add vanity url code

2026-01-11 10:34:27 +00:00 · 2021-09-14 14:31:31 +01:00
parent 0fe1baa576
commit 8b37b56cb3
8 changed files with 958 additions and 0 deletions
--- a/cmd/m3o-go-url/LICENSE
+++ b/cmd/m3o-go-url/LICENSE
@@ -0,0 +1,201 @@
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--- a/cmd/m3o-go-url/README.md
+++ b/cmd/m3o-go-url/README.md
@@ -0,0 +1,134 @@
+# M3O Go Vanity URL
+
+M3O Go Vanity URL is a simple Go server that sets the custom url `go.m3o.com`
+
+## Quickstart
+
+Install and run the binary:
+
+```
+$ go get -u github.com/m3o-go/cmd/m3o-go-url
+$ # update vanity.yaml
+$ m3o-go-url
+$ # open http://localhost:8080
+```
+
+### Google App Engine
+
+Install [gcloud](https://cloud.google.com/sdk/downloads) and install Go App Engine component:
+
+```
+$ gcloud components install app-engine-go
+```
+
+Setup a [custom domain](https://cloud.google.com/appengine/docs/standard/python/using-custom-domains-and-ssl) for your app.
+
+Get the application:
+```
+git clone https://github.com/GoogleCloudPlatform/govanityurls
+cd govanityurls
+```
+
+Edit `vanity.yaml` to add any number of git repos. E.g., `customdomain.com/portmidi` will
+serve the [https://github.com/rakyll/portmidi](https://github.com/rakyll/portmidi) repo.
+
+```
+paths:
+  /portmidi:
+    repo: https://github.com/rakyll/portmidi
+```
+
+You can add as many rules as you wish.
+
+Deploy the app:
+
+```
+$ gcloud app deploy
+```
+
+That's it! You can use `go get` to get the package from your custom domain.
+
+```
+$ go get customdomain.com/portmidi
+```
+
+### Running in other environments
+
+You can also deploy this as an App Engine Flexible app by changing the
+`app.yaml` file:
+
+```
+runtime: go
+env: flex
+```
+
+This project is a normal Go HTTP server, so you can also incorporate the
+handler into larger Go servers.
+
+## Configuration File
+
+```
+host: example.com
+cache_max_age: 3600
+paths:
+  /foo:
+    repo: https://github.com/example/foo
+    display: "https://github.com/example/foo https://github.com/example/foo/tree/master{/dir} https://github.com/example/foo/blob/master{/dir}/{file}#L{line}"
+    vcs: git
+```
+
+<table>
+  <thead>
+    <tr>
+      <th scope="col">Key</th>
+      <th scope="col">Required</th>
+      <th scope="col">Description</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <th scope="row"><code>cache_max_age</code></th>
+      <td>optional</td>
+      <td>The amount of time to cache package pages in seconds.  Controls the <code>max-age</code> directive sent in the <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control"><code>Cache-Control</code></a> HTTP header.</td>
+    </tr>
+    <tr>
+      <th scope="row"><code>host</code></th>
+      <td>optional</td>
+      <td>Host name to use in meta tags.  If omitted, uses the App Engine default version host or the Host header on non-App Engine Standard environments.  You can use this option to fix the host when using this service behind a reverse proxy or a <a href="https://cloud.google.com/appengine/docs/standard/go/how-requests-are-routed#routing_with_a_dispatch_file">custom dispatch file</a>.</td>
+    </tr>
+    <tr>
+      <th scope="row"><code>paths</code></th>
+      <td>required</td>
+      <td>Map of paths to path configurations.  Each key is a path that will point to the root of a repository hosted elsewhere.  The fields are documented in the Path Configuration section below.</td>
+    </tr>
+  </tbody>
+</table>
+
+### Path Configuration
+
+<table>
+  <thead>
+    <tr>
+      <th scope="col">Key</th>
+      <th scope="col">Required</th>
+      <th scope="col">Description</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <th scope="row"><code>display</code></th>
