[pve-devel] [RFC qemu/storage/qemu-server/container/manager 00/23] backup provider API
Fiona Ebner
f.ebner at proxmox.com
Tue Jul 23 11:56:01 CEST 2024
======
A backup provider needs to implement a storage plugin as well as a
backup provider plugin. The storage plugin is for integration in
Proxmox VE's front-end, so users can manage the backups via
UI/API/CLI. The backup provider plugin is for interfacing with the
backup provider's backend to integrate backup and restore with that
backend into Proxmox VE.
This is an initial draft of an API and required changes to the backup
stack in Proxmox VE to make it work. Depending on feedback from other
developers and interested parties, it can still substantially change.
======
The backup provider API is split into two parts, both of which again
need different implementations for VM and LXC guests:
1. Backup API
There hook callbacks for the start/end/abort phases of guest backups
as well as for start/end/abort phases of a whole backup job.
The backup_get_mechanism() method is used to decide on the backup
mechanism. Currently only 'nbd' for VMs and 'directory' for containers
are possible. It also let's the plugin decide whether to use a bitmap
for incremental VM backup or not.
Next, there are methods for backing up guest and firewall
configuration as well as for the backup mechanisms:
- a container filesystem using a provided directory. The directory
contains an unchanging copy of the container's file system.
- a VM disk using a provided NBD export. The export is an unchanging
copy of the VM's disk. Either the full image, or in case a bitmap is
used, the dirty parts of the image since the last time the bitmap
was used for a successful backup. Reading outside of the dirty parts
will result in an error. After backing up each part of the disk, it
should be discarded in the export to avoid unnecessary space usage
on the Proxmox VE side (there is an associated fleecing image).
Finally, some helpers like getting the provider name or volume ID for
the backup target, as well as for handling the backup log.
2. Restore API
The restore_get_mechanism() method is used to decide on the restore
mechanism. Currently, only 'qemu-img' for VMs and 'directory' and
'tar' for containers are possible.
Next, methods for extracting the guest and firewall configuration and
the implementations of the restore mechanism. It is enough to
implement one restore mechanism per guest type of course:
- for VMs, with the 'qemu-img' mechanism, the backup provider gives a
path to the disk image that will be restore. The path should be
something qemu-img can deal with, e.g. can also be an NBD URI.
- for containers, with the 'directory' mechanism, the backup provider
gives the path to a directory with the full filesystem structure of
the container.
- for containers, with the 'tar' mechanism, the backup provider gives
the path to a (potentially compressed) tar archive with the full
filesystem structure of the container.
For VMs, there also is a restore_qemu_get_device_info() helper
required, to get the disks included in the backup and their sizes.
See the PVE::BackupProvider::Plugin module for the full API
documentation.
======
This series adapts the backup stack in Proxmox VE to allow using the
above API. For QEMU, backup access setup and teardown QMP commands are
implemented to be able to provide access to a consistent disk state to
the backup provider.
The series also provides an example implementation for a backup
provider as a proof-of-concept, exposing the different features.
======
Open questions:
Should the backup provider plugin system also follow the same API
age+version schema with a Custom/ directory for external plugins
derived from the base plugin?
Should there also be hook callbacks (i.e. start/end/abort) for
restore?
Should the bitmap action be passed directly to the backup provider?
I.e. have 'not-used', 'not-used-removed', 'new', 'used', 'invalid',
instead of only 'none', 'new' and 'reuse'. It makes API slightly more
complicated. Is there any situation where backup provider could care
if bitmap is new, because it was the first or bitmap is new because
previous was invalid? Both cases require the backup provider to do a
full backup.
======
The patches marked as PATCH rather than RFC can make sense
independently, with QEMU patches 02 and 03 having been sent already
before (touching same code, so included here):
https://lore.proxmox.com/pve-devel/20240625133551.210636-1-f.ebner@proxmox.com/#r
======
Feedback is very welcome, especially from people wishing to implement
such a backup provider plugin! Please tell me what issues you see with
the proposed API, what would and wouldn't work from your perspective?
