prober: add a status page handler

This change adds an HTTP handler with a table showing a list of all
probes, their status, and a button that allows triggering a specific
probe.

Updates tailscale/corp#20583

Signed-off-by: Anton Tolchanov <anton@tailscale.com>
pull/13010/head
Anton Tolchanov 3 months ago committed by Anton Tolchanov
parent 153a476957
commit 9b08399d9e

@ -0,0 +1,124 @@
// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package prober
import (
"embed"
"fmt"
"html/template"
"net/http"
"strings"
"time"
"tailscale.com/tsweb"
"tailscale.com/util/mak"
)
//go:embed status.html
var statusFiles embed.FS
var statusTpl = template.Must(template.ParseFS(statusFiles, "status.html"))
type statusHandlerOpt func(*statusHandlerParams)
type statusHandlerParams struct {
title string
pageLinks map[string]string
probeLinks map[string]string
}
// WithTitle sets the title of the status page.
func WithTitle(title string) statusHandlerOpt {
return func(opts *statusHandlerParams) {
opts.title = title
}
}
// WithPageLink adds a top-level link to the status page.
func WithPageLink(text, url string) statusHandlerOpt {
return func(opts *statusHandlerParams) {
mak.Set(&opts.pageLinks, text, url)
}
}
// WithProbeLink adds a link to each probe on the status page.
// The textTpl and urlTpl are Go templates that will be rendered
// with the respective ProbeInfo struct as the data.
func WithProbeLink(textTpl, urlTpl string) statusHandlerOpt {
return func(opts *statusHandlerParams) {
mak.Set(&opts.probeLinks, textTpl, urlTpl)
}
}
// StatusHandler is a handler for the probe overview HTTP endpoint.
// It shows a list of probes and their current status.
func (p *Prober) StatusHandler(opts ...statusHandlerOpt) tsweb.ReturnHandlerFunc {
params := &statusHandlerParams{
title: "Prober Status",
}
for _, opt := range opts {
opt(params)
}
return func(w http.ResponseWriter, r *http.Request) error {
type probeStatus struct {
ProbeInfo
TimeSinceLast time.Duration
Links map[string]template.URL
}
vars := struct {
Title string
Links map[string]template.URL
TotalProbes int64
UnhealthyProbes int64
Probes map[string]probeStatus
}{
Title: params.title,
}
for text, url := range params.pageLinks {
mak.Set(&vars.Links, text, template.URL(url))
}
for name, info := range p.ProbeInfo() {
vars.TotalProbes++
if !info.Result {
vars.UnhealthyProbes++
}
s := probeStatus{ProbeInfo: info}
if !info.End.IsZero() {
s.TimeSinceLast = time.Since(info.End)
}
for textTpl, urlTpl := range params.probeLinks {
text, err := renderTemplate(textTpl, info)
if err != nil {
return tsweb.Error(500, err.Error(), err)
}
url, err := renderTemplate(urlTpl, info)
if err != nil {
return tsweb.Error(500, err.Error(), err)
}
mak.Set(&s.Links, text, template.URL(url))
}
mak.Set(&vars.Probes, name, s)
}
if err := statusTpl.ExecuteTemplate(w, "status", vars); err != nil {
return tsweb.HTTPError{Code: 500, Err: err, Msg: "error rendering status page"}
}
return nil
}
}
// renderTemplate renders the given Go template with the provided data
// and returns the result as a string.
func renderTemplate(tpl string, data any) (string, error) {
t, err := template.New("").Parse(tpl)
if err != nil {
return "", fmt.Errorf("error parsing template %q: %w", tpl, err)
}
var buf strings.Builder
if err := t.ExecuteTemplate(&buf, "", data); err != nil {
return "", fmt.Errorf("error rendering template %q with data %v: %w", tpl, data, err)
}
return buf.String(), nil
}

@ -0,0 +1,132 @@
{{define "status"}}
<html>
<head><title>{{.Title}}</title></head>
<style>
body {
/* max-width: 60rem; */
margin-left: auto;
margin-right: auto;
padding: 3rem 1rem 8rem;
line-height: 1.4;
font-size: 1rem;
font-weight: 400;
font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, Segoe UI, Roboto, Helvetica Neue, Arial, Noto Sans, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol, Noto Color Emoji;
text-rendering: optimizeLegibility;
}
.small {
font-size: 0.7rem;
}
h1 {
font-weight: 500;
letter-spacing: -.025em;
}
a { color: rgb(74 125 221); }
a:hover { color: rgb(73 100 149); }
ul {
list-style: none;
margin: 0;
padding: 0;
}
ul>li::before {
position: absolute;
top: .625rem;
left: .125rem;
height: .375rem;
width: .375rem;
border-radius: 9999px;
background-color: currentColor;
opacity: .4;
content: "";
}
ul>li {
position: relative;
padding-left: 1.25rem;
}
th, td {
padding: 5px;
text-align: left;
background: #eeeeee;
}
.error {
color: red;
}
</style>
<body>
<h1>{{.Title}}</h1>
<ul>
<li>Prober Status:
{{if .UnhealthyProbes }}
<span class="error">{{.UnhealthyProbes}}</span>
out of {{.TotalProbes}} probes failed or never ran.
{{else}}
All {{.TotalProbes}} probes are healthy
{{end}}
</li>
{{ range $text, $url := .Links }}
<li><a href="{{$url}}">{{$text}}</a></li>
{{end}}
</ul>
<h1>Probes:</h1>
<table class="sortable">
<thead><tr>
<th>Name</th>
<th>Class & Labels</th>
<th>Interval</th>
<th>Result</th>
<th>Success</th>
<th>Latency</th>
<th>Error</th>
</tr></thead>
<tbody>
{{range $name, $probeInfo := .Probes}}
<tr>
<td>
{{$name}}
{{range $text, $url := $probeInfo.Links}}
<br/>
<button onclick="location.href='{{$url}}';" type="button">
{{$text}}
</button>
{{end}}
</td>
<td>{{$probeInfo.Class}}<br/>
<div class="small">
{{range $label, $value := $probeInfo.Labels}}
{{$label}}={{$value}}<br/>
{{end}}
</div>
</td>
<td>{{$probeInfo.Interval}}</td>
<td data-sort="{{$probeInfo.TimeSinceLast.Milliseconds}}">
{{if $probeInfo.TimeSinceLast}}
{{$probeInfo.TimeSinceLast.String}}<br/>
<span class="small">{{$probeInfo.End}}</span>
{{else}}
Never
{{end}}
</td>
<td>
{{if $probeInfo.Result}}
{{$probeInfo.Result}}
{{else}}
<span class="error">{{$probeInfo.Result}}</span>
{{end}}<br/>
<div class="small">Recent: {{$probeInfo.RecentResults}}</div>
<div class="small">Mean: {{$probeInfo.RecentSuccessRatio}}</div>
</td>
<td data-sort="{{$probeInfo.Latency.Milliseconds}}">
{{$probeInfo.Latency.String}}
<div class="small">Recent: {{$probeInfo.RecentLatencies}}</div>
<div class="small">Median: {{$probeInfo.RecentMedianLatency}}</div>
</td>
<td class="small">{{$probeInfo.Error}}</td>
</tr>
{{end}}
</tbody>
</table>
<link href="https://cdn.jsdelivr.net/gh/tofsjonas/sortable@latest/sortable-base.min.css" rel="stylesheet" />
<script src="https://cdn.jsdelivr.net/gh/tofsjonas/sortable@latest/sortable.min.js"></script>
</body>
</html>
{{end}}
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