+      <td>optional</td>
+      <td>The last three fields of the <a href="https://github.com/golang/gddo/wiki/Source-Code-Links"><code>go-source</code> meta tag</a>.  If omitted, it is inferred from the code hosting service if possible.</td>
+    </tr>
+    <tr>
+      <th scope="row"><code>repo</code></th>
+      <td>required</td>
+      <td>Root URL of the repository as it would appear in <a href="https://golang.org/cmd/go/#hdr-Remote_import_paths"><code>go-import</code> meta tag</a>.</td>
+    </tr>
+    <tr>
+      <th scope="row"><code>vcs</code></th>
+      <td>required if ambiguous</td>
+      <td>If the version control system cannot be inferred (e.g. for Bitbucket or a custom domain), then this specifies the version control system as it would appear in <a href="https://golang.org/cmd/go/#hdr-Remote_import_paths"><code>go-import</code> meta tag</a>.  This can be one of <code>git</code>, <code>hg</code>, <code>svn</code>, or <code>bzr</code>.</td>
+    </tr>
+  </tbody>
+</table>
--- a/cmd/m3o-go-url/go.mod
+++ b/cmd/m3o-go-url/go.mod
@@ -0,0 +1,10 @@
+module github.com/m3o-go/cmd/m3o-go-url
+
+go 1.13
+
+require (
+	github.com/golang/protobuf v1.3.3 // indirect
+	golang.org/x/net v0.0.0-20200202094626-16171245cfb2 // indirect
+	google.golang.org/appengine v1.6.5
+	gopkg.in/yaml.v2 v2.2.8
+)
--- a/cmd/m3o-go-url/go.sum
+++ b/cmd/m3o-go-url/go.sum
@@ -0,0 +1,13 @@
+github.com/golang/protobuf v1.3.1/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/golang/protobuf v1.3.3/go.mod h1:vzj43D7+SQXF/4pzW/hwtAqwc6iTitCiVSaWz5lYuqw=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20190603091049-60506f45cf65/go.mod h1:HSz+uSET+XFnRR8LxR5pz3Of3rY3CfYBVs4xY44aLks=
+golang.org/x/net v0.0.0-20200202094626-16171245cfb2/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+google.golang.org/appengine v1.6.5/go.mod h1:8WjMMxjGQR8xUklV/ARdw2HLXBOI7O7uCIDZVag1xfc=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.8 h1:obN1ZagJSUGI0Ek/LBmuj4SNLPfIny3KsKFopxRdj10=
+gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
--- a/cmd/m3o-go-url/handler.go
+++ b/cmd/m3o-go-url/handler.go
@@ -0,0 +1,225 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// 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.
+
+// govanityurls serves Go vanity URLs.
+package main
+
+import (
+	"errors"
+	"fmt"
+	"html/template"
+	"net/http"
+	"sort"
+	"strings"
+
+	"gopkg.in/yaml.v2"
+)
+
+type handler struct {
+	host         string
+	cacheControl string
+	paths        pathConfigSet
+}
+
+type pathConfig struct {
+	path    string
+	repo    string
+	display string
+	vcs     string
+}
+
+func newHandler(config []byte) (*handler, error) {
+	var parsed struct {
+		Host     string `yaml:"host,omitempty"`
+		CacheAge *int64 `yaml:"cache_max_age,omitempty"`
+		Paths    map[string]struct {
+			Repo    string `yaml:"repo,omitempty"`
+			Display string `yaml:"display,omitempty"`
+			VCS     string `yaml:"vcs,omitempty"`
+		} `yaml:"paths,omitempty"`
+	}
+	if err := yaml.Unmarshal(config, &parsed); err != nil {
+		return nil, err
+	}
+	h := &handler{host: parsed.Host}
+	cacheAge := int64(86400) // 24 hours (in seconds)
+	if parsed.CacheAge != nil {
+		cacheAge = *parsed.CacheAge
+		if cacheAge < 0 {
+			return nil, errors.New("cache_max_age is negative")
+		}
+	}
+	h.cacheControl = fmt.Sprintf("public, max-age=%d", cacheAge)
+	for path, e := range parsed.Paths {
+		pc := pathConfig{
+			path:    strings.TrimSuffix(path, "/"),
+			repo:    e.Repo,
+			display: e.Display,
+			vcs:     e.VCS,
+		}
+		switch {
+		case e.Display != "":
+			// Already filled in.
