Exporter Landing page

Add a configurable exporer landing page generator. Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu> Co-authored-by: Ben Kochie <superq@gmail.com>
prometheus · Mar 2, 2023 · 00162f9 · 00162f9
1 parent 3d42407
commit 00162f9
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diff --git a/web/landing_page.css b/web/landing_page.css
@@ -0,0 +1,13 @@
+body {
+  font-family: -apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,Liberation Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji;
+  margin: 0;
+}
+nav {
+  background-color: {{.HeaderColor}};
+  color: #fff;
+  font-size: 2rem;
+  padding: 1rem;
+}
+.main {
+  padding: 1rem;
+}
diff --git a/web/landing_page.go b/web/landing_page.go
@@ -0,0 +1,82 @@
+// Copyright 2023 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.
+
+//go:build !genassets
+// +build !genassets
+
+//go:generate go run -tags genassets gen_assets.go
+
+package web
+
+import (
+	"bytes"
+	_ "embed"
+	"net/http"
+	"text/template"
+)
+
+// Config represents the configuration of the web listener.
+type LandingConfig struct {
+	HeaderColor string         // Used for the landing page header.
+	CSS         string         // CSS style tag for the landing page.
+	Name        string         // The name of the exporter, generally suffixed by _exporter.
+	Description string         // A short description about the exporter.
+	Links       []LandingLinks // Links displayed on the landing page.
+	Version     string         // The version displayed.
+}
+
+type LandingLinks struct {
+	Address     string // The URL the link points to.
+	Text        string // The text of the link.
+	Description string // A descriptive textfor the link.
+}
+
+type LandingPageHandler struct {
+	landingPage []byte
+}
+
+var (
+	//go:embed landing_page.html
+	landingPagehtmlContent string
+	//go:embed landing_page.css
+	landingPagecssContent string
+)
+
+func NewLandingPage(c LandingConfig) (*LandingPageHandler, error) {
+	var buf bytes.Buffer
+	if c.CSS == "" {
+		if c.HeaderColor == "" {
+			// Default to Prometheus orange.
+			c.HeaderColor = "#e6522c"
+		}
+		cssTemplate := template.Must(template.New("landing css").Parse(landingPagecssContent))
+		if err := cssTemplate.Execute(&buf, c); err != nil {
+			return nil, err
+		}
+		c.CSS = buf.String()
+	}
+	t := template.Must(template.New("landing page").Parse(landingPagehtmlContent))
+
+	buf.Reset()
+	if err := t.Execute(&buf, c); err != nil {
+		return nil, err
+	}
+
+	return &LandingPageHandler{
+		landingPage: buf.Bytes(),
+	}, nil
+}
+
+func (h *LandingPageHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	w.Write(h.landingPage)
+}
diff --git a/web/landing_page.html b/web/landing_page.html
@@ -0,0 +1,21 @@
+<!doctype html>
+<html>
+  <head>
+    <meta charset="utf-8">
+    <title>{{.Name}}</title>
+    <style>{{.CSS}}</style>
+  </head>
+  <body>
+    <nav>{{.Name}}</nav>
+    <div class="main">
+      {{if .Description}}<h3>{{.Description}}</h3>{{end}}
+      {{if .Version}}<div>Version: {{.Version}}</div>{{end}}
+      <div><ul>
+        {{ range .Links }}
+        <li><a href="{{ .Address }}">{{.Text}}</a>{{if .Description}}: {{.Description}}{{end}}</li>
+        {{ end }}
+        </ul>
+      </div>
+    </div>
+  </body>
+</html>