MNAIO: Enable using a data disk for file-backed VM's

In order to make use of a data disk, we enable the 'file'
implementation of default_vm_disk_mode to use a data disk
much like the 'lvm' implementation.

To simplify changing from the default_vm_disk_mode of lvm
to file and back again, the setup-host playbook will remove
any previous implementation and replace it. This is useful
when doing testing for these different modes because it
does not require cleaning up by hand.

This patch also fixes the implementation of the virt
storage pool. Currently the tasks only execute if
'virt_data_volume.pools is not defined', but it is always
defined so the tasks never execute. We now ensure that
for both backing stores the 'default' storage pool is
defined, started and set to auto start (as three tasks
because the virt_pool module sucks really bad and can only
do one thing at a time).

The pool implementation for the 'file' backed VM's uses
the largest data disk it can find and creates the /data
mount for it. To cater for a different configuration, we
ensure that all references to the disk files use the path
that is configured in the pool ,rather than assuming the
path.

Change-Id: If7e7e37df4d7c0ebe9d003e5b5b97811d41eff22

multi-node-aio/README.rst

@@ -263,9 +263,9 @@ backing store) for the VM's, then set the following option before executing
 
 If you wish to save the current file-based images in order to implement a
 thin-provisioned set of VM's which can be saved and re-used, then use the
-``save-vms.yml`` playbook. This will stop the VM's and save the files to
+``save-vms.yml`` playbook. This will stop the VM's and rename the files to
-``/var/lib/libvirt/images/*-base.img``. Re-executing the ``deploy-vms.yml``
+``*-base.img``. Re-executing the ``deploy-vms.yml`` playbook afterwards will
-playbook afterwards will rebuild the VMs from those images.
+rebuild the VMs from those images.
 
 .. code-block:: bash
 

multi-node-aio/playbooks/deploy-vms.yml

@@ -31,6 +31,11 @@
       tags:
         - always
 
+    - name: Get info about the virt storage pools
+      virt_pool:
+        command: info
+      register: _virt_pools
+
     - name: Stop running VMs
       virt:
         name: "{{ hostvars[item]['server_hostname'] }}"
@@ -53,7 +58,7 @@
 
     - name: Delete VM Disk Image
       file:
-        path: "/var/lib/libvirt/images/{{ hostvars[item]['server_hostname'] }}.img"
+        path: "{{ _virt_pools.pools.default.path | default('/data') }}/{{ hostvars[item]['server_hostname'] }}.img"
         state: absent
       when:
         - hostvars[item]['server_vm'] | default(false) | bool
@@ -84,7 +89,7 @@
       block:
         - name: Find existing base image files
           find:
-            paths: /var/lib/libvirt/images
+            paths: "{{ _virt_pools.pools.default.path | default('/data') }}"
             patterns: '*-base.img'
           register: _base_images
 
@@ -99,9 +104,9 @@
             qemu-img create
             -f qcow2
             {% if vm_use_snapshot | bool %}
-            -b /var/lib/libvirt/images/{{ hostvars[item]['server_hostname'] }}-base.img
+            -b {{ _virt_pools.pools.default.path | default('/data') }}/{{ hostvars[item]['server_hostname'] }}-base.img
             {% endif %}
-            /var/lib/libvirt/images/{{ hostvars[item]['server_hostname'] }}.img
+            {{ _virt_pools.pools.default.path | default('/data') }}/{{ hostvars[item]['server_hostname'] }}.img
             {{ default_vm_storage }}m
           when:
             - hostvars[item]['server_vm'] | default(false) | bool

multi-node-aio/playbooks/kvm/kvm-vm.xml.j2

@@ -41,7 +41,7 @@
 {% elif default_vm_disk_mode == "file" %}
     <disk type='file' device='disk'>
       <driver name='qemu' type='qcow2' cache='none' io='native'/>
-      <source file='/var/lib/libvirt/images/{{ hostvars[item]["server_hostname"] }}.img'/>
+      <source file='{{ _virt_pools.pools.default.path | default('/data') }}/{{ hostvars[item]["server_hostname"] }}.img'/>
 {% endif %}
       <target dev='vda' bus='virtio'/>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x09' function='0x0'/>

multi-node-aio/playbooks/save-vms.yml

@@ -31,6 +31,11 @@
       tags:
         - always
 
+    - name: Get info about the virt storage pools
+      virt_pool:
+        command: info
+      register: _virt_pools
+
     - name: Stop running VMs
       command: "virsh destroy {{ hostvars[item]['server_hostname'] }}"
       failed_when: false
@@ -41,8 +46,8 @@
     - name: Save VM Disk Image
       command: >-
         mv
-        /var/lib/libvirt/images/{{ hostvars[item]['server_hostname'] }}.img
+        {{ _virt_pools.pools.default.path | default('/data') }}/{{ hostvars[item]['server_hostname'] }}.img
-        /var/lib/libvirt/images/{{ hostvars[item]['server_hostname'] }}-base.img
+        {{ _virt_pools.pools.default.path | default('/data') }}/{{ hostvars[item]['server_hostname'] }}-base.img
       when:
         - hostvars[item]['server_vm'] | default(false) | bool
       with_items: "{{ groups['pxe_servers'] }}"

multi-node-aio/playbooks/setup-host.yml

@@ -242,77 +242,153 @@
       with_dict: "{{ mnaio_host_networks }}"
       when: "item.value.iface not in vm_networks.list_nets"
 
