Make iowait example get correct hostname when launced remotely

examples/plugins/iowait/Makefile

@@ -5,7 +5,12 @@ IMAGE=weavescope-iowait-plugin
 UPTODATE=.$(EXE).uptodate
 
 run: $(UPTODATE)
-	docker run --rm -it --privileged -v /var/run/scope/plugins:/var/run/scope/plugins --name $(IMAGE) $(IMAGE) -hostname=$(shell hostname)
+	# --net=host gives us the remote hostname, in case we're being launched against a non-local docker host.
+	# We could also pass in the `-hostname=foo` flag, but that doesn't work against a remote docker host.
+	docker run --rm -it \
+		--net=host \
+		-v /var/run/scope/plugins:/var/run/scope/plugins \
+		--name $(IMAGE) $(IMAGE)
 
 $(UPTODATE): $(EXE) Dockerfile
 	docker build -t $(IMAGE) .

examples/plugins/iowait/main.go

@@ -22,7 +22,7 @@ func main() {
 	)
 	flag.Parse()
 
-	log.Println("Starting...")
+	log.Printf("Starting on %s...\n", *hostID)
 
 	// Check we can get the iowait for the system
 	_, err := iowait()
@@ -80,7 +80,9 @@ func (p *Plugin) Report(w http.ResponseWriter, r *http.Request) {
 				 %q: {
 					 "metrics": {
 						 "iowait": {
-							 "samples": [ {"date": %q, "value": %f} ]
+							 "samples": [ {"date": %q, "value": %f} ],
+							 "min": 0,
+							 "max": 100
 						 }
 					 }
 				 }