feat(gateway): improved templates, user friendly errors

CHANGELOG.md

@@ -14,6 +14,11 @@ The following emojis are used to highlight certain changes:
 
 ## [Unreleased]
 
+- ✨ The gateway templates were updated to provide better features for users and gateway implementers:
+  - New human-friendly error messages.
+  - Updated, higher-definition icons in directory listings.
+  - Customizable menu items next to "About IPFS" and "Install IPFS".
+
 ## [0.8.0] - 2023-04-05
 ### Added
 

examples/gateway/common/handler.go

@@ -4,6 +4,7 @@ import (
 	"net/http"
 
 	"github.com/ipfs/boxo/gateway"
+	"github.com/ipfs/boxo/gateway/assets"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
@@ -16,6 +17,12 @@ func NewHandler(gwAPI gateway.IPFSBackend) http.Handler {
 	gateway.AddAccessControlHeaders(headers)
 	conf := gateway.Config{
 		Headers: headers,
+		Menu: []assets.MenuItem{
+			{
+				URL:   "https://github.com/ipfs/boxo",
+				Title: "Boxo",
+			},
+		},
 	}
 
 	// Initialize the public gateways that we will want to have available through

gateway/assets/README.md

@@ -1,27 +1,20 @@
 # Required Assets for the Gateway
 
-> DAG and Directory HTML for HTTP gateway
+> HTTP Gateway Templates.
 
 ## Updating
 
-When making updates to the templates, please note the following:
-
-1. Make your changes to the (human-friendly) source documents in the `src` directory.
-2. Before testing or releasing, go to `assets/` and run `go generate .`.
+To update the templates, make changes to the files in `html/` and `css/`.
 
 ## Testing
 
-1. Make sure you have [Go](https://golang.org/dl/) installed
-2. Start the test server, which lives in its own directory:
-
-```bash
-> cd test
-> go run .
-```
+1. Make sure you have [Go](https://golang.org/dl/) installed.
+2. From the `assets/` directory, start the test server: `go run test/main.go`.
 
-This will listen on [`localhost:3000`](http://localhost:3000/) and reload the template every time you refresh the page. Here you have two pages:
+This will listen on [`localhost:3000`](http://localhost:3000/) and reload the template every time you refresh the page. Here you have three pages:
 
 - [`localhost:3000/dag`](http://localhost:3000/dag) for the DAG template preview; and
-- [`localhost:3000/directory`](http://localhost:3000/directory) for the Directory template preview.
+- [`localhost:3000/directory`](http://localhost:3000/directory) for the Directory template preview; and
+- [`localhost:3000/error?code=500`](http://localhost:3000/error?status=500) for the Error template preview, you can replace `500` by a different status code.
 
-If you get a "no such file or directory" error upon trying `go run .`, make sure you ran `go generate .` to generate the minified artifact that the test is looking for.
+Every time you refresh, the template will be reloaded.

gateway/assets/assets.go

@@ -1,4 +1,3 @@
-//go:generate ./build.sh
 package assets
 
 import (
@@ -9,24 +8,23 @@ import (
 	"strconv"
 
 	"html/template"
-	"net/url"
-	"path"
 	"strings"
 
 	"github.com/cespare/xxhash/v2"
 
 	ipfspath "github.com/ipfs/boxo/path"
 )
 
-//go:embed dag-index.html directory-index.html knownIcons.txt
-var asset embed.FS
+//go:embed *.html *.css
+var assets embed.FS
 
 // AssetHash a non-cryptographic hash of all embedded assets
 var AssetHash string
 
 var (
 	DirectoryTemplate *template.Template
 	DagTemplate       *template.Template
+	ErrorTemplate     *template.Template
 )
 
 func init() {
@@ -36,7 +34,7 @@ func init() {
 
 func initAssetsHash() {
 	sum := xxhash.New()
-	err := fs.WalkDir(asset, ".", func(path string, d fs.DirEntry, err error) error {
+	err := fs.WalkDir(assets, ".", func(path string, d fs.DirEntry, err error) error {
 		if err != nil {
 			return err
 		}
@@ -45,7 +43,7 @@ func initAssetsHash() {
 			return nil
 		}
 
-		file, err := asset.Open(path)
+		file, err := assets.Open(path)
 		if err != nil {
 			return err
 		}
@@ -61,60 +59,53 @@ func initAssetsHash() {
 }
 
 func initTemplates() {
-	knownIconsBytes, err := asset.ReadFile("knownIcons.txt")
+	var err error
+
+	// Directory listing template
+	DirectoryTemplate, err = BuildTemplate(assets, "directory.html")
 	if err != nil {
 		panic(err)
 	}
-	knownIcons := make(map[string]struct{})
-	for _, ext := range strings.Split(strings.TrimSuffix(string(knownIconsBytes), "\n"), "\n") {
-		knownIcons[ext] = struct{}{}
-	}
 
