Fix the Route Prefix bug and add ExternalURL Support (#190)

handler/misc.go

@@ -63,9 +63,17 @@ func Ready(ms storage.MetricStore) http.Handler {
 // Static serves the static files from the provided http.FileSystem.
 //
 // The returned handler is already instrumented for Prometheus.
-func Static(root http.FileSystem) http.Handler {
+func Static(root http.FileSystem, prefix string) http.Handler {
+	if prefix == "/" {
+		prefix = ""
+	}
+
+	handler := http.FileServer(root)
 	return promhttp.InstrumentHandlerCounter(
 		httpCnt.MustCurryWith(prometheus.Labels{"handler": "static"}),
-		http.FileServer(root),
+		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			r.URL.Path = r.URL.Path[len(prefix):]
+			handler.ServeHTTP(w, r)
+		}),
 	)
 }

handler/misc_test.go

@@ -0,0 +1,75 @@
+// Copyright 2019 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package handler
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+)
+
+type fakeFileSystem struct {
+	files map[string]struct{}
+}
+
+// Open implements the http.FileSystem interface
+//
+// If a file is present, no error will be returned.
+// This implementation always returns a nil File.
+func (f *fakeFileSystem) Open(name string) (http.File, error) {
+	log.Println("requesting" + name)
+
+	if _, ok := f.files[name]; !ok {
+		return nil, os.ErrNotExist
+	}
+	return os.Open("misc_test.go")
+	//	return nil, nil
+}
+
+func TestRoutePrefixForStatic(t *testing.T) {
+	fs := &fakeFileSystem{map[string]struct{}{
+		"/index.js": struct{}{},
+	}}
+
+	for _, test := range []struct {
+		prefix string
+		path   string
+		code   int
+	}{
+		{"/", "/index.js", 200},
+		{"/", "/missing.js", 404},
+		{"/route-prefix", "/index.js", 200},
+		{"/route-prefix", "/missing.js", 404},
+	} {
+		test := test
+		t.Run(fmt.Sprintf("%v", test), func(t *testing.T) {
+			t.Parallel()
+			req, err := http.NewRequest(
+				http.MethodGet, "http://example.com"+test.prefix+test.path, nil,
+			)
+			if err != nil {
+				t.Fatal(err)
+			}
+			w := httptest.NewRecorder()
+			static := Static(fs, test.prefix)
+			static.ServeHTTP(w, req)
+			if test.code != w.Code {
+				t.Errorf("Wanted %d, got %d.", test.code, w.Code)
+			}
+		})
+	}
+}

handler/status.go

@@ -19,6 +19,7 @@ import (
 	"html/template"
 	"io/ioutil"
 	"net/http"
+	"path"
 	"strconv"
 	"time"
 
@@ -36,6 +37,7 @@ type data struct {
 	Flags        map[string]string
 	BuildInfo    map[string]string
 	Birth        time.Time
+	BaseURL      string
 	counter      int
 }
 
@@ -66,6 +68,11 @@ func Status(
 					return strconv.FormatFloat(f, 'f', -1, 64)
 				},
 			})
+
+			externalURL := flags["web.external-url"]
+			routePrefix := flags["web.route-prefix"]
+			baseURL := path.Join(externalURL, routePrefix)
+
 			f, err := root.Open("template.html")
 			if err != nil {
 				http.Error(w, err.Error(), http.StatusInternalServerError)
@@ -99,6 +106,7 @@ func Status(
 				MetricGroups: ms.GetMetricFamiliesMap(),
 				BuildInfo:    buildInfo,
 				Birth:        birth,
+				BaseURL:      baseURL,
 			}
 			d.Flags = map[string]string{}
 			// Exclude kingpin default flags to expose only Prometheus ones.

handler/status_test.go

@@ -0,0 +1,52 @@
+// Copyright 2019 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package handler
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/prometheus/pushgateway/asset"
+	"github.com/prometheus/pushgateway/storage"
+)
+
+func TestExternalURLPresenceInPage(t *testing.T) {
+	flags := map[string]string{
+		"web.listen-address": ":9091",
+		"web.telemetry-path": "/metrics",
+		"web.external-url":   "http://web-external-url.com",
+	}
+
+	ms := storage.NewDiskMetricStore("", time.Minute, nil)
+	status := Status(ms, asset.Assets, flags)
+	defer ms.Shutdown()
+
+	w := httptest.NewRecorder()
+	status.ServeHTTP(w, &http.Request{})
+
+	if http.StatusOK != w.Code {
+		t.Fatalf("Wanted status %d, got %d", http.StatusOK, w.Code)
+	}
+
+	var rawBody []byte
+	w.Result().Body.Read(rawBody)
+	body := string(rawBody)
+
+	if index := strings.Index(body, flags["web.external-url"]); index > 0 {
+		t.Errorf("Wanted index of %q > 0 , got %d", flags["web.external-url"], index)
+	}
+}