+		case strings.HasPrefix(e.Repo, "https://github.com/"):
+			pc.display = fmt.Sprintf("%v %v/tree/master{/dir} %v/blob/master{/dir}/{file}#L{line}", e.Repo, e.Repo, e.Repo)
+		case strings.HasPrefix(e.Repo, "https://bitbucket.org"):
+			pc.display = fmt.Sprintf("%v %v/src/default{/dir} %v/src/default{/dir}/{file}#{file}-{line}", e.Repo, e.Repo, e.Repo)
+		}
+		switch {
+		case e.VCS != "":
+			// Already filled in.
+			if e.VCS != "bzr" && e.VCS != "git" && e.VCS != "hg" && e.VCS != "svn" {
+				return nil, fmt.Errorf("configuration for %v: unknown VCS %s", path, e.VCS)
+			}
+		case strings.HasPrefix(e.Repo, "https://github.com/"):
+			pc.vcs = "git"
+		default:
+			return nil, fmt.Errorf("configuration for %v: cannot infer VCS from %s", path, e.Repo)
+		}
+		h.paths = append(h.paths, pc)
+	}
+	sort.Sort(h.paths)
+	return h, nil
+}
+
+func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	current := r.URL.Path
+	pc, subpath := h.paths.find(current)
+	if pc == nil && current == "/" {
+		h.serveIndex(w, r)
+		return
+	}
+	if pc == nil {
+		http.NotFound(w, r)
+		return
+	}
+
+	w.Header().Set("Cache-Control", h.cacheControl)
+	if err := vanityTmpl.Execute(w, struct {
+		Import  string
+		Subpath string
+		Repo    string
+		Display string
+		VCS     string
+	}{
+		Import:  h.Host(r) + pc.path,
+		Subpath: subpath,
+		Repo:    pc.repo,
+		Display: pc.display,
+		VCS:     pc.vcs,
+	}); err != nil {
+		http.Error(w, "cannot render the page", http.StatusInternalServerError)
+	}
+}
+
+func (h *handler) serveIndex(w http.ResponseWriter, r *http.Request) {
+	host := h.Host(r)
+	handlers := make([]string, len(h.paths))
+	for i, h := range h.paths {
+		handlers[i] = host + h.path
+	}
+	if err := indexTmpl.Execute(w, struct {
+		Host     string
+		Handlers []string
+	}{
+		Host:     host,
+		Handlers: handlers,
+	}); err != nil {
+		http.Error(w, "cannot render the page", http.StatusInternalServerError)
+	}
+}
+
+func (h *handler) Host(r *http.Request) string {
+	host := h.host
+	if host == "" {
+		host = defaultHost(r)
+	}
+	return host
+}
+
+var indexTmpl = template.Must(template.New("index").Parse(`<!DOCTYPE html>
+<html>
+<h1>{{.Host}}</h1>
+<ul>
+{{range .Handlers}}<li><a href="https://pkg.go.dev/{{.}}">{{.}}</a></li>{{end}}
+</ul>
+</html>
+`))
+
+var vanityTmpl = template.Must(template.New("vanity").Parse(`<!DOCTYPE html>
+<html>
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
+<meta name="go-import" content="{{.Import}} {{.VCS}} {{.Repo}}">
+<meta name="go-source" content="{{.Import}} {{.Display}}">
+<meta http-equiv="refresh" content="0; url=https://pkg.go.dev/{{.Import}}/{{.Subpath}}">
+</head>
+<body>
+Nothing to see here; <a href="https://pkg.go.dev/{{.Import}}/{{.Subpath}}">see the package on pkg.go.dev</a>.
+</body>
+</html>`))
+
+type pathConfigSet []pathConfig
+
+func (pset pathConfigSet) Len() int {
+	return len(pset)
+}
+
+func (pset pathConfigSet) Less(i, j int) bool {
+	return pset[i].path < pset[j].path
+}
+
+func (pset pathConfigSet) Swap(i, j int) {
+	pset[i], pset[j] = pset[j], pset[i]
+}
+
+func (pset pathConfigSet) find(path string) (pc *pathConfig, subpath string) {
+	// Fast path with binary search to retrieve exact matches
+	// e.g. given pset ["/", "/abc", "/xyz"], path "/def" won't match.
+	i := sort.Search(len(pset), func(i int) bool {
+		return pset[i].path >= path
+	})
+	if i < len(pset) && pset[i].path == path {
+		return &pset[i], ""
+	}
+	if i > 0 && strings.HasPrefix(path, pset[i-1].path+"/") {
+		return &pset[i-1], path[len(pset[i-1].path)+1:]
+	}
+
+	// Slow path, now looking for the longest prefix/shortest subpath i.e.
