[pve-devel] [RFC guest-common 3/3] fix 3111: replicate guest on rollback if there are replication jobs for it

[Fabian Ebner]

so that there will be a valid replication snapshot again.

Otherwise, replication will be broken after a rollback if the last
(non-replication) snapshot is removed before replication can run once.

Signed-off-by: Fabian Ebner <f.ebner at proxmox.com>
---

Not a huge fan of this, but the alternatives I could come up with don't seem
much better IMHO:

1. Invalidate/remove replicated volumes after a rollback altogether and require
a full sync on the next replication job afterwards.

2. Another one is to disallow removing the last non-replication snapshot if:
    * there is a replication job configured
    * no replication snapshot for that job currently exists (which likely
      means it was removed by a previous rollback operation, but can also happen
      for a new job that didn't run yet).

3. Hope not very many people immediately delete their snapshots after rollback.

Pick a favorite or suggest your own ;)

 PVE/AbstractConfig.pm    | 19 +++++++++++++++++--
 PVE/ReplicationConfig.pm | 14 ++++++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/PVE/AbstractConfig.pm b/PVE/AbstractConfig.pm
index c4d1d6c..b169b8b 100644
--- a/PVE/AbstractConfig.pm
+++ b/PVE/AbstractConfig.pm
@@ -951,6 +951,9 @@ sub snapshot_rollback {
 
     my $storecfg = PVE::Storage::config();
 
+    my $repl_conf = PVE::ReplicationConfig->new();
+    my $logfunc = sub { my $line = shift; chomp $line; print "$line\n"; };
+
     my $data = {};
 
     my $get_snapshot_config = sub {
@@ -972,7 +975,6 @@ sub snapshot_rollback {
 	$snap = $get_snapshot_config->($conf);
 
 	if ($prepare) {
-	    my $repl_conf = PVE::ReplicationConfig->new();
 	    if ($repl_conf->check_for_existing_jobs($vmid, 1)) {
 		# remove replication snapshots on volumes affected by rollback *only*!
 		my $volumes = $class->get_replicatable_volumes($storecfg, $vmid, $snap, 1);
@@ -988,7 +990,6 @@ sub snapshot_rollback {
 		});
 
 		# remove all local replication snapshots (jobid => undef)
-		my $logfunc = sub { my $line = shift; chomp $line; print "$line\n"; };
 		PVE::Replication::prepare($storecfg, $volids, undef, 1, undef, $logfunc);
 	    }
 
@@ -1046,6 +1047,20 @@ sub snapshot_rollback {
 
     $prepare = 0;
     $class->lock_config($vmid, $updatefn);
+
+    my $replication_jobs = $repl_conf->list_guests_replication_jobs($vmid);
+    for my $job (@{$replication_jobs}) {
+	my $target = $job->{target};
+	$logfunc->("replicating rolled back guest to node '$target'");
+
+	my $start_time = time();
+	eval {
+	    PVE::Replication::run_replication($class, $job, $start_time, $start_time, $logfunc);
+	};
+	if (my $err = $@) {
+	    warn "unable to replicate rolled back guest to node '$target' - $err";
+	}
+    }
 }
 
 # bash completion helper
diff --git a/PVE/ReplicationConfig.pm b/PVE/ReplicationConfig.pm
index fd856a0..84a718f 100644
--- a/PVE/ReplicationConfig.pm
+++ b/PVE/ReplicationConfig.pm
@@ -228,6 +228,20 @@ sub find_local_replication_job {
     return undef;
 }
 
+sub list_guests_replication_jobs {
+    my ($cfg, $vmid) = @_;
+
+    my $jobs = [];
+
+    for my $job (values %{$cfg->{ids}}) {
+	next if $job->{type} ne 'local' || $job->{guest} != $vmid;
+
+	push @{$jobs}, $job;
+    }
+
+    return $jobs;
+}
+
 # makes old_target the new source for all local jobs of this guest
 # makes new_target the target for the single local job with target old_target
 sub switch_replication_job_target_nolock {
-- 
2.20.1