diff --git a/config.yaml b/config.yaml
index 9ee036c8..122eab56 100644
--- a/config.yaml
+++ b/config.yaml
@@ -38,6 +38,10 @@ options:
     default: kvm
     type: string
     description: "Virtualization flavor. Supported: kvm, xen, uml, lxc. qemu"
+  multi-host:
+    default: "yes"
+    type: string
+    description: Whether to run nova-api and nova-network on the compute nodes.
   # needed if using flatmanager
   bridge-interface:
     default: br100
@@ -60,3 +64,13 @@ options:
     default: None
     type: string
     description: Comma separated list of key=value config flags to be set in nova.conf.
+  nagios_context:
+    default: "juju"
+    type: string
+    description: |
+      Used by the nrpe-external-master subordinate charm.
+      A string that will be prepended to instance name to set the host name
+      in nagios. So for instance the hostname would be something like:
+          juju-myservice-0
+      If you're running multiple environments with the same services in them
+      this allows you to differentiate between them.
diff --git a/hooks/nova-compute-common b/hooks/nova-compute-common
index 2faf19f1..2ce04546 100755
--- a/hooks/nova-compute-common
+++ b/hooks/nova-compute-common
@@ -7,6 +7,7 @@ CONF_DIR="/etc/nova"
 NOVA_CONF=$(config-get nova-config)
 API_CONF="/etc/nova/api-paste.ini"
 QUANTUM_CONF="/etc/quantum/quantum.conf"
+MULTI_HOST=$(config-get multi-host)
 
 if [ -f /etc/nova/nm.conf ]; then
     NET_MANAGER=$(cat /etc/nova/nm.conf)
@@ -28,7 +29,9 @@ case $NET_MANAGER in
     esac
     ;;
   "FlatManager"|"FlatDHCPManager")
-    SERVICES="$SERVICES nova-api nova-network"
+    if [[ "$MULTI_HOST" == "yes" ]] ; then
+      SERVICES="$SERVICES nova-api nova-network"
+    fi
     ;;
 esac
 
@@ -102,8 +105,10 @@ function configure_network_manager {
 
   case $net_manager in
     "FlatManager"|"FlatDHCPManager")
-      apt-get -y install nova-api nova-network
-      SERVICES="$SERVICES nova-api nova-network"
+      if [[ "$MULTI_HOST" == "yes" ]] ; then
+        apt-get -y install nova-api nova-network
+        SERVICES="$SERVICES nova-api nova-network"
+      fi
       ;;&
     "FlatManager")
       local bridge_ip=$(config-get bridge-ip)
@@ -177,3 +182,30 @@ cgroup_device_acl = [
 EOF
   service libvirt-bin reload
 }
+
+function give_me_numbers {
+  local name="$1"
+  local address=
+
+  case "$name" in
+    [A-Za-z]*)
+      address=$(getent hosts "$name" | awk '{print $1}')
+      case "$address" in
+        127.*)
+          address=$(dig +short "$name")
+          if [ -z "$address" ]; then
+            echo "$name"
+          fi
+          echo "$address"
+          ;;
+        *)
+          echo "$address"
+          ;;
+      esac
+      ;;
+    *)
+      # not a name, maybe it's an address?
+      echo "$name"
+      ;;
+  esac
+}
diff --git a/hooks/nova-compute-relations b/hooks/nova-compute-relations
index 976bc9b5..a1c449c9 100755
--- a/hooks/nova-compute-relations
+++ b/hooks/nova-compute-relations
@@ -9,6 +9,7 @@ else
 fi
 
 function install_hook {
+  [ -d exec.d ] && ( for f in exec.d/*/charm-pre-install; do [ -x $f ] && /bin/sh -c "$f";done )
   local virt_type=$(config-get virt-type)
   local compute_pkg=$(determine_compute_package "$virt_type")
   apt-get -y install python-software-properties || exit 1
@@ -20,6 +21,10 @@ function install_hook {
   configure_libvirt
 }
 
+function upgrade_hook {
+  [ -d exec.d ] && ( for f in exec.d/*/charm-pre-install; do [ -x $f ] && /bin/sh -c "$f";done )
+}
+
 function config_changed() {
 
   # Determine whether or not we should do an upgrade, based on whether or not
@@ -203,7 +208,7 @@ function ceph_changed {
   MONS=`relation-list`
   mon_hosts=""
   for mon in $MONS; do
-    mon_hosts="$mon_hosts `relation-get private-address $mon`:6789"
+    mon_hosts="$mon_hosts $(give_me_numbers $(relation-get private-address $mon)):6789"
   done
   cat > /etc/ceph/ceph.conf << EOF
 [global]
@@ -234,6 +239,7 @@ EOF
 
 case $ARG0 in
   "install") install_hook ;;
+  "upgrade-charm") upgrade_hook ;;
   "start"|"stop") exit 0 ;;
   "config-changed") config_changed ;;
   "amqp-relation-joined") amqp_joined ;;
diff --git a/metadata.yaml b/metadata.yaml
index ef7235b6..45421201 100644
--- a/metadata.yaml
+++ b/metadata.yaml
@@ -8,6 +8,9 @@ description: |
 provides:
   cloud-compute:
     interface: nova-compute
+  nrpe-external-master:
+    interface: nrpe-external-master
+    scope: container
 requires:
   shared-db:
     interface: mysql-shared