+	// e.g. given pset ["/", "/abc/", "/abc/def/", "/xyz"/]
+	//  * query "/abc/foo" returns "/abc/" with a subpath of "foo"
+	//  * query "/x" returns "/" with a subpath of "x"
+	lenShortestSubpath := len(path)
+	var bestMatchConfig *pathConfig
+
+	// After binary search with the >= lexicographic comparison,
+	// nothing greater than i will be a prefix of path.
+	max := i
+	for i := 0; i < max; i++ {
+		ps := pset[i]
+		if len(ps.path) >= len(path) {
+			// We previously didn't find the path by search, so any
+			// route with equal or greater length is NOT a match.
+			continue
+		}
+		sSubpath := strings.TrimPrefix(path, ps.path)
+		if len(sSubpath) < lenShortestSubpath {
+			subpath = sSubpath
+			lenShortestSubpath = len(sSubpath)
+			bestMatchConfig = &pset[i]
+		}
+	}
+	return bestMatchConfig, subpath
+}
--- a/cmd/m3o-go-url/handler_test.go
+++ b/cmd/m3o-go-url/handler_test.go
@@ -0,0 +1,315 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// 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 main
+
+import (
+	"bytes"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"sort"
+	"testing"
+)
+
+func TestHandler(t *testing.T) {
+	tests := []struct {
+		name   string
+		config string
+		path   string
+
+		goImport string
+		goSource string
+	}{
+		{
+			name: "explicit display",
+			config: "host: example.com\n" +
+				"paths:\n" +
+				"  /portmidi:\n" +
+				"    repo: https://github.com/rakyll/portmidi\n" +
+				"    display: https://github.com/rakyll/portmidi _ _\n",
+			path:     "/portmidi",
+			goImport: "example.com/portmidi git https://github.com/rakyll/portmidi",
+			goSource: "example.com/portmidi https://github.com/rakyll/portmidi _ _",
+		},
+		{
+			name: "display GitHub inference",
+			config: "host: example.com\n" +
+				"paths:\n" +
+				"  /portmidi:\n" +
+				"    repo: https://github.com/rakyll/portmidi\n",
+			path:     "/portmidi",
+			goImport: "example.com/portmidi git https://github.com/rakyll/portmidi",
+			goSource: "example.com/portmidi https://github.com/rakyll/portmidi https://github.com/rakyll/portmidi/tree/master{/dir} https://github.com/rakyll/portmidi/blob/master{/dir}/{file}#L{line}",
+		},
+		{
+			name: "Bitbucket Mercurial",
+			config: "host: example.com\n" +
+				"paths:\n" +
+				"  /gopdf:\n" +
+				"    repo: https://bitbucket.org/zombiezen/gopdf\n" +
+				"    vcs: hg\n",
+			path:     "/gopdf",
+			goImport: "example.com/gopdf hg https://bitbucket.org/zombiezen/gopdf",
+			goSource: "example.com/gopdf https://bitbucket.org/zombiezen/gopdf https://bitbucket.org/zombiezen/gopdf/src/default{/dir} https://bitbucket.org/zombiezen/gopdf/src/default{/dir}/{file}#{file}-{line}",
+		},
+		{
+			name: "Bitbucket Git",
+			config: "host: example.com\n" +
+				"paths:\n" +
+				"  /mygit:\n" +
+				"    repo: https://bitbucket.org/zombiezen/mygit\n" +
+				"    vcs: git\n",
+			path:     "/mygit",
+			goImport: "example.com/mygit git https://bitbucket.org/zombiezen/mygit",
+			goSource: "example.com/mygit https://bitbucket.org/zombiezen/mygit https://bitbucket.org/zombiezen/mygit/src/default{/dir} https://bitbucket.org/zombiezen/mygit/src/default{/dir}/{file}#{file}-{line}",
+		},
+		{
+			name: "subpath",
+			config: "host: example.com\n" +
+				"paths:\n" +
+				"  /portmidi:\n" +
+				"    repo: https://github.com/rakyll/portmidi\n" +
+				"    display: https://github.com/rakyll/portmidi _ _\n",
