[pmg-devel] [PATCH pmg-api v2] backup: restore: keep directories in /etc/pmg for inotify

[pmg-devel] [PATCH pmg-api v2] backup: restore: keep directories in /etc/pmg for inotify

[Stoiko Ivanov]

By wiping the subdirectories in /etc/pmg/, we lose the inotify
watchers upon restore (/etc/pmg itself and thus most configs are
currently handled by the keep_root flag to rmtree)
This can lead to inconsistencies after restoring for parts relying on
config in a subdirectory (e.g. /etc/pmg/pbs/pbs.conf).

This patch uses File::Find (included in perl-modules-$perlver) to keep
all directories an unlink everything else.
This was chosen for future robustness over keeping an explicit list of
directories to keep, in case a new directory gets added.

quickly tested with a fifo, chardev, and socket in the directory.

an alternative approach would be to simply reload pmgdaemon/pmgproxy
upon config-restore, but that feels more likely to miss some
(potentially future) service, expecting inotify to work.

Reported-by: Fiona Ebner <f.ebner@proxmox.com>
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
v1->v2:
* do not track an explicit list of directories, but simply keep all
  (as suggested by Fiona)
* use File::Find, since it's present if perl-modules is installed

I did not put this in a helper by itself in pve-common, because it seems
short/direct enough to not warrant it.

 src/PMG/Backup.pm | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/PMG/Backup.pm b/src/PMG/Backup.pm
index a46167c..e6994c9 100644
--- a/src/PMG/Backup.pm
+++ b/src/PMG/Backup.pm
@@ -4,6 +4,7 @@ use strict;
 use warnings;
 use Data::Dumper;
 use File::Basename;
+use File::Find;
 use File::Path;
 use POSIX qw(strftime);
 
@@ -306,8 +307,13 @@ sub pmg_restore {
 	    unlink "$dirname/config/etc/pmg/cluster.conf"; # never restore cluster config
 	    rmtree "$dirname/config/etc/pmg/master";
 
-	    # remove current config, but keep directory for INotify
-	    rmtree("/etc/pmg", { keep_root => 1 });
+	    # remove current config, but keep directories for INotify
+	    File::Find::find({ wanted => sub {
+		if ( ! -d $File::Find::name) {
+		    unlink($File::Find::name) || die "removing $File::Find::name failed: $!\n";
+		}
+	    }}, '/etc/pmg');
+
 	    # copy files
 	    system("cp -a $dirname/config/etc/pmg/* /etc/pmg/") == 0 ||
 		die "unable to restore system configuration: ERROR";
-- 
2.30.2

Re: [pmg-devel] [PATCH pmg-api v2] backup: restore: keep directories in /etc/pmg for inotify

[Fiona Ebner]

Am 30.11.22 um 18:07 schrieb Stoiko Ivanov:
> By wiping the subdirectories in /etc/pmg/, we lose the inotify
> watchers upon restore (/etc/pmg itself and thus most configs are
> currently handled by the keep_root flag to rmtree)
> This can lead to inconsistencies after restoring for parts relying on
> config in a subdirectory (e.g. /etc/pmg/pbs/pbs.conf).
> 
> This patch uses File::Find (included in perl-modules-$perlver) to keep
> all directories an unlink everything else.
> This was chosen for future robustness over keeping an explicit list of
> directories to keep, in case a new directory gets added.
> 
> quickly tested with a fifo, chardev, and socket in the directory.
> 
> an alternative approach would be to simply reload pmgdaemon/pmgproxy
> upon config-restore, but that feels more likely to miss some
> (potentially future) service, expecting inotify to work.
> 
> Reported-by: Fiona Ebner <f.ebner@proxmox.com>

Tested-by: Fiona Ebner <f.ebner@proxmox.com>

> Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>

[pmg-devel] applied: [PATCH pmg-api v2] backup: restore: keep directories in /etc/pmg for inotify

[Thomas Lamprecht]

Am 30/11/2022 um 18:07 schrieb Stoiko Ivanov:
> By wiping the subdirectories in /etc/pmg/, we lose the inotify
> watchers upon restore (/etc/pmg itself and thus most configs are
> currently handled by the keep_root flag to rmtree)
> This can lead to inconsistencies after restoring for parts relying on
> config in a subdirectory (e.g. /etc/pmg/pbs/pbs.conf).
> 
> This patch uses File::Find (included in perl-modules-$perlver) to keep
> all directories an unlink everything else.
> This was chosen for future robustness over keeping an explicit list of
> directories to keep, in case a new directory gets added.
> 
> quickly tested with a fifo, chardev, and socket in the directory.
> 
> an alternative approach would be to simply reload pmgdaemon/pmgproxy
> upon config-restore, but that feels more likely to miss some
> (potentially future) service, expecting inotify to work.
> 
> Reported-by: Fiona Ebner <f.ebner@proxmox.com>
> Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
> ---
> v1->v2:
> * do not track an explicit list of directories, but simply keep all
>   (as suggested by Fiona)
> * use File::Find, since it's present if perl-modules is installed
> 
> I did not put this in a helper by itself in pve-common, because it seems
> short/direct enough to not warrant it.
> 
>  src/PMG/Backup.pm | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
>

applied, with Fiona's T-b, thanks!

I changed the find call to directly pass the code ref sub, as I found using
the "wanted" option not really helpful (name makes it sound like it would have
some influence on descending, but it really is just a dumb callback).

Also caught ENOENT error explicitly from the unlink invocation, while not _that_
likely IMO still a good practice.