From f8cc5d1ad8e1b03754242539c93cb22b4fce0a0d Mon Sep 17 00:00:00 2001
From: bin <bin@hyper.sh>
Date: Fri, 8 Apr 2022 16:32:29 +0800
Subject: [PATCH] kata-monitor: add some links when generating pages for
 browsers

Add some links to rendered webpages for better user experience,
let users can jump to pages only by clicking links in browsers.

Fixes: #4061

Signed-off-by: bin <bin@hyper.sh>
---
 src/runtime/cmd/kata-monitor/main.go    | 35 +++++++++++++++++++++++--
 src/runtime/pkg/kata-monitor/metrics.go | 15 +++++++++++
 src/runtime/pkg/kata-monitor/monitor.go | 35 +++++++++++++++++++++++++
 src/runtime/pkg/kata-monitor/pprof.go   |  2 ++
 4 files changed, 85 insertions(+), 2 deletions(-)

diff --git a/src/runtime/cmd/kata-monitor/main.go b/src/runtime/cmd/kata-monitor/main.go
index 356316dcf2..86b5693d9b 100644
--- a/src/runtime/cmd/kata-monitor/main.go
+++ b/src/runtime/cmd/kata-monitor/main.go
@@ -175,6 +175,15 @@ func main() {
 }
 
 func indexPage(w http.ResponseWriter, r *http.Request) {
+	htmlResponse := kataMonitor.IfReturnHTMLResponse(w, r)
+	if htmlResponse {
+		indexPageHTML(w, r)
+	} else {
+		indexPageText(w, r)
+	}
+}
+
+func indexPageText(w http.ResponseWriter, r *http.Request) {
 	w.Write([]byte("Available HTTP endpoints:\n"))
 
 	spacing := 0
@@ -184,13 +193,35 @@ func indexPage(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 	spacing = spacing + 3
+	formatter := fmt.Sprintf("%%-%ds: %%s\n", spacing)
 
-	formattedString := fmt.Sprintf("%%-%ds: %%s\n", spacing)
 	for _, endpoint := range endpoints {
-		w.Write([]byte(fmt.Sprintf(formattedString, endpoint.path, endpoint.desc)))
+		w.Write([]byte(fmt.Sprintf(formatter, endpoint.path, endpoint.desc)))
 	}
 }
 
+func indexPageHTML(w http.ResponseWriter, r *http.Request) {
+
+	w.Write([]byte("<h1>Available HTTP endpoints:</h1>\n"))
+
+	var formattedString string
+	needLinkPaths := []string{"/metrics", "/sandboxes"}
+
+	w.Write([]byte("<ul>"))
+	for _, endpoint := range endpoints {
+		formattedString = fmt.Sprintf("<b>%s</b>: %s\n", endpoint.path, endpoint.desc)
+		for _, linkPath := range needLinkPaths {
+			if linkPath == endpoint.path {
+				formattedString = fmt.Sprintf("<b><a href='%s'>%s</a></b>: %s\n", endpoint.path, endpoint.path, endpoint.desc)
+				break
+			}
+		}
+		formattedString = fmt.Sprintf("<li>%s</li>", formattedString)
+		w.Write([]byte(formattedString))
+	}
+	w.Write([]byte("</ul>"))
+}
+
 // initLog setup logger
 func initLog() {
 	kataMonitorLog := logrus.WithFields(logrus.Fields{
diff --git a/src/runtime/pkg/kata-monitor/metrics.go b/src/runtime/pkg/kata-monitor/metrics.go
index 7249906cea..e5d9477670 100644
--- a/src/runtime/pkg/kata-monitor/metrics.go
+++ b/src/runtime/pkg/kata-monitor/metrics.go
@@ -78,6 +78,21 @@ func (km *KataMonitor) ProcessMetricsRequest(w http.ResponseWriter, r *http.Requ
 		scrapeDurationsHistogram.Observe(float64(time.Since(start).Nanoseconds() / int64(time.Millisecond)))
 	}()
 
