Add back check for datapath supported

prog/weaveutil/datapath.go

@@ -31,6 +31,19 @@ func deleteDatapath(args []string) error {
 	return odp.DeleteDatapath(args[0])
 }
 
+// Checks whether a datapath can be created by actually creating and destroying it
+func checkDatapath(args []string) error {
+	if len(args) != 1 {
+		cmdUsage("check-datapath", "<datapath>")
+	}
+
+	if err := createDatapath(args); err != nil {
+		return err
+	}
+
+	return odp.DeleteDatapath(args[0])
+}
+
 func addDatapathInterface(args []string) error {
 	if len(args) != 2 {
 		cmdUsage("add-datapath-interface", "<datapath> <interface>")

prog/weaveutil/main.go

@@ -21,6 +21,7 @@ func init() {
 		"detect-bridge-type":       detectBridgeType,
 		"create-datapath":          createDatapath,
 		"delete-datapath":          deleteDatapath,
+		"check-datapath":           checkDatapath,
 		"add-datapath-interface":   addDatapathInterface,
 		"create-plugin-network":    createPluginNetwork,
 		"remove-plugin-network":    removePluginNetwork,

weave

@@ -442,7 +442,8 @@ validate_bridge_type() {
     detect_bridge_type || return 0
 
     if [ -n "$LAUNCHING_ROUTER" ] ; then
-        if [ "$BRIDGE_TYPE" = bridge -a -z "$WEAVE_NO_FASTDP" ] ; then
+        if [ "$BRIDGE_TYPE" = bridge -a -z "$WEAVE_NO_FASTDP" ] &&
+               util_op check-datapath 2>/dev/null ; then
             cat <<EOF >&2
 WEAVE_NO_FASTDP is not set, but there is already a bridge present of
 the wrong type for fast datapath.  Please do 'weave reset' to remove