======
Dependencies: pve-manager, pve-container and qemu-server all depend on
new libpve-storage-perl. pve-manager also build-depends on the new
libpve-storage-perl for its tests. To keep things clean, pve-manager
should also depend on new pve-container and qemu-server.
In qemu-server, there is no version guard added yet, as that depends
on the QEMU version the feature will land in.
======
qemu:
Fiona Ebner (9):
block/reqlist: allow adding overlapping requests
PVE backup: fixup error handling for fleecing
PVE backup: factor out setting up snapshot access for fleecing
PVE backup: save device name in device info structure
PVE backup: include device name in error when setting up snapshot
access fails
PVE backup: add target ID in backup state
PVE backup: get device info: allow caller to specify filter for which
devices use fleecing
PVE backup: implement backup access setup and teardown API for
external providers
PVE backup: implement bitmap support for external backup access
block/copy-before-write.c | 3 +-
block/reqlist.c | 2 -
pve-backup.c | 619 +++++++++++++++++++++++++++++++++-----
pve-backup.h | 16 +
qapi/block-core.json | 58 ++++
system/runstate.c | 6 +
6 files changed, 633 insertions(+), 71 deletions(-)
create mode 100644 pve-backup.h
storage:
Fiona Ebner (3):
plugin: introduce new_backup_provider() method
extract backup config: delegate to backup provider if there is one
add backup provider example
src/PVE/BackupProvider/DirectoryExample.pm | 533 ++++++++++++++++++
src/PVE/BackupProvider/Makefile | 6 +
src/PVE/BackupProvider/Plugin.pm | 343 +++++++++++
src/PVE/Makefile | 1 +
src/PVE/Storage.pm | 22 +-
.../Custom/BackupProviderDirExamplePlugin.pm | 289 ++++++++++
src/PVE/Storage/Custom/Makefile | 5 +
src/PVE/Storage/Makefile | 1 +
src/PVE/Storage/Plugin.pm | 15 +
9 files changed, 1213 insertions(+), 2 deletions(-)
create mode 100644 src/PVE/BackupProvider/DirectoryExample.pm
create mode 100644 src/PVE/BackupProvider/Makefile
create mode 100644 src/PVE/BackupProvider/Plugin.pm
create mode 100644 src/PVE/Storage/Custom/BackupProviderDirExamplePlugin.pm
create mode 100644 src/PVE/Storage/Custom/Makefile
qemu-server:
Fiona Ebner (7):
move nbd_stop helper to QMPHelpers module
backup: move cleanup of fleecing images to cleanup method
backup: cleanup: check if VM is running before issuing QMP commands
backup: allow adding fleecing images also for EFI and TPM
backup: implement backup for external providers
restore: die early when there is no size for a device
backup: implement restore for external providers
PVE/API2/Qemu.pm | 33 +++++-
PVE/CLI/qm.pm | 3 +-
PVE/QemuServer.pm | 139 +++++++++++++++++++++-
PVE/QemuServer/QMPHelpers.pm | 6 +
PVE/VZDump/QemuServer.pm | 218 +++++++++++++++++++++++++++++++----
5 files changed, 365 insertions(+), 34 deletions(-)
container:
Fiona Ebner (2):
backup: implement backup for external providers
backup: implement restore for external providers
src/PVE/LXC/Create.pm | 143 ++++++++++++++++++++++++++++++++++++++++++
src/PVE/VZDump/LXC.pm | 20 +++++-
2 files changed, 162 insertions(+), 1 deletion(-)
manager:
Fiona Ebner (2):
ui: backup: also check for backup subtype to classify archive
backup: implement backup for external providers
PVE/VZDump.pm | 43 +++++++++++++++++++++++++-----
test/vzdump_new_test.pl | 3 +++
www/manager6/Utils.js | 10 ++++---
www/manager6/grid/BackupView.js | 4 +--
www/manager6/storage/BackupView.js | 4 +--
5 files changed, 50 insertions(+), 14 deletions(-)
Summary over all repositories:
27 files changed, 2423 insertions(+), 122 deletions(-)
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