[pve-devel] [PATCH-SERIES guest-common/docs v3] add pre/post/failed snapshot hooks

[Stefan Hanreich <s.hanreich@proxmox.com>]

This patch series introduces the pre/post/failed-snapshot hooks that run before/
after a snapshot is taken, or after failing to take a snapshot.

I used the new example script from pve-docs as template for my test hookscripts.

What I tested:
* Normal snapshotting, without VM state, without hookscript
  * snapshot works, no hooks executed
* Normal snapshotting, with VM state, without hookscript
  * snapshot works, no hooks executed
* Normal snapshotting, without VM state, with hookscript
  * snapshot works, pre/post hooks work
* Normal snapshotting, with VM state, with hookscript
  * snapshot works, pre/post hooks work
* Taking snapshot with existing name, with hookscript
  * fails, no hookscripts get executed
* Failed at wrong storage config, with hookscript
  * pre/failed get executed, lock gets released
* Failed at taking RAM Snapshot (simulated with monkey-patched die), with hookscript
  * pre/failed get executed, lock gets released
* pre/post hookscript that detaches/attaches unsnapshottable disk (without --skiplock)
  * snapshotting fails, attach/detach fails, pre/failed get executed, lock released
* pre/post hookscript that detaches/attaches unsnapshottable disk (with --skiplock)
  * snapshotting works, attach/detach works, pre/post get executed
  * restoring works, detached disk is detached after restoring
* pre-snapshot hookscript exits with code > 0
  * pre/failed-snapshot get executed, snapshot fails, lock gets released
* post-snapshot hookscript exits with code > 0
  * pre/post/failed-snapshot get executed, snapshot fails, lock gets released
* Taking snapshot of template
  * fails, no hookscripts get executed
* execute commands in VM in pre/post via qm guest exec
  * snapshot succeeds, commands get executed, pre/post executed

Changes from v2 (thanks fabian!):
* added guards, so cfs_update() only gets called when necessary
* added PVE_SNAPSHOT_PHASE envvar to failed-snapshot as indicator
  when the failure occured

Changes from v1:
* added failed-snapshot hook that runs after a failed snapshot
  * this enables users to revert any changes made in pre-snapshot hooks
  in case of errors
* running cfs_update() after every hookscript invocation
* adjusted the call sites of exec_hookscript()
  * particularly interesting for pre-snapshot since some checks now run
  before the hook runs
* VM/CT config is now locked during hookscript execution

Thanks to Fiona and Fabian for their valuable input/help!

pve-guest-common:

Stefan Hanreich (1):
  examples: add pre/post/failed-snapshot hooks to example hookscript

 examples/guest-example-hookscript.pl | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)


pve-docs:

Stefan Hanreich (1):
  partial fix #2530: snapshots: add pre/post/failed-snapshot hooks

 src/PVE/AbstractConfig.pm | 76 +++++++++++++++++++++++++++++++++++----
 1 file changed, 70 insertions(+), 6 deletions(-)

-- 
2.30.2