+			path:     "/portmidi/foo",
+			goImport: "example.com/portmidi git https://github.com/rakyll/portmidi",
+			goSource: "example.com/portmidi https://github.com/rakyll/portmidi _ _",
+		},
+		{
+			name: "subpath with trailing config slash",
+			config: "host: example.com\n" +
+				"paths:\n" +
+				"  /portmidi/:\n" +
+				"    repo: https://github.com/rakyll/portmidi\n" +
+				"    display: https://github.com/rakyll/portmidi _ _\n",
+			path:     "/portmidi/foo",
+			goImport: "example.com/portmidi git https://github.com/rakyll/portmidi",
+			goSource: "example.com/portmidi https://github.com/rakyll/portmidi _ _",
+		},
+	}
+	for _, test := range tests {
+		h, err := newHandler([]byte(test.config))
+		if err != nil {
+			t.Errorf("%s: newHandler: %v", test.name, err)
+			continue
+		}
+		s := httptest.NewServer(h)
+		resp, err := http.Get(s.URL + test.path)
+		if err != nil {
+			s.Close()
+			t.Errorf("%s: http.Get: %v", test.name, err)
+			continue
+		}
+		data, err := ioutil.ReadAll(resp.Body)
+		resp.Body.Close()
+		s.Close()
+		if resp.StatusCode != http.StatusOK {
+			t.Errorf("%s: status code = %s; want 200 OK", test.name, resp.Status)
+		}
+		if err != nil {
+			t.Errorf("%s: ioutil.ReadAll: %v", test.name, err)
+			continue
+		}
+		if got := findMeta(data, "go-import"); got != test.goImport {
+			t.Errorf("%s: meta go-import = %q; want %q", test.name, got, test.goImport)
+		}
+		if got := findMeta(data, "go-source"); got != test.goSource {
+			t.Errorf("%s: meta go-source = %q; want %q", test.name, got, test.goSource)
+		}
+	}
+}
+
+func TestBadConfigs(t *testing.T) {
+	badConfigs := []string{
+		"paths:\n" +
+			"  /missingvcs:\n" +
+			"    repo: https://bitbucket.org/zombiezen/gopdf\n",
+		"paths:\n" +
+			"  /unknownvcs:\n" +
+			"    repo: https://bitbucket.org/zombiezen/gopdf\n" +
+			"    vcs: xyzzy\n",
+		"cache_max_age: -1\n" +
+			"paths:\n" +
+			"  /portmidi:\n" +
+			"    repo: https://github.com/rakyll/portmidi\n",
+	}
+	for _, config := range badConfigs {
+		_, err := newHandler([]byte(config))
+		if err == nil {
+			t.Errorf("expected config to produce an error, but did not:\n%s", config)
+		}
+	}
+}
+
+func findMeta(data []byte, name string) string {
+	var sep []byte
+	sep = append(sep, `<meta name="`...)
+	sep = append(sep, name...)
+	sep = append(sep, `" content="`...)
+	i := bytes.Index(data, sep)
+	if i == -1 {
+		return ""
+	}
+	content := data[i+len(sep):]
+	j := bytes.IndexByte(content, '"')
+	if j == -1 {
+		return ""
+	}
+	return string(content[:j])
+}
+
+func TestPathConfigSetFind(t *testing.T) {
+	tests := []struct {
+		paths   []string
+		query   string
+		want    string
+		subpath string
+	}{
+		{
+			paths: []string{"/portmidi"},
+			query: "/portmidi",
+			want:  "/portmidi",
+		},
+		{
+			paths: []string{"/portmidi"},
+			query: "/portmidi/",
+			want:  "/portmidi",
+		},
+		{
+			paths: []string{"/portmidi"},
+			query: "/foo",
+			want:  "",
+		},
+		{
+			paths: []string{"/portmidi"},
+			query: "/zzz",
+			want:  "",
+		},
+		{
+			paths: []string{"/abc", "/portmidi", "/xyz"},
+			query: "/portmidi",
+			want:  "/portmidi",
+		},
+		{
+			paths:   []string{"/abc", "/portmidi", "/xyz"},
+			query:   "/portmidi/foo",
+			want:    "/portmidi",
+			subpath: "foo",
+		},
+		{
+			paths:   []string{"/example/helloworld", "/", "/y", "/foo"},
+			query:   "/x",
+			want:    "/",
+			subpath: "x",
+		},
+		{
