := "f47ac10b-58cc-0372-8567-0e02b2c3d479"; got != want {
+		t.Errorf("got %v, but want %v", got, want)
+	}
+}
+
 func TestProxyNoRouteStaus(t *testing.T) {
 	proxy := httptest.NewServer(&HTTPProxy{
 		Config:    config.Proxy{NoRouteStatus: 999},

proxy/http_proxy.go

@@ -15,6 +15,7 @@ import (
 	"github.com/fabiolb/fabio/metrics"
 	"github.com/fabiolb/fabio/proxy/gzip"
 	"github.com/fabiolb/fabio/route"
+	"github.com/fabiolb/fabio/uuid"
 )
 
 // HTTPProxy is a dynamic reverse proxy for HTTP and HTTPS protocols.
@@ -48,6 +49,10 @@ type HTTPProxy struct {
 
 	// Logger is the access logger for the requests.
 	Logger logger.Logger
+
+	// UUID returns a unique id in uuid format.
+	// If UUID is nil, uuid.NewUUID() is used.
+	UUID func() string
 }
 
 func (p *HTTPProxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -66,6 +71,14 @@ func (p *HTTPProxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if p.Config.RequestID != "" {
+		id := p.UUID
+		if id == nil {
+			id = uuid.NewUUID
+		}
+		r.Header.Set(p.Config.RequestID, id())
+	}
+
 	// build the request url since r.URL will get modified
 	// by the reverse proxy and contains only the RequestURI anyway
 	requestURL := &url.URL{

uuid/format.go

@@ -0,0 +1,62 @@
+package uuid
+
+// Fast UUID formatting adapted from
+// https://github.com/m4rw3r/uuid/blob/master/uuid.go
+
+// hexchar2byte contains the integer byte-value represented by a hexadecimal character,
+// 255 if it is an invalid character.
+var hexchar2byte = []byte{
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 255, 255, 255, 255, 255, 255,
+	255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+}
+
+// halfbyte2hexchar contains an array of character values corresponding to
+// hexadecimal values for the position in the array, 0 to 15 (0x0-0xf, half-byte).
+var halfbyte2hexchar = []byte{
+	48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 97, 98, 99, 100, 101, 102,
+}
+
+// ToString formats raw UUID bytes as a standard UUID string
+func ToString(u [24]byte) string {
+	/* It is a lot (~10x) faster to allocate a byte slice of specific size and
+	   then use a lookup table to write the characters to the byte-array and
+	   finally cast to string instead of using fmt.Sprintf() */
+	/* Slightly faster to not use make([]byte, 36), guessing either call
+	   overhead or slice-header overhead is the cause */
+	b := [36]byte{}
+
+	for i, n := range []int{
+		0, 2, 4, 6,
+		9, 11,
+		14, 16,
+		19, 21,
+		24, 26, 28, 30, 32, 34,
+	} {
+		b[n] = halfbyte2hexchar[(u[i]>>4)&0x0f]
+		b[n+1] = halfbyte2hexchar[u[i]&0x0f]
+	}
+
+	b[8] = '-'
+	b[13] = '-'
+	b[18] = '-'
+	b[23] = '-'
+
+	/* Oddly does not seem to cause a memory allocation,
+	   internal data-array is most likely just moved over
+	   to the string-header: */
+	return string(b[:])
+}

uuid/uuid.go

@@ -0,0 +1,12 @@
+package uuid
+
+import (
+	"github.com/rogpeppe/fastuuid"
+)
+
+var generator = fastuuid.MustNewGenerator()
+
+// NewUUID return UUID in string fromat
+func NewUUID() string {
+	return ToString(generator.Next())
+}