Add LVM as a disk backend

Enables the use of Logical Volumes as disk backends.

It uses an existing volume group and has no support for creating a new one.
It will not override an existing logical volume and fail gracefully.

The lv is created, activated and then mounted as a loop device.
The boostraping process is then launched on the loop device.
Once the process is completed, the lv is unmounted and desactivated.

The created lv will be deleted should the boostraping process fail.

The lv must be activated before use.

A manifest has been included for testing purposes.

bootstrapvz/base/fs/__init__.py

@@ -25,13 +25,15 @@ def load_volume(data, bootloader):
     from bootstrapvz.common.fs.virtualharddisk import VirtualHardDisk
     from bootstrapvz.common.fs.virtualmachinedisk import VirtualMachineDisk
     from bootstrapvz.common.fs.folder import Folder
+    from bootstrapvz.common.fs.logicalvolume import LogicalVolume
     volume_backing = {'raw': LoopbackVolume,
                       's3':  LoopbackVolume,
                       'vdi': VirtualDiskImage,
                       'vhd': VirtualHardDisk,
                       'vmdk': VirtualMachineDisk,
                       'ebs': EBSVolume,
-                      'folder': Folder
+                      'folder': Folder,
+                      'lvm': LogicalVolume
                       }.get(data['backing'])
 
     # Instantiate the partition map

bootstrapvz/base/manifest-schema.yml

@@ -131,6 +131,12 @@ properties:
       ^\w+$: {}
     additionalProperties: false
   volume:
+    type: object
+    oneOf:
+        - $ref: '#/definitions/standardvolume'
+        - $ref: '#/definitions/logicalvolume'
+definitions:
+  standardvolume:
     type: object
     properties:
       backing: {type: string}
@@ -141,7 +147,20 @@ properties:
           - $ref: '#/definitions/partition_table'
     required: [partitions]
     additionalProperties: false
-definitions:
+  logicalvolume:
+    type: object
+    properties:
+      backing:
+        enum: [lvm]
+      volumegroup : {type: string}
+      logicalvolume: {type: string}
+      partitions:
+        type: object
+        oneOf:
+          - $ref: '#/definitions/no_partitions'
+          - $ref: '#/definitions/partition_table'
+    required: [partitions]
+    additionalProperties: false
   absolute_path:
     type: string
     pattern: ^/[^\0]+$

bootstrapvz/common/fs/logicalvolume.py

@@ -0,0 +1,38 @@
+from bootstrapvz.base.fs.volume import Volume
+from bootstrapvz.common.tools import log_check_call
+import os
+
+
+class LogicalVolume(Volume):
+
+    def __init__(self, partitionmap):
+        super(LogicalVolume, self).__init__(partitionmap)
+        self.vg = ''
+        self.lv = ''
+
+    def create(self, volumegroup, logicalvolume):
+        self.vg = volumegroup
+        self.lv = logicalvolume
+        image_path = os.path.join(os.sep, 'dev', self.vg, self.lv)
+        self.fsm.create(image_path=image_path)
+
+    def _before_create(self, e):
+        self.image_path = e.image_path
+        lv_size = str(self.size.bytes.get_qty_in('MiB'))
+        log_check_call(['lvcreate', '--size', '{mib}M'.format(mib=lv_size),
+                        '--name', self.lv, self.vg])
+
+    def _before_attach(self, e):
+        log_check_call(['lvchange', '--activate', 'y', self.image_path])
+        [self.loop_device_path] = log_check_call(['losetup', '--show', '--find', '--partscan', self.image_path])
+        self.device_path = self.loop_device_path
+
+    def _before_detach(self, e):
+        log_check_call(['losetup', '--detach', self.loop_device_path])
+        log_check_call(['lvchange', '--activate', 'n', self.image_path])
+        del self.loop_device_path
+        self.device_path = None
+
+    def delete(self):
+        log_check_call(['lvremove', '-f', self.image_path])
+        del self.image_path

