Support cinder image conversion on an NFS share

New CinderImageConversionNfsShare and CinderImageConversionNfsOptions
parameters add support for mounting an external NFS share for cinder
to use when converting glance images to or from another format (e.g.
qcow2 versus raw).

This feature is useful in preventing the node's root disk from filling
up in situations where the available disk space is too small, which
can happen in deployments that utilize very large glance images.

Change-Id: If7b3640191d84e5cf30cbbcb1cc94aa0f068d11c

deployment/cinder/cinder-common-container-puppet.yaml

@@ -61,6 +61,16 @@ parameters:
       be managed by pacemaker. If these criteria are not met then the cluster
       name must be left blank.
     type: string
+  CinderImageConversionNfsShare:
+    default: ''
+    description: When set, the NFS share to be used for Cinder's image conversion
+                 directory.
+    type: string
+  CinderImageConversionNfsOptions:
+    default: '_netdev,bg,intr,context=system_u:object_r:container_file_t:s0'
+    description: NFS mount options when using an NFS share for Cinder's image
+                 conversion directory.
+    type: string
   EnableInternalTLS:
     type: boolean
     default: false
@@ -112,11 +122,24 @@ conditions:
       - {get_param: EnableInternalTLS}
       - {get_param: EnableEtcdInternalTLS}
 
+  cinder_nfs_conversion_dir_enabled:
+    not:
+      equals:
+        - {get_param: CinderImageConversionNfsShare}
+        - ''
+
 resources:
   ContainersCommon:
     type: ../containers-common.yaml
 
 outputs:
+  cinder_image_conversion_nfs_dir:
+    description: The directory where cinder does its image conversion when the
+                 directory is backed by an NFS share.
+    value: &cinder_image_conversion_nfs_dir
+      # Avoid SELinux conflicts by choosing a location outside /var/lib/cinder
+      /var/lib/cinder_image_conversion
+
   cinder_common_host_prep_tasks:
     description: Common host prep tasks for cinder-volume and cinder-backup services
     value: &cinder_common_host_prep_tasks
@@ -210,7 +233,26 @@ outputs:
     value:
       list_concat:
         - *cinder_common_host_prep_tasks
-        -
+        - - name: Support using an NFS share for cinder image conversion
+            vars:
+              image_conversion_nfs_enabled: {if: [cinder_nfs_conversion_dir_enabled, true, false]}
+            when:
+              - image_conversion_nfs_enabled|bool
+            block:
+              - name: Create cinder image conversion directory
+                file:
+                  path: *cinder_image_conversion_nfs_dir
+                  state: directory
+              - name: Mount cinder's image conversion NFS share
+                vars:
+                  image_conversion_nfs_share: {get_param: CinderImageConversionNfsShare}
+                  image_conversion_nfs_options: {get_param: CinderImageConversionNfsOptions}
+                mount:
+                  path: *cinder_image_conversion_nfs_dir
+                  state: mounted
+                  fstype: nfs4
+                  src: "{{ image_conversion_nfs_share }}"
+                  opts: "{{ image_conversion_nfs_options }}"
           - name: cinder_enable_iscsi_backend fact
             set_fact:
               cinder_enable_iscsi_backend: {get_param: CinderEnableIscsiBackend}
@@ -283,6 +325,14 @@ outputs:
                   enabled: yes
                   daemon_reload: yes
 
+  cinder_volume_config_settings:
+    description: Config settings for the cinder-volume container (HA or non-HA)
+    value:
+      if:
+        - cinder_nfs_conversion_dir_enabled
+        - cinder::image_conversion_dir: *cinder_image_conversion_nfs_dir
+        - {}
+
   cinder_volume_volumes:
     description: Volumes for the cinder-volume container (HA or non-HA)
     value:
@@ -309,6 +359,14 @@ outputs:
           - {get_param: MultipathdEnable}
           - - /etc/multipath:/etc/multipath:z
             - /etc/multipath.conf:/etc/multipath.conf:ro
+        - if:
+          - cinder_nfs_conversion_dir_enabled
+          - - str_replace:
+                # Use slave propagation so if the mount is delayed on the host
+                # it will also be updated within the cinder-volume container.
+                template: DIR:DIR:slave
+                params:
+                  DIR: *cinder_image_conversion_nfs_dir
 
   cinder_volume_environment:
     description: Docker environment for the cinder-volume container (HA or non-HA)

deployment/cinder/cinder-volume-container-puppet.yaml

@@ -237,8 +237,9 @@ outputs:
       config_settings:
         map_merge:
           - get_attr: [CinderBase, role_data, config_settings]
+          - get_attr: [CinderCommon, cinder_volume_config_settings]
           - tripleo::profile::base::lvm::enable_udev: false
-          - tripleo::profile::base::cinder::volume::cinder_enable_iscsi_backend: {get_param: CinderEnableIscsiBackend}
+            tripleo::profile::base::cinder::volume::cinder_enable_iscsi_backend: {get_param: CinderEnableIscsiBackend}
             tripleo::profile::base::cinder::volume::cinder_enable_nfs_backend: {get_param: CinderEnableNfsBackend}
             tripleo::profile::base::cinder::volume::cinder_enable_rbd_backend: {get_param: CinderEnableRbdBackend}
             tripleo::profile::base::cinder::volume::cinder_volume_cluster: {get_param: CinderVolumeCluster}

releasenotes/notes/cinder-nfs-conversion-dir-ba9b8dce515808ce.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    The following parameters add support for mounting Cinder's image
+    conversion directory on an external NFS share.
+
+    * CinderImageConversionNfsShare
+    * CinderImageConversionNfsOptions