Allow storage backend to be configurable

Add configurables so that one need not have Ceph be the storage
backend for Cinder, Cinder-backup, Glance and Nova.

Let Ceph be the default storage backend for Cinder, Cinder backup,
Glance, and Nova. Allow the default setting to be overriden when the
global config, ENABLE_CEPH_{CINDER,C_BAK,GLANCE,NOVA} is set to
False in the local.conf/localrc file.

Closes Bug: #1521278

Change-Id: I3afe7c57d5d56f15fe533ad5b1dbe36ccd369e6b

README.md

@@ -25,8 +25,19 @@ This plugin also gets used to configure Ceph as the storage backend for the upst
 
     ```enable_plugin devstack-plugin-ceph git://git.openstack.org/openstack/devstack-plugin-ceph```
 
+  _Note: Ceph can be disabled as the storage backend for a service with the
+  following setting in the ```localrc``` file,_
+
+    ```
+    ENABLE_CEPH_$SERVICE=False
+    ```
+
+  _where $SERVICE can be CINDER, C_BAK, GLANCE, or NOVA corresponding to
+  Cinder, Cinder Backup, Glance, and Nova services respectively._
+
 * Then run ```stack.sh``` and wait for the _magic_ to happen :)
 
+
 # TODOs
 
 * Configuring Rados Gateway with Keystone for Swift

devstack/lib/ceph

@@ -90,6 +90,24 @@ ATTACH_ENCRYPTED_VOLUME_AVAILABLE=False
 # Functions
 # ------------
 
+# is_ceph_enabled_for_service() - checks whether the OpenStack service
+# specified as an argument is enabled with Ceph as its storage backend.
+function is_ceph_enabled_for_service {
+    local config config_name enabled service
+    enabled=1
+    service=$1
+    # Construct the global variable ENABLE_CEPH_.* corresponding to a
+    # $service.
+    config_name=ENABLE_CEPH_$(echo $service | \
+                                    tr '[:lower:]' '[:upper:]' | tr '-' '_')
+    config=$(eval echo "\$$config_name")
+
+    if (is_service_enabled $service) && [[ $config == 'True' ]]; then
+        enabled=0
+    fi
+    return $enabled
+}
+
 function get_ceph_version {
 local ceph_version_str
 ceph_version_str=$(sudo ceph daemon mon.$(hostname) version\
@@ -119,7 +137,8 @@ sudo rm -f secret.xml
 
 # undefine_virsh_secret() - Undefine Cinder key secret from libvirt
 function undefine_virsh_secret {
-if is_service_enabled cinder || is_service_enabled nova; then
+if is_ceph_enabled_for_service cinder || \
+is_ceph_enabled_for_service nova; then
     local virsh_uuid
     virsh_uuid=$(sudo virsh secret-list | awk '/^ ?[0-9a-z]/ { print $1 }')
     sudo virsh secret-undefine ${virsh_uuid} >/dev/null 2>&1
@@ -145,25 +164,25 @@ fi
 # runs that a clean run would need to clean up
 function cleanup_ceph_remote {
 # do a proper cleanup from here to avoid leftover on the remote Ceph cluster
-if is_service_enabled glance; then
+if is_ceph_enabled_for_service glance; then
     sudo ceph osd pool delete $GLANCE_CEPH_POOL $GLANCE_CEPH_POOL \
     --yes-i-really-really-mean-it > /dev/null 2>&1
 
     sudo ceph auth del client.$GLANCE_CEPH_USER > /dev/null 2>&1
 fi
-if is_service_enabled cinder; then
+if is_ceph_enabled_for_service cinder; then
     sudo ceph osd pool delete $CINDER_CEPH_POOL $CINDER_CEPH_POOL \
     --yes-i-really-really-mean-it > /dev/null 2>&1
 