-	// helper to guess the type/icon for it by the extension name
-	iconFromExt := func(name string) string {
-		ext := path.Ext(name)
-		_, ok := knownIcons[ext]
-		if !ok {
-			// default blank icon
-			return "ipfs-_blank"
-		}
-		return "ipfs-" + ext[1:] // slice of the first dot
-	}
-
-	// custom template-escaping function to escape a full path, including '#' and '?'
-	urlEscape := func(rawUrl string) string {
-		pathURL := url.URL{Path: rawUrl}
-		return pathURL.String()
-	}
-
-	// Directory listing template
-	dirIndexBytes, err := asset.ReadFile("directory-index.html")
+	// DAG Index template
+	DagTemplate, err = BuildTemplate(assets, "dag.html")
 	if err != nil {
 		panic(err)
 	}
 
-	DirectoryTemplate = template.Must(template.New("dir").Funcs(template.FuncMap{
-		"iconFromExt": iconFromExt,
-		"urlEscape":   urlEscape,
-	}).Parse(string(dirIndexBytes)))
-
-	// DAG Index template
-	dagIndexBytes, err := asset.ReadFile("dag-index.html")
+	// Error template
+	ErrorTemplate, err = BuildTemplate(assets, "error.html")
 	if err != nil {
 		panic(err)
 	}
+}
 
-	DagTemplate = template.Must(template.New("dir").Parse(string(dagIndexBytes)))
+type MenuItem struct {
+	URL   string
+	Title string
+}
+
+type GlobalData struct {
+	Menu []MenuItem
 }
 
 type DagTemplateData struct {
+	GlobalData
 	Path      string
 	CID       string
 	CodecName string
 	CodecHex  string
 }
 
+type ErrorTemplateData struct {
+	GlobalData
+	StatusCode int
+	StatusText string
+	Error      string
+}
+
 type DirectoryTemplateData struct {
+	GlobalData
 	GatewayURL  string
 	DNSLink     bool
 	Listing     []DirectoryItem

gateway/assets/dag.html

@@ -0,0 +1,33 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="utf-8" />
+  <meta name="description" content="A DAG hosted on IPFS: {{ .Path }}.">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <link rel="shortcut icon" href="data:image/x-icon;base64,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" />
+  <title>{{ .Path }}</title>
+  <link rel="stylesheet">
+</head>
+<body>
+  <header></header>
+  <main id="main">
+    <header>
+      <div>
+        <strong>CID: <code translate="no">{{.CID}}</code></strong>
+      </div>
+      <div>
+        <strong>Codec</strong>: <code translate="no">{{.CodecName}} ({{.CodecHex}})</code>
+      </div>
+    </header>
+    <section class="container">
+      <p>You can download this block as:</p>
+
+      <ul>
+        <li><a href="?format=raw" rel="nofollow">Raw Block</a> (no conversion)</li>
+        <li><a href="?format=dag-json" rel="nofollow">Valid DAG-JSON</a> (specs at <a href="https://ipld.io/specs/codecs/dag-json/spec/" target="_blank" rel="noopener noreferrer">IPLD</a> and <a href="https://www.iana.org/assignments/media-types/application/vnd.ipld.dag-json" target="_blank" rel="noopener noreferrer">IANA</a>)</li>
+        <li><a href="?format=dag-cbor" rel="nofollow">Valid DAG-CBOR</a> (specs at <a href="https://ipld.io/specs/codecs/dag-cbor/spec/" target="_blank" rel="noopener noreferrer">IPLD</a> and <a href="https://www.iana.org/assignments/media-types/application/vnd.ipld.dag-cbor" target="_blank" rel="noopener noreferrer">IANA</a>)</li>
+      </ul>
+    </section>
+  </main>
+</body>
+</html>

gateway/assets/directory.html

@@ -0,0 +1,70 @@
+<!DOCTYPE html>
+{{ $root := . }}
+<html lang="en">
+<head>
+  <meta charset="utf-8" />
+  <meta name="description" content="A directory of content-addressed files hosted on IPFS.">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <link rel="shortcut icon" href="data:image/x-icon;base64,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" />
+  <title>{{ .Path }}</title>
+  <link rel="stylesheet">
+</head>
+<body>
+  <header></header>
+  <main id="main">
+    <header class="flex flex-wrap">
+      <div>
+        <strong>
+          Index of
+          {{ range .Breadcrumbs -}}
+          /{{ if .Path }}<a href="{{ $root.GatewayURL }}{{ .Path | urlEscape }}">{{ .Name }}</a>{{ else }}{{ .Name }}{{ end }}
+          {{- else }}
+          {{ .Path }}
+          {{ end }}
+        </strong>
+        {{ if .Hash }}
+        <div class="ipfs-hash" translate="no">
+          {{- .Hash -}}
+        </div>
+        {{ end }}
+      </div>
+      {{ if .Size }}
+      <div class="nowrap flex-shrink ml-auto">
+        <strong title="Cumulative size of IPFS DAG (data + metadata)">&nbsp;{{ .Size }}</strong>
+      </div>
+      {{ end }}
+    </header>
+    <section>
+      <div class="grid dir">
+        {{ if .BackLink }}
+          <div class="type-icon">
+            <div class="ipfs-_blank">&nbsp;</div>
+          </div>
+          <div>
+            <a href="{{.BackLink | urlEscape}}">..</a>
+          </div>
+          <div></div>
+          <div></div>
+        </tr>
+        {{ end }}
+        {{ range .Listing }}
+          <div class="type-icon">
+            <div class="{{iconFromExt .Name}}">&nbsp;</div>
+          </div>
+          <div>
+            <a href="{{ .Path | urlEscape }}">{{ .Name }}</a>
+          </div>
+          <div class="nowrap">
+            {{ if .Hash }}
+            <a class="ipfs-hash" translate="no" href={{ if $root.DNSLink }}"https://cid.ipfs.tech/#{{ .Hash | urlEscape}}" target="_blank" rel="noreferrer noopener"{{ else }}"{{ $root.GatewayURL }}/ipfs/{{ .Hash | urlEscape}}?filename={{ .Name | urlEscape }}"{{ end }}>
+              {{- .ShortHash -}}
+            </a>
+            {{ end }}
+          </div>
+          <div class="nowrap" title="Cumulative size of IPFS DAG (data + metadata)">{{ .Size }}</div>
+        {{ end }}
+      </div>
+    </section>
+  </main>
+</body>
+</html>

