122 lines
2.6 KiB
Go
122 lines
2.6 KiB
Go
package main
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import (
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_ "embed"
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"fmt"
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"html/template"
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"net/http"
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_ "net/http/pprof"
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"os"
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"strings"
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"time"
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"github.com/coder/websocket"
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"github.com/coder/websocket/wsjson"
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"k8s.io/klog"
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)
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var (
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//go:embed index.html
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templateIndexText string
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templateIndex = template.Must(template.New("index").Parse(templateIndexText))
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)
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func formatVolts(v float32) string {
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return fmt.Sprintf("%.4f V", v)
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}
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// formatMbar formats a millibar value using scientific notation and returns a
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// HTML fragment (for superscript support).
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func formatMbar(v float32) template.HTML {
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exp := 0
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for v < 1 {
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v *= 10
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exp -= 1
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}
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for v >= 10 {
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v /= 10
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exp += 1
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}
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res := fmt.Sprintf("%.3f", v)
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res += fmt.Sprintf(" x 10<sup>%d</sup>", exp)
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res += " mbar"
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return template.HTML(res)
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}
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// httpIndex is the / view.
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func (d *daemon) httpIndex(w http.ResponseWriter, r *http.Request) {
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if r.URL.Path != "/" {
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http.NotFound(w, r)
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return
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}
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volts, mbar := d.pirani()
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loadB, err := os.ReadFile("/proc/loadavg")
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load := "unknown"
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if err == nil {
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parts := strings.Fields(string(loadB))
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load = strings.Join(parts[:3], " ")
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}
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hostname, err := os.Hostname()
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if err != nil {
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hostname = "unknown"
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}
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templateIndex.Execute(w, map[string]any{
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"volts": formatVolts(volts),
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"mbar": formatMbar(mbar),
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"hostname": hostname,
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"load": load,
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})
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}
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// httpStream is the websocket clientwards data hose, returning a 10Hz update
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// stream of pressure/voltage.
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func (d *daemon) httpStream(w http.ResponseWriter, r *http.Request) {
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c, err := websocket.Accept(w, r, nil)
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if err != nil {
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return
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}
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defer c.CloseNow()
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t := time.NewTicker(time.Second / 10)
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defer t.Stop()
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ctx := c.CloseRead(r.Context())
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for {
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select {
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case <-ctx.Done():
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c.Close(websocket.StatusNormalClosure, "")
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return
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case <-t.C:
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// TODO(q3k): don't poll, get notified when new ADC readout is available.
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volts, mbar := d.pirani()
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v := struct {
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Volts string
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Mbar string
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MbarFloat float32
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}{
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Volts: formatVolts(volts),
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Mbar: string(formatMbar(mbar)),
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MbarFloat: mbar,
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}
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if err := wsjson.Write(ctx, c, v); err != nil {
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klog.Errorf("Websocket write failed: %v", err)
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return
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}
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}
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}
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}
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// httpMetrics serves minimalistic Prometheus-compatible metrics.
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func (d *daemon) httpMetrics(w http.ResponseWriter, r *http.Request) {
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// TODO(q3k): also serve Go stuff using the actual Prometheus metrics client
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// library.
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_, mbar := d.pirani()
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fmt.Fprintf(w, "# HELP sem_pressure_mbar Pressure in the SEM chamber, in millibar\n")
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fmt.Fprintf(w, "# TYPE sem_pressure_mbar gauge\n")
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fmt.Fprintf(w, "sem_pressure_mbar %f\n", mbar)
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}
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