bootstrapvz/common/tasks/logicalvolume.py

@@ -0,0 +1,37 @@
+import bootstrapvz.common.tasks.host as host
+import bootstrapvz.common.tasks.volume as volume
+from bootstrapvz.base import Task
+from bootstrapvz.common import phases
+
+
+class AddRequiredCommands(Task):
+    description = 'Adding commands required for creating and mounting logical volumes'
+    phase = phases.validation
+    successors = [host.CheckExternalCommands]
+
+    @classmethod
+    def run(cls, info):
+        from bootstrapvz.common.fs.logicalvolume import LogicalVolume
+        if type(info.volume) is LogicalVolume:
+            info.host_dependencies['lvcreate'] = 'lvm2'
+            info.host_dependencies['losetup'] = 'mount'
+
+
+class Create(Task):
+    description = 'Creating a Logical volume'
+    phase = phases.volume_creation
+    successors = [volume.Attach]
+
+    @classmethod
+    def run(cls, info):
+        info.volume.create(volumegroup=info.manifest.volume['volumegroup'],
+                           logicalvolume=info.manifest.volume['logicalvolume'])
+
+
+class Delete(Task):
+    description = 'Deleting a Logical volume'
+    phase = phases.cleaning
+
+    @classmethod
+    def run(cls, info):
+        info.volume.delete()

bootstrapvz/providers/kvm/README.rst

@@ -6,6 +6,7 @@ virtual images for Linux Kernel-based Virtual Machines. It supports the
 installation of `virtio kernel
 modules <http://www.linux-kvm.org/page/Virtio>`__ (paravirtualized
 drivers for IO operations).
+It also supports creating an image with LVM as a disk backend.
 
 Manifest settings
 -----------------
@@ -15,6 +16,9 @@ Provider
 
 -  ``virtio``: Specifies which virtio kernel modules to install.
    ``optional``
+-  ``logicalvolume``: Specifies the logical volume where the disk image will be built.
+   ``volumegroup``: Specifies the volume group where the logical volume will be stored.
+   These options should only be used if ``lvm`` was given as a disk backend.
 
 Example:
 
@@ -26,3 +30,7 @@ Example:
       virtio:
         - virtio_blk
         - virtio_net
+    volume:
+      backing: lvm
+      logicalvolume: lvtest
+      volumegroup: vgtest

bootstrapvz/providers/kvm/__init__.py

@@ -1,6 +1,6 @@
 from bootstrapvz.common import task_groups
 import tasks.packages
-from bootstrapvz.common.tasks import image, loopback, initd, ssh
+from bootstrapvz.common.tasks import image, loopback, initd, ssh, logicalvolume
 
 
 def validate_manifest(data, validator, error):
@@ -12,14 +12,20 @@ def resolve_tasks(taskset, manifest):
     taskset.update(task_groups.get_standard_groups(manifest))
 
     taskset.update([tasks.packages.DefaultPackages,
-                    loopback.AddRequiredCommands,
-                    loopback.Create,
                     initd.InstallInitScripts,
                     ssh.AddOpenSSHPackage,
                     ssh.ShredHostkeys,
                     ssh.AddSSHKeyGeneration,
-                    image.MoveImage,
                     ])
+    if manifest.volume.get('logicalvolume', []):
+        taskset.update([logicalvolume.AddRequiredCommands,
+                        logicalvolume.Create,
+                        ])
+    else:
+        taskset.update([loopback.AddRequiredCommands,
+                        loopback.Create,
+                        image.MoveImage,
+                        ])
 
     if manifest.provider.get('virtio', []):
         from tasks import virtio
@@ -28,3 +34,4 @@ def resolve_tasks(taskset, manifest):
 
 def resolve_rollback_tasks(taskset, manifest, completed, counter_task):
     taskset.update(task_groups.get_standard_rollback_tasks(completed))
+    counter_task(taskset, logicalvolume.Create, logicalvolume.Delete)

bootstrapvz/providers/kvm/manifest-schema.yml

@@ -32,7 +32,11 @@ properties:
     properties:
       backing:
         type: string
-        enum: [raw]
+        enum: 
+        - raw
+        - lvm
+      logicalvolume: {type: string}
+      volumegroup: {type: string}
       partitions:
         type: object
         properties:

manifests/examples/kvm/jessie-lvm.yml

@@ -0,0 +1,26 @@
+---
+name: debian-lvm-example
+provider:
+  name: kvm
+bootstrapper:
+  workspace: /target
+system:
+  release: jessie
+  architecture: amd64
+  bootloader: grub
+  charmap: UTF-8
+  locale: en_US
+  timezone: UTC
+volume:
+  backing: lvm
+  logicalvolume: lvtest
+  volumegroup: vgtest
+  partitions:
+    type: gpt
+    root:
+      filesystem: ext4
+      size: 1GB
+packages: {}
+plugins:
+  root_password:
+    password: test