+	// this is likely the same as `kata-runtime metrics <SANDBOX>`.
+	sandboxID, err := getSandboxIDFromReq(r)
+	if err == nil && sandboxID != "" {
+		metrics, err := GetSandboxMetrics(sandboxID)
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte(err.Error()))
+			return
+		}
+		w.Write([]byte(metrics))
+		return
+	}
+
+	// if no sandbox provided, will get all sandbox's metrics.
+
 	// prepare writer for writing response.
 	contentType := expfmt.Negotiate(r.Header)
 
diff --git a/src/runtime/pkg/kata-monitor/monitor.go b/src/runtime/pkg/kata-monitor/monitor.go
index ed3ea5c089..1e60a50b7b 100644
--- a/src/runtime/pkg/kata-monitor/monitor.go
+++ b/src/runtime/pkg/kata-monitor/monitor.go
@@ -27,6 +27,7 @@ const (
 	RuntimeCRIO                 = "cri-o"
 	fsMonitorRetryDelaySeconds  = 60
 	podCacheRefreshDelaySeconds = 5
+	contentTypeHtml             = "text/html"
 )
 
 // SetLogger sets the logger for katamonitor package.
@@ -194,7 +195,41 @@ func (km *KataMonitor) GetAgentURL(w http.ResponseWriter, r *http.Request) {
 // ListSandboxes list all sandboxes running in Kata
 func (km *KataMonitor) ListSandboxes(w http.ResponseWriter, r *http.Request) {
 	sandboxes := km.sandboxCache.getSandboxList()
+	htmlResponse := IfReturnHTMLResponse(w, r)
+	if htmlResponse {
+		listSandboxesHtml(sandboxes, w)
+	} else {
+		listSandboxesText(sandboxes, w)
+	}
+}
+
+func listSandboxesText(sandboxes []string, w http.ResponseWriter) {
 	for _, s := range sandboxes {
 		w.Write([]byte(fmt.Sprintf("%s\n", s)))
 	}
 }
+func listSandboxesHtml(sandboxes []string, w http.ResponseWriter) {
+	w.Write([]byte("<h1>Sandbox list</h1>\n"))
+	w.Write([]byte("<ul>\n"))
+	for _, s := range sandboxes {
+		w.Write([]byte(fmt.Sprintf("<li>%s: <a href='/debug/pprof/?sandbox=%s'>pprof</a>, <a href='/metrics?sandbox=%s'>metrics</a>, <a href='/agent-url?sandbox=%s'>agent-url</a></li>\n", s, s, s, s)))
+	}
+	w.Write([]byte("</ul>\n"))
+}
+
+// IfReturnHTMLResponse returns true if request accepts html response
+// NOTE: IfReturnHTMLResponse will also set response header to `text/html`
+func IfReturnHTMLResponse(w http.ResponseWriter, r *http.Request) bool {
+	accepts := r.Header["Accept"]
+	for _, accept := range accepts {
+		fields := strings.Split(accept, ",")
+		for _, field := range fields {
+			if field == contentTypeHtml {
+				w.Header().Set("Content-Type", contentTypeHtml)
+				return true
+			}
+		}
+	}
+
+	return false
+}
diff --git a/src/runtime/pkg/kata-monitor/pprof.go b/src/runtime/pkg/kata-monitor/pprof.go
index 5dac2da03c..a2ff76bc30 100644
--- a/src/runtime/pkg/kata-monitor/pprof.go
+++ b/src/runtime/pkg/kata-monitor/pprof.go
@@ -55,8 +55,10 @@ func (km *KataMonitor) proxyRequest(w http.ResponseWriter, r *http.Request) {
 	}
 
 	uri := fmt.Sprintf("http://shim%s", r.URL.String())
+	monitorLog.Debugf("proxyRequest to: %s, uri: %s", socketAddress, uri)
 	resp, err := client.Get(uri)
 	if err != nil {
+		serveError(w, http.StatusInternalServerError, fmt.Sprintf("failed to request %s through %s", uri, socketAddress))
 		return
 	}