+			paths:   []string{"/example/helloworld", "/", "/y", "/foo"},
+			query:   "/",
+			want:    "/",
+			subpath: "",
+		},
+		{
+			paths:   []string{"/example/helloworld", "/", "/y", "/foo"},
+			query:   "/example",
+			want:    "/",
+			subpath: "example",
+		},
+		{
+			paths:   []string{"/example/helloworld", "/", "/y", "/foo"},
+			query:   "/example/foo",
+			want:    "/",
+			subpath: "example/foo",
+		},
+		{
+			paths: []string{"/example/helloworld", "/", "/y", "/foo"},
+			query: "/y",
+			want:  "/y",
+		},
+		{
+			paths:   []string{"/example/helloworld", "/", "/y", "/foo"},
+			query:   "/x/y/",
+			want:    "/",
+			subpath: "x/y/",
+		},
+		{
+			paths: []string{"/example/helloworld", "/y", "/foo"},
+			query: "/x",
+			want:  "",
+		},
+	}
+	emptyToNil := func(s string) string {
+		if s == "" {
+			return "<nil>"
+		}
+		return s
+	}
+	for _, test := range tests {
+		pset := make(pathConfigSet, len(test.paths))
+		for i := range test.paths {
+			pset[i].path = test.paths[i]
+		}
+		sort.Sort(pset)
+		pc, subpath := pset.find(test.query)
+		var got string
+		if pc != nil {
+			got = pc.path
+		}
+		if got != test.want || subpath != test.subpath {
+			t.Errorf("pathConfigSet(%v).find(%q) = %v, %v; want %v, %v",
+				test.paths, test.query, emptyToNil(got), subpath, emptyToNil(test.want), test.subpath)
+		}
+	}
+}
+
+func TestCacheHeader(t *testing.T) {
+	tests := []struct {
+		name         string
+		config       string
+		cacheControl string
+	}{
+		{
+			name:         "default",
+			cacheControl: "public, max-age=86400",
+		},
+		{
+			name:         "specify time",
+			config:       "cache_max_age: 60\n",
+			cacheControl: "public, max-age=60",
+		},
+		{
+			name:         "zero",
+			config:       "cache_max_age: 0\n",
+			cacheControl: "public, max-age=0",
+		},
+	}
+	for _, test := range tests {
+		h, err := newHandler([]byte("paths:\n  /portmidi:\n    repo: https://github.com/rakyll/portmidi\n" +
+			test.config))
+		if err != nil {
+			t.Errorf("%s: newHandler: %v", test.name, err)
+			continue
+		}
+		s := httptest.NewServer(h)
+		resp, err := http.Get(s.URL + "/portmidi")
+		if err != nil {
+			t.Errorf("%s: http.Get: %v", test.name, err)
+			continue
+		}
+		resp.Body.Close()
+		got := resp.Header.Get("Cache-Control")
+		if got != test.cacheControl {
+			t.Errorf("%s: Cache-Control header = %q; want %q", test.name, got, test.cacheControl)
+		}
+	}
+}
--- a/cmd/m3o-go-url/main.go
+++ b/cmd/m3o-go-url/main.go
@@ -0,0 +1,55 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// 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 main
+
+import (
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+)
+
+func main() {
+	var configPath string
+	switch len(os.Args) {
+	case 1:
+		configPath = "vanity.yaml"
+	case 2:
+		configPath = os.Args[1]
+	default:
+		log.Fatal("usage: m3o-go-url [CONFIG]")
+	}
+	vanity, err := ioutil.ReadFile(configPath)
+	if err != nil {
+		log.Fatal(err)
+	}
+	h, err := newHandler(vanity)
+	if err != nil {
+		log.Fatal(err)
+	}
+	http.Handle("/", h)
+
+	port := os.Getenv("PORT")
+	if port == "" {
+		port = "8080"
+	}
+	if err := http.ListenAndServe(":"+port, nil); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func defaultHost(r *http.Request) string {
+	return r.Host
+}
--- a/cmd/m3o-go-url/vanity.yaml
+++ b/cmd/m3o-go-url/vanity.yaml
@@ -0,0 +1,5 @@
+host: go.m3o.com
+
+paths:
+  /:
+    repo: https://github.com/m3o/m3o-go