Make getting the docker run command easier (in fewer lines).

scope

@@ -25,18 +25,14 @@ IP_REGEXP="[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}"
 IP_ADDR_CMD="find /sys/class/net -type l | xargs -n1 basename | grep -vE 'docker|veth|lo' | \
     xargs -n1 ip addr show | grep inet | awk '{ print \$2 }' | grep -oE '$IP_REGEXP'"
 WEAVESCOPE_DOCKER_ARGS=${WEAVESCOPE_DOCKER_ARGS:-}
-DOCKER=docker
-if [ -n "${DRY_RUN+x}" ]; then
-    DOCKER="echo docker"
-fi
 
 [ $# -gt 0 ] || usage
 COMMAND=$1
 shift 1
 
 # Check that a container named $1 with image $2 is not running
 check_not_running() {
-    case $($DOCKER inspect --format='{{.State.Running}} {{.Config.Image}}' $1 2>/dev/null) in
+    case $(docker inspect --format='{{.State.Running}} {{.Config.Image}}' $1 2>/dev/null) in
         "true $2")
             echo "$1 is already running." >&2
             exit 1
@@ -62,26 +58,26 @@ check_not_running() {
     esac
 }
 
+launch_command() {
+  echo docker run --privileged -d --name=$SCOPE_CONTAINER_NAME --net=host --pid=host \
+            -v /var/run/docker.sock:/var/run/docker.sock \
+            $WEAVESCOPE_DOCKER_ARGS $SCOPE_IMAGE --probe.docker true "$@"
+}
+
 case "$COMMAND" in
     command)
-        DRY_RUN=true $0 launch
+        launch_command "$@"
         ;;
 
     launch)
         check_not_running $SCOPE_CONTAINER_NAME $SCOPE_IMAGE
-        DOCKER rm -f $SCOPE_CONTAINER_NAME >/dev/null 2>&1 || true
+        docker rm -f $SCOPE_CONTAINER_NAME >/dev/null 2>&1 || true
 
-
-        CONTAINER=$($DOCKER run --privileged -d --name=$SCOPE_CONTAINER_NAME --net=host --pid=host \
-            -v /var/run/docker.sock:/var/run/docker.sock \
-            $WEAVESCOPE_DOCKER_ARGS $SCOPE_IMAGE --probe.docker true "$@")
+        CONTAINER=$($(launch_command "$@"))
         echo $CONTAINER
-        if [ -n "${DRY_RUN+x}" ]; then
-            exit 0
-        fi
 
         if ! echo "$@" | grep -E "\-\-no\-app|\-\-service\-token" 1>/dev/null; then
-            IP_ADDRS=$($DOCKER run --rm --net=host --entrypoint /bin/sh $SCOPE_IMAGE -c "$IP_ADDR_CMD")
+            IP_ADDRS=$(docker run --rm --net=host --entrypoint /bin/sh $SCOPE_IMAGE -c "$IP_ADDR_CMD")
             echo "Weave Scope is reachable at the following URL(s):" >&2
             for ip in $IP_ADDRS; do
                 echo "  * http://$ip:4040/" >&2
@@ -91,7 +87,7 @@ case "$COMMAND" in
 
     stop)
         [ $# -eq 0 ] || usage
-        if ! $DOCKER stop $SCOPE_CONTAINER_NAME >/dev/null 2>&1 ; then
+        if ! docker stop $SCOPE_CONTAINER_NAME >/dev/null 2>&1 ; then
             echo "Weave Scope is not running." >&2
         fi
         ;;