-    - name: Locate data volume
+    - name: Locate the largest writable data disk if mnaio_data_disk is not set
-      command: "vgdisplay vg01"
-      failed_when: false
-      when:
-        - default_vm_disk_mode == "lvm"
-      register: data_volume
-
-    - name: Setup the data volume (LVM)
-      when:
-        - default_vm_disk_mode == "lvm"
-        - data_volume.rc != 0
-      block:
-        - name: Locate data disk
       shell: >
         lsblk -brndo NAME,TYPE,FSTYPE,RO,SIZE | awk '/d[b-z]+ disk +0/{ if ($4>m){m=$4; d=$1}}; END{print d}'
       register: lsblk
+      changed_when: false
       when:
         - mnaio_data_disk is undefined
 
-        - name: Create data disk label
+    - name: Get info about existing virt storage pools
-          command: "parted --script /dev/{{ mnaio_data_disk | default(lsblk.stdout) }} mklabel gpt"
+      virt_pool:
+        command: info
+      register: _virt_pools
 
-        - name: Create data disk partition
+    - name: If an existing virt pool does not match default_vm_disk_mode, remove it
-          command: "parted --align optimal --script /dev/{{ mnaio_data_disk | default(lsblk.stdout) }} mkpart data1 ext4 0% 100%"
+      when:
+        - _virt_pools.pools.default is defined
+        - (default_vm_disk_mode == "file" and _virt_pools.pools.default.format is defined) or
+          (default_vm_disk_mode == "lvm" and _virt_pools.pools.default.format is not defined)
+      block:
+        - name: Dismount the mount point if default_vm_disk_mode is 'lvm'
+          mount:
+            path: /data
+            state: unmounted
+          when:
+            - default_vm_disk_mode == "lvm"
 
-        - name: Create data volume group
+        - name: Stop the pool
+          virt_pool:
+            command: destroy
+            name: default
+
+        - name: Delete the pool, destroying its contents
+          virt_pool:
+            command: delete
+            name: default
+
+        - name: Undefine the pool
+          virt_pool:
+            command: undefine
+            name: default
+
+        - name: Remove the mount point if default_vm_disk_mode is 'lvm'
+          mount:
+            path: /data
+            state: absent
+          when:
+            - default_vm_disk_mode == "lvm"
+
+        - name: Reload systemd to remove generated unit files for mount
+          systemd:
+            daemon_reload: yes
+          when:
+            - default_vm_disk_mode == "lvm"
+
+        - name: Remove the volume group if default_vm_disk_mode is 'file'
+          lvg:
+            vg: vg01
+            state: absent
+          register: _remove_vg
+          when:
+            - default_vm_disk_mode == "file"
+
+        - name: Remove the existing disk partition
+          parted:
+            device: "/dev/{{ mnaio_data_disk | default(lsblk.stdout) }}"
+            number: 1
+            state: absent
+
+    - name: Setup the data disk partition
+      parted:
+        device: "/dev/{{ mnaio_data_disk | default(lsblk.stdout) }}"
+        label: gpt
+        number: 1
+        name: data1
+        state: present
+      register: _add_partition
+
+    - name: Prepare the data disk for 'lvm' default_vm_disk_mode
+      when:
+        - default_vm_disk_mode == "lvm"
+      block:
+        - name: Create the volume group
           lvg:
             vg: vg01
             pvs: "/dev/{{ mnaio_data_disk | default(lsblk.stdout) }}1"
 
-    - name: Locate virt data volume
+        - name: Define the default virt storage pool
           virt_pool:
-        name: "vg01"
+            name: default
-        command: info
+            state: present
-      failed_when: false
+            xml: |
+              <pool type='logical'>
+                <name>default</name>
+                <source>
+                  <name>vg01</name>
+                  <format type='lvm2'/>
+                </source>
+                <target>
+                  <path>/dev/vg01</path>
+                </target>
+              </pool>
+
+    - name: Prepare the data disk for 'file' default_vm_disk_mode
       when:
-        - default_vm_disk_mode == "lvm"
+        - default_vm_disk_mode == "file"
-      register: virt_data_volume
-
-    - name: Create /etc/libvirt/storage directory
-      file:
-        path: "/etc/libvirt/storage/"
-        state: "directory"
-
-    - name: Create virt data volume
       block:
-        - name: Create virt pool
+        - name: Prepare the data disk file system
-          virt_pool:
+          filesystem:
-            command: create
+            fstype: ext4
-            name: vg01
+            dev: "/dev/{{ mnaio_data_disk | default(lsblk.stdout) }}1"
-
+            force: yes
-        - name: Get virt pool xml
-          virt_pool:
-            command: get_xml
-            name: vg01
-          register: virt_pool_xml
-
-        - name: Write data volume xml
-          copy:
-            content: "{{ virt_pool_xml.get_xml }}"
-            dest: "/etc/libvirt/storage/vg01.xml"
-
-        - name: Define virt data volume
-          virt_pool:
-            command: define
-            name: vg01
-            xml: "/etc/libvirt/storage/vg01.xml"
-            autostart: true
           when:
-        - default_vm_disk_mode == "lvm"
+            - _add_partition is changed
-        - virt_data_volume.pools is not defined
+
+        - name: Mount the data disk
+          mount:
+            src: "/dev/{{ mnaio_data_disk | default(lsblk.stdout) }}1"
+            path: /data
+            state: mounted
+            fstype: ext4
+
+        - name: Define the default virt storage pool
+          virt_pool:
+            name: default
+            state: present
+            xml: |
+              <pool type='dir'>
+                <name>default</name>
+                <target>
+                  <path>/data</path>
+                  <permissions>
+                    <mode>0755</mode>
+                    <owner>0</owner>
+                    <group>0</group>
+                  </permissions>
+                </target>
+              </pool>
+
+    - name: Set default virt storage pool to active
+      virt_pool:
+        name: default
+        state: active
+
+    - name: Set default virt storage pool to autostart
+      virt_pool:
+        name: default
+        autostart: yes
 
     - name: Load virtio kernel modules
       shell: |