Serve expvar information from HTTP package

etc/config.sample.toml

@@ -97,7 +97,6 @@ reporting-disabled = false
   store-database = "_internal" # The destination database for recorded statistics
   store-interval = "1m" # The interval at which to record statistics
   store-address = "http://127.0.0.1" # The protocol and host for the recorded data
-  # expvar-address = "127.0.0.1:9950" # Unset to expose expvar data over HTTP.
 
 ###
 ### [admin]

monitor/config.go

@@ -27,7 +27,6 @@ type Config struct {
 	StoreDatabase string        `toml:"store-database"`
 	StoreInterval toml.Duration `toml:"store-interval"`
 	StoreAddress  string        `toml:"store-address"`
-	ExpvarAddress string        `toml:"expvar-address"`
 }
 
 // NewConfig returns an instance of Config with defaults.

monitor/config_test.go

@@ -16,21 +16,18 @@ store-enabled=true
 store-database="the_db"
 store-interval="10m"
 store-address="server1"
-expvar-address="127.0.0.1:9950"
 `, &c); err != nil {
 		t.Fatal(err)
 	}
 
 	// Validate configuration.
 	if !c.StoreEnabled {
-		t.Fatalf("unexpected store-enabled: %s", c.StoreEnabled)
+		t.Fatalf("unexpected store-enabled: %v", c.StoreEnabled)
 	} else if c.StoreDatabase != "the_db" {
 		t.Fatalf("unexpected store-database: %s", c.StoreDatabase)
 	} else if time.Duration(c.StoreInterval) != 10*time.Minute {
 		t.Fatalf("unexpected store-interval:  %s", c.StoreInterval)
 	} else if c.StoreAddress != "server1" {
 		t.Fatalf("unexpected store-address: %s", c.StoreAddress)
-	} else if c.ExpvarAddress != "127.0.0.1:9950" {
-		t.Fatalf("unexpected expvar-address: %s", c.ExpvarAddress)
 	}
 }

monitor/service.go

@@ -4,7 +4,6 @@ import (
 	"expvar"
 	"fmt"
 	"log"
-	"net"
 	"net/http"
 	"net/url"
 	"os"
@@ -38,8 +37,6 @@ type Service struct {
 	storeAddress  string
 	storeInterval time.Duration
 
-	expvarAddress string
-
 	Logger *log.Logger
 }
 
@@ -51,7 +48,6 @@ func NewService(c Config) *Service {
 		storeDatabase: c.StoreDatabase,
 		storeAddress:  c.StoreAddress,
 		storeInterval: time.Duration(c.StoreInterval),
-		expvarAddress: c.ExpvarAddress,
 		Logger:        log.New(os.Stderr, "[monitor] ", log.LstdFlags),
 	}
 }
@@ -82,18 +78,6 @@ func (s *Service) Open(clusterID, nodeID uint64, hostname string) error {
 		go s.storeStatistics()
 	}
 
-	// If enabled, expose all expvar data over HTTP.
-	if s.expvarAddress != "" {
-		listener, err := net.Listen("tcp", s.expvarAddress)
-		if err != nil {
-			return err
-		}
-
-		go func() {
-			http.Serve(listener, nil)
-		}()
-		s.Logger.Printf("expvar information available on %s", s.expvarAddress)
-	}
 	return nil
 }
 

services/httpd/handler.go

@@ -5,6 +5,7 @@ import (
 	"compress/gzip"
 	"encoding/json"
 	"errors"
+	"expvar"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -161,10 +162,11 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		default:
 			pprof.Index(w, r)
 		}
-		return
+	} else if strings.HasPrefix(r.URL.Path, "/debug/vars") {
+		serveExpvar(w, r)
+	} else {
+		h.mux.ServeHTTP(w, r)
 	}
-
-	h.mux.ServeHTTP(w, r)
 }
 
 func (h *Handler) serveProcessContinuousQueries(w http.ResponseWriter, r *http.Request, user *meta.UserInfo) {
@@ -569,6 +571,21 @@ type Batch struct {
 	Points          []Point `json:"points"`
 }
 
+// serveExpvar serves registered expvar information over HTTP.
+func serveExpvar(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	fmt.Fprintf(w, "{\n")
+	first := true
+	expvar.Do(func(kv expvar.KeyValue) {
+		if !first {
+			fmt.Fprintf(w, ",\n")
+		}
+		first = false
+		fmt.Fprintf(w, "%q: %s", kv.Key, kv.Value)
+	})
+	fmt.Fprintf(w, "\n}\n")
+}
+
 // httpError writes an error to the client in a standard format.
 func httpError(w http.ResponseWriter, error string, pretty bool, code int) {
 	w.Header().Add("content-type", "application/json")