add debug API endpoint and signal listener

docs/content/api/blip.md

@@ -60,4 +60,14 @@ Returns the Blip version (same as [`--version`]({{< ref "/config/blip#--version"
 "v1.0.75"
 ```
 
-Response encoding is text (string).
+## GET /debug
+
+Toggles debug logging.
+
+*Response*
+
+```json
+{"debugging":true}
+```
+
+

docs/content/config/blip.md

@@ -55,6 +55,8 @@ In this case, Blip tries to auto-detect a local MySQL instance, which is useful
 
 Print debug to STDERR.
 
+You can also toggle debug logging by sending a request to the `/debug` [API endpoint]({{< ref "/api" >}}) or by sending the `SIGUSR1` signal to the Blip process.
+
 ### `--help`
 
 Print help and exit.

docs/content/config/logging.md

@@ -7,6 +7,7 @@ Start `blip` with the [`--log`]({{< ref "blip#--log" >}}) option to print info e
 
 <p class="note">
 <a href="blip#--debug">Debug</a> info is printed to <code>STDERR</code>.
+You can also toggle debug logging by sending a request to the `/debug` [API endpoint]({{< ref "/api" >}}) or by sending the `SIGUSR1` signal to the Blip process.
 </p>
 
 This is _pseudo-logging_ because there is no traditional log printing, only events that are printed by default.

server/api.go

@@ -50,6 +50,8 @@ func NewAPI(cfg blip.Config, ml *monitor.Loader) *API {
 	mux.HandleFunc("/status", api.status)
 	mux.HandleFunc("/status/monitors", api.statusMonitors)
 
+	mux.HandleFunc("/debug", api.debug)
+
 	api.httpServer = &http.Server{
 		Addr:    cfg.API.Bind,
 		Handler: mux,
@@ -123,7 +125,13 @@ func (api *API) registered(w http.ResponseWriter, r *http.Request) {
 
 func (api *API) version(w http.ResponseWriter, r *http.Request) {
 	blip.Debug("%v", r)
-	w.Write([]byte(blip.VERSION))
+	json.NewEncoder(w).Encode(blip.VERSION)
+}
+
+func (api *API) debug(w http.ResponseWriter, r *http.Request) {
+	blip.Debug("%v", r)
+	blip.Debugging = !blip.Debugging
+	json.NewEncoder(w).Encode(map[string]bool{"debugging": blip.Debugging})
 }
 
 // --------------------------------------------------------------------------

server/server.go

@@ -261,13 +261,23 @@ func (s *Server) Run(stopChan, doneChan chan struct{}) error {
 
 	// Run until caller closes stopChan or blip process catches a signal
 	status.Blip(status.SERVER, "running since %s", blip.FormatTime(time.Now()))
-	signalChan := make(chan os.Signal)
-	signal.Notify(signalChan, os.Interrupt, syscall.SIGTERM)
-	select {
-	case <-stopChan:
-		stopReason = "server stopped"
-	case <-signalChan:
-		stopReason = "caught signal"
+	signalChan := make(chan os.Signal, 1)
+	defer close(signalChan)
+	signal.Notify(signalChan, os.Interrupt, syscall.SIGTERM, syscall.SIGUSR1)
+	for {
+		select {
+		case <-stopChan:
+			stopReason = "server stopped"
+			return nil
+		case s := <-signalChan:
+			switch s {
+			case os.Interrupt, syscall.SIGTERM:
+				stopReason = "caught signal"
+				return nil
+			case syscall.SIGUSR1:
+				blip.Debugging = !blip.Debugging
+				fmt.Fprintf(os.Stderr, "SIGUSR1 has set blip.Debugging to %t\n", blip.Debugging)
+			}
+		}
 	}
-	return nil
 }