Use common.SignalHandlerLoop from weave, and document debug options.

README.md

@@ -210,3 +210,28 @@ Then, run the local build via
 ```
 ./scope launch
 ```
+
+## <a name="developing"></a>Debugging
+
+Scope has a collection of built in debugging tools to aid Scope delevopers.
+
+- To have the app or probe dump their goroutine stacks, run:
+```
+pkill -SIGQUIT scope-(app|probe)
+docker logs weavescope
+```
+
+- The probe is instrumented with various counters and timers. To have it dump
+  those values, run:
+```
+pkill -SIGUSR1 scope-probe
+docker logs weavescope
+```
+
+- The app and probe both include golang's pprof integration for gathering CPU
+  and memory profiles.  To use these with the probe, you must launch Scope with
+  the following arguments `scope launch --probe.http.listen :4041`.  You can
+  then collect profiles in the usual way:
+```
+go tool pprof http://localhost:(4040|4041)/debug/pprof/profile
+```

app/main.go

@@ -7,14 +7,12 @@ import (
 	"math/rand"
 	"net/http"
 	_ "net/http/pprof"
-	"os"
-	"os/signal"
 	"strconv"
 	"strings"
-	"syscall"
 	"time"
 
 	"github.com/gorilla/mux"
+	"github.com/weaveworks/weave/common"
 
 	"github.com/weaveworks/scope/xfer"
 )
@@ -71,11 +69,6 @@ func main() {
 		log.Printf("listening on %s", *listen)
 		log.Print(http.ListenAndServe(*listen, nil))
 	}()
-	log.Printf("%s", <-interrupt())
-}
 
-func interrupt() chan os.Signal {
-	c := make(chan os.Signal)
-	signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
-	return c
+	common.SignalHandlerLoop()
 }

prog/probe/main.go

@@ -9,13 +9,12 @@ import (
 	"net/http"
 	_ "net/http/pprof"
 	"os"
-	"os/signal"
 	"strconv"
 	"strings"
-	"syscall"
 	"time"
 
 	"github.com/armon/go-metrics"
+	"github.com/weaveworks/weave/common"
 
 	"github.com/weaveworks/scope/probe"
 	"github.com/weaveworks/scope/probe/controls"
@@ -176,11 +175,5 @@ func main() {
 	p.Start()
 	defer p.Stop()
 
-	log.Printf("%s", <-interrupt())
-}
-
-func interrupt() <-chan os.Signal {
-	c := make(chan os.Signal)
-	signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
-	return c
+	common.SignalHandlerLoop()
 }