     sudo ceph auth del client.$CINDER_CEPH_USER > /dev/null 2>&1
 fi
-if is_service_enabled c-bak; then
+if is_ceph_enabled_for_service c-bak; then
     sudo ceph osd pool delete $CINDER_BAK_CEPH_POOL $CINDER_BAK_CEPH_POOL \
     --yes-i-really-really-mean-it > /dev/null 2>&1
 
     sudo ceph auth del client.$CINDER_BAK_CEPH_USER > /dev/null 2>&1
 fi
-if is_service_enabled nova; then
+if is_ceph_enabled_for_service nova; then
     iniset $NOVA_CONF libvirt rbd_secret_uuid ""
     sudo ceph osd pool delete $NOVA_CEPH_POOL $NOVA_CEPH_POOL \
     --yes-i-really-really-mean-it > /dev/null 2>&1
@@ -431,7 +450,7 @@ iniset $NOVA_CONF libvirt images_type rbd
 iniset $NOVA_CONF libvirt images_rbd_pool ${NOVA_CEPH_POOL}
 iniset $NOVA_CONF libvirt images_rbd_ceph_conf ${CEPH_CONF_FILE}
 
-if ! is_service_enabled cinder; then
+if ! is_ceph_enabled_for_service cinder; then
     sudo ceph -c ${CEPH_CONF_FILE} \
     auth get-or-create client.${CINDER_CEPH_USER} \
     mon "allow r" \

devstack/override-defaults

@@ -1,4 +1,11 @@
 # Plug-in overrides
 
-CINDER_DRIVER=ceph
-CINDER_ENABLED_BACKENDS=ceph
+ENABLE_CEPH_CINDER=$(trueorfalse True ENABLE_CEPH_CINDER)
+ENABLE_CEPH_C_BAK=$(trueorfalse True ENABLE_CEPH_C_BAK)
+ENABLE_CEPH_GLANCE=$(trueorfalse True ENABLE_CEPH_GLANCE)
+ENABLE_CEPH_NOVA=$(trueorfalse True ENABLE_CEPH_NOVA)
+
+if [[ $ENABLE_CEPH_CINDER == "True" ]]; then
+    CINDER_DRIVER=ceph
+    CINDER_ENABLED_BACKENDS=ceph
+fi

devstack/plugin.sh

@@ -21,19 +21,20 @@ elif [[ "$1" == "stack" && "$2" == "pre-install" ]]; then
         install_ceph_remote
     fi
 elif [[ "$1" == "stack" && "$2" == "post-config" ]]; then
-    if is_service_enabled glance; then
+    if is_ceph_enabled_for_service glance; then
         echo_summary "Configuring Glance for Ceph"
         configure_ceph_glance
     fi
-    if is_service_enabled nova; then
+    if is_ceph_enabled_for_service nova; then
         echo_summary "Configuring Nova for Ceph"
         configure_ceph_nova
     fi
-    if is_service_enabled cinder; then
+    if is_ceph_enabled_for_service cinder; then
         echo_summary "Configuring Cinder for Ceph"
         configure_ceph_cinder
     fi
-    if is_service_enabled cinder || is_service_enabled nova; then
+    if is_ceph_enabled_for_service cinder || \
+    is_ceph_enabled_for_service nova; then
         # NOTE (leseb): the part below is a requirement
         # to attach Ceph block devices
         echo_summary "Configuring libvirt secret"
@@ -41,15 +42,15 @@ elif [[ "$1" == "stack" && "$2" == "post-config" ]]; then
     fi
 
     if [ "$REMOTE_CEPH" = "False" ]; then
-        if is_service_enabled glance; then
+        if is_ceph_enabled_for_service glance; then
             echo_summary "Configuring Glance for Ceph"
             configure_ceph_embedded_glance
         fi
-        if is_service_enabled nova; then
+        if is_ceph_enabled_for_service nova; then
             echo_summary "Configuring Nova for Ceph"
             configure_ceph_embedded_nova
         fi
-        if is_service_enabled cinder; then
+        if is_ceph_enabled_for_service cinder; then
             echo_summary "Configuring Cinder for Ceph"
             configure_ceph_embedded_cinder
         fi