gateway/assets/error.html

@@ -0,0 +1,54 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="utf-8" />
+  <meta name="description" content="A {{ .StatusCode }} {{ .StatusText }} error has occurred when trying to fetch content from the IPFS network.">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <link rel="shortcut icon" href="data:image/x-icon;base64,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" />
+  <title>{{ .StatusCode }} {{ .StatusText }}</title>
+  <link rel="stylesheet">
+</head>
+<body>
+  <header></header>
+  <main id="main">
+    <header>
+      <strong>{{ .StatusCode }} {{ .StatusText }}</strong>
+    </header>
+    <section class="container">
+      {{ if eq .StatusCode 400 }}
+        <p>Your request is invalid. Please check the error below for more information.</p>
+      {{ else if eq .StatusCode 404 }}
+        <p>The content path you requested cannot be found. There's likely an invalid or missing DAG node.</p>
+      {{ else if eq .StatusCode 406 }}
+        <p>This gateway is unable to return the data in the format requested by the client.</p>
+      {{ else if eq .StatusCode 410 }}
+        <p>This gateway refuses to return the requested data.</p>
+      {{ else if eq .StatusCode 412 }}
+        <p>This gateway is unable to return the requested data under the conditions sent by the client.</p>
+      {{ else if eq .StatusCode 429 }}
+        <p>You have made too many requests. Please wait some time and try again.</p>
+      {{ else if eq .StatusCode 451 }}
+        <p>This gateway is not allowed to return the requested data due to legal reasons.</p>
+      {{ else if eq .StatusCode 500 }}
+        <p>This gateway was unable to return the requested data due to an internal error. Please check the error below for more information.</p>
+      {{ else if eq .StatusCode 502 }}
+        <p>The gateway backed was unable to fullfil your request due to an error.</p>
+      {{ else if eq .StatusCode 504 }}
+        <p>The gateway backend was unable to fullfil your request due to a timeout.</p>
+      {{ end }}
+
+      <pre class="terminal wrap">{{ .Error }}</pre>
+
+      <p>How you can proceed:</p>
+      <ul>
+        <li>Check the <a href="https://discuss.ipfs.tech/c/help/13" rel="noopener noreferrer">Discussion Forums</a> for similar errors.</li>
+        <li>Try diagnosing your request with the <a href="https://docs.ipfs.tech/reference/diagnostic-tools/" rel="noopener noreferrer">diagnostic tools</a>.</li>
+        <li>Self-host and run an <a href="https://docs.ipfs.tech/concepts/ipfs-implementations/" rel="noopener noreferrer">IPFS client</a> that verifies your data.</li>
+        {{ if or (eq .StatusCode 400) (eq .StatusCode 404) }}
+          <li>Inspect the <a href="https://cid.ipfs.tech/" rel="noopener noreferrer">CID</a> or <a href="https://explore.ipld.io/" rel="noopener noreferrer">DAG</a>.</li>
+        {{ end }}
+      </ul>
+    </section>
+  </main>
+</body>
+</html>

gateway/assets/header.html

@@ -0,0 +1,10 @@
+<header id="header">
+  <div class="ipfs-logo">&nbsp;</div>
+  <nav>
+    <a href="https://ipfs.tech" target="_blank" rel="noopener noreferrer">About<span class="dn-mobile"> IPFS</span></a>
+    <a href="https://ipfs.tech#install" target="_blank" rel="noopener noreferrer">Install<span class="dn-mobile"> IPFS</span></a>
+    {{ range .Menu }}
+      <a href="{{ .URL }}" target="_blank" rel="noopener noreferrer">{{ .Title }}</a>
+    {{ end }}
+  </nav>
+</header>