Merge pull request #17 from bboreham/11_http_interface

add 'weave status'

closes issue #11

README.md

@@ -349,12 +349,9 @@ The log verbosity can be increased by supplying the `-debug` flag when
 launching weave. Be warned, this will log information on a per-packet
 basis, so can produce a lot of output.
 
-One can ask a weave router to log a status report by sending it a USR1
-signal, e.g.
+One can ask a weave router to report its status with
 
-    kill -USR1 `docker inspect --format='{{ .State.Pid }}' weave`
-
-and then inspect the logs.
+    weave status
 
 ## Installation with Boot2Docker
 

consts.go

@@ -10,6 +10,7 @@ const (
 	EthernetOverhead   = 14
 	UDPOverhead        = 28 // 20 bytes for IPv4, 8 bytes for UDP
 	Port               = 6783
+	StatusPort         = Port + 1
 	DefaultPMTU        = 65535
 	MaxUDPPacketSize   = 65536
 	ChannelSize        = 16

weaver/main.go

@@ -6,9 +6,11 @@ import (
 	"crypto/sha256"
 	"flag"
 	"fmt"
+	"io"
 	"github.com/davecheney/profile"
 	"log"
 	"net"
+	"net/http"
 	"os"
 	"os/signal"
 	"runtime"
@@ -129,9 +131,22 @@ func main() {
 			}
 		}()
 	}
+	go handleHttp(router)
 	handleSignals(router)
 }
 
+func handleHttp(router *weave.Router) {
+	http.HandleFunc("/status", func(w http.ResponseWriter, r *http.Request) {
+		io.WriteString(w, router.Status())
+	})
+	address := fmt.Sprintf(":%d", weave.StatusPort)
+	err := http.ListenAndServe(address, nil)
+	if err != nil {
+		log.Fatal("Unable to create http listener: ", err)
+	}
+}
+
+
 func handleSignals(router *weave.Router) {
 	sigs := make(chan os.Signal, 1)
 	signal.Notify(sigs, syscall.SIGQUIT, syscall.SIGUSR1)

weaver/weave

@@ -7,10 +7,17 @@ usage() {
     echo "weave run    <ipaddr>/<subnet> <docker run args> ..."
     echo "weave expose <ipaddr>/<subnet>"
     echo "weave hide   <ipaddr>/<subnet>"
+    echo "weave status"
     echo "weave stop"
     exit 1
 }
 
+# utility function to check whether a command can be executed by the shell
+# see http://stackoverflow.com/questions/592620/how-to-check-if-a-program-exists-from-a-bash-script
+command_exists () {
+    command -v $1 >/dev/null 2>&1
+}
+
 [ `id -u` = 0 ] || {
     echo "weave must be run as 'root'"
     exit 1
@@ -71,6 +78,22 @@ case "$COMMAND" in
         echo $CONTAINER
         IFACE=eth0
         ;;
+    status)
+        DOCKERIP=$(docker inspect --format='{{ .NetworkSettings.IPAddress }}' weave)
+        if [ -z "$DOCKERIP" ] ; then
+            echo "The weave container is not running." >&2
+            exit 1
+        fi
+        if command_exists wget ; then
+            wget -O - -q $DOCKERIP:6784/status
+        elif command_exists curl ; then
+            curl $DOCKERIP:6784/status
+        else
+            echo "Cannot find wget or curl. Install one of them for 'weave status' to function." >&2
+            exit 1
+        fi
+        exit 0
+        ;;
     run)
         [ $# -gt 0 ] || usage
         IPADDR=$1
@@ -103,7 +126,7 @@ case "$COMMAND" in
     stop)
         docker kill weave > /dev/null
         docker rm weave > /dev/null
-        if command -v conntrack >/dev/null 2>&1
+        if command_exists conntrack
         then
             conntrack -D -p udp --dport 6783 >/dev/null 2>&1
         else
@@ -145,7 +168,7 @@ ip netns exec $NSPID ip link set $GUEST_IFNAME name $CONTAINER_IFNAME
 ip netns exec $NSPID ip addr add $IPADDR dev $CONTAINER_IFNAME
 ip netns exec $NSPID ip link set $CONTAINER_IFNAME up
 
-if command -v ethtool >/dev/null 2>&1
+if command_exists ethtool
 then
     ip netns exec $NSPID ethtool -K $IFACE tx off > /dev/null
 else