main.go

@@ -17,6 +17,7 @@ import (
 	"net"
 	"net/http"
 	"net/http/pprof"
+	"net/url"
 	"os"
 	"os/signal"
 	"path"
@@ -49,7 +50,8 @@ func main() {
 
 		listenAddress       = app.Flag("web.listen-address", "Address to listen on for the web interface, API, and telemetry.").Default(":9091").String()
 		metricsPath         = app.Flag("web.telemetry-path", "Path under which to expose metrics.").Default("/metrics").String()
-		routePrefix         = app.Flag("web.route-prefix", "Prefix for the internal routes of web endpoints.").Default("").String()
+		externalURL         = app.Flag("web.external-url", "The URL under which the Pushgateway is externally reachable.").Default("").URL()
+		routePrefix         = app.Flag("web.route-prefix", "Prefix for the internal routes of web endpoints. Defaults to the path of --web.external-url.").Default("").String()
 		persistenceFile     = app.Flag("persistence.file", "File to persist metrics. If empty, metrics are only kept in memory.").Default("").String()
 		persistenceInterval = app.Flag("persistence.interval", "The minimum interval at which to write out the persistence file.").Default("5m").Duration()
 	)
@@ -58,16 +60,14 @@ func main() {
 	app.HelpFlag.Short('h')
 	kingpin.MustParse(app.Parse(os.Args[1:]))
 
-	if *routePrefix == "/" {
-		*routePrefix = ""
-	}
-	if *routePrefix != "" {
-		*routePrefix = "/" + strings.Trim(*routePrefix, "/")
-	}
+	*routePrefix = computeRoutePrefix(*routePrefix, *externalURL)
 
 	log.Infoln("Starting pushgateway", version.Info())
 	log.Infoln("Build context", version.BuildContext())
 	log.Debugf("Prefix path is '%s'", *routePrefix)
+	log.Debugf("External URL is '%s'", *externalURL)
+
+	(*externalURL).Path = ""
 
 	flags := map[string]string{}
 	for _, f := range app.Model().Flags {
@@ -96,7 +96,7 @@ func main() {
 	r.POST(pushAPIPath+"/job/:job", handler.Push(ms, false))
 	r.DELETE(pushAPIPath+"/job/:job", handler.Delete(ms))
 
-	r.Handler("GET", *routePrefix+"/static/*filepath", handler.Static(asset.Assets))
+	r.Handler("GET", *routePrefix+"/static/*filepath", handler.Static(asset.Assets, *routePrefix))
 
 	statusHandler := handler.Status(ms, asset.Assets, flags)
 	r.Handler("GET", *routePrefix+"/status", statusHandler)
@@ -135,6 +135,27 @@ func handlePprof(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
 	}
 }
 
+// computeRoutePrefix returns the effective route prefix based on the
+// provided flag values for --web.route-prefix and
+// --web.external-url. With prefix empty, the path of externalURL is
+// used instead. A prefix "/" results in an empty returned prefix. Any
+// non-empty prefix is normalized to start, but not to end, with "/".
+func computeRoutePrefix(prefix string, externalURL *url.URL) string {
+	if prefix == "" {
+		prefix = externalURL.Path
+	}
+
+	if prefix == "/" {
+		prefix = ""
+	}
+
+	if prefix != "" {
+		prefix = "/" + strings.Trim(prefix, "/")
+	}
+
+	return prefix
+}
+
 func interruptHandler(l net.Listener) {
 	notifier := make(chan os.Signal, 1)
 	signal.Notify(notifier, os.Interrupt, syscall.SIGTERM)

resources/template.html

@@ -19,12 +19,11 @@
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <title>Prometheus Pushgateway</title>
 
-    {{- $prefix := index .Flags "web.route-prefix" }}
-    <script src="{{$prefix}}/static/jquery-2.1.4.min.js"></script>
-    <link rel="stylesheet" href="{{$prefix}}/static/bootstrap-3.3.4-dist/css/bootstrap.min.css">
-    <link rel="stylesheet" href="{{$prefix}}/static/bootstrap-3.3.4-dist/css/bootstrap-theme.min.css">
-    <script src="{{$prefix}}/static/bootstrap-3.3.4-dist/js/bootstrap.min.js"></script>
-    <script src="{{$prefix}}/static/functions.js"></script>
+    <script src="{{.BaseURL}}/static/jquery-2.1.4.min.js"></script>
+    <link rel="stylesheet" href="{{.BaseURL}}/static/bootstrap-3.3.4-dist/css/bootstrap.min.css">
+    <link rel="stylesheet" href="{{.BaseURL}}/static/bootstrap-3.3.4-dist/css/bootstrap-theme.min.css">
+    <script src="{{.BaseURL}}/static/bootstrap-3.3.4-dist/js/bootstrap.min.js"></script>
+    <script src="{{.BaseURL}}/static/functions.js"></script>
 
     <style type="text/css">
       .cursor-pointer {
@@ -244,6 +243,6 @@ <h3 id="del-header">Deletion Confirmation</h3>
       </div>
     </div>
   </div>
-  
+
 </body>
 </html>