xenapi: xe network-attach for OVS bridge creation

For Neutron we need an additional OVS bridge to be present. The xe
network-create command did not create the bridge immediately. A
workaround was applied to attach a network interface to that network,
forcing xapi to create the underlying OVS bridge. It turned out, that
the xe network-attach command could be used instead, so the workaround
is removed and replaced with the proper solution by this patch.

Fixes bug 1197305

Change-Id: I10cc763531b71238f0bc12a12de985f8f35d7e27
diff --git a/tools/xen/functions b/tools/xen/functions
index 4e37554..fd14075 100644
--- a/tools/xen/functions
+++ b/tools/xen/functions
@@ -250,3 +250,21 @@
     done
     unset IFS
 }
+
+function have_multiple_hosts() {
+    xe host-list --minimal | grep -q ","
+}
+
+function attach_network() {
+    local bridge_or_net_name
+
+    bridge_or_net_name="$1"
+
+    local net
+    local host
+
+    net=$(_network_uuid "$bridge_or_net_name")
+    host=$(xe host-list --minimal)
+
+    xe network-attach uuid=$net host-uuid=$host
+}
diff --git a/tools/xen/install_os_domU.sh b/tools/xen/install_os_domU.sh
index 21aa729..6eb3013 100755
--- a/tools/xen/install_os_domU.sh
+++ b/tools/xen/install_os_domU.sh
@@ -50,6 +50,15 @@
 
 cd $THIS_DIR
 
+# Die if multiple hosts listed
+if have_multiple_hosts; then
+    cat >&2 << EOF
+ERROR: multiple hosts found. This might mean that the XenServer is a member
+of a pool - Exiting.
+EOF
+    exit 1
+fi
+
 # Install plugins
 
 ## Nova plugins
@@ -256,7 +265,7 @@
 # is created by XenServer). This is required for Neutron. Also pass that as a
 # kernel parameter for DomU
 if is_service_enabled neutron; then
-    add_interface "$GUEST_NAME" "$XEN_INT_BRIDGE_OR_NET_NAME" $XEN_INT_DEV_NR
+    attach_network "$XEN_INT_BRIDGE_OR_NET_NAME"
 
     XEN_INTEGRATION_BRIDGE=$(bridge_for "$XEN_INT_BRIDGE_OR_NET_NAME")
     append_kernel_cmdline \
diff --git a/tools/xen/xenrc b/tools/xen/xenrc
index 97c0930..03b30ac 100644
--- a/tools/xen/xenrc
+++ b/tools/xen/xenrc
@@ -35,7 +35,6 @@
 MGT_DEV_NR=0
 VM_DEV_NR=1
 PUB_DEV_NR=2
-XEN_INT_DEV_NR=3
 
 # Host Interface, i.e. the interface on the nova vm you want to expose the
 # services on. Usually the device connected to the management network or the