[pve-devel] [PATCH V2 qemu-server] fix #1739: cloudinit: add cisshdeletehostkeys option

[Alexandre Derumier <aderumier@odiso.com>]

This define behaviour of ssh server keys generation on cloudinit
config change.

different value:

- once : only once at vmstart  (default value)
- no|off|false : never generate ssh key
- yes|on|true: always generate ssh key

When value is defined to 'once', the value is rewriten to 'no'
in vmconfig after vm start

We need to change instance-id at each config change because
network configuration is only done once in pre-init local service,
and a lock is done on instance-id, and they are no way to change
that in cloudinit vm config.

The ssh host keys are regenerated by ssh module, once by instance.
user could change that,and do only once,
but in this same ssh module, the user public keys are also deployed.

Signed-off-by: Alexandre Derumier <aderumier@odiso.com>
---
 PVE/QemuServer.pm           |  9 ++++++++-
 PVE/QemuServer/Cloudinit.pm | 10 +++++++++-
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index f401baf..c899b35 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -760,6 +760,13 @@ my $confdesc_cloudinit = {
 	format => 'urlencoded',
 	description => "cloud-init: Setup public SSH keys (one key per line, OpenSSH format).",
     },
+    cisshdeletehostkeys => {
+	optional => 1,
+	type => 'string',
+	enum => [qw(once yes no on off true false)],
+	default_key => 1,
+	description => "cloud-init: Regenerate host SSH keys on config change.",
+    },
 };
 
 # what about other qemu settings ?
@@ -4951,7 +4958,7 @@ sub vm_start_nolock {
 	$conf = PVE::QemuConfig->load_config($vmid); # update/reload
     }
 
-    PVE::QemuServer::Cloudinit::generate_cloudinitconfig($conf, $vmid);
+    PVE::QemuServer::Cloudinit::generate_cloudinitconfig($conf, $vmid, 1);
 
     my $defaults = load_defaults();
 
diff --git a/PVE/QemuServer/Cloudinit.pm b/PVE/QemuServer/Cloudinit.pm
index c464bf3..7b24f93 100644
--- a/PVE/QemuServer/Cloudinit.pm
+++ b/PVE/QemuServer/Cloudinit.pm
@@ -135,6 +135,7 @@ sub cloudinit_userdata {
 	foreach my $k (@$keys) {
 	    $content .= "  - $k\n";
 	}
+	$content .= "ssh_deletekeys: false\n" if defined($conf->{cisshdeletehostkeys}) && $conf->{cisshdeletehostkeys} =~ m/^(off|no|false)/; 
     }
     $content .= "chpasswd:\n";
     $content .= "  expire: False\n";
@@ -554,9 +555,10 @@ my $cloudinit_methods = {
 };
 
 sub generate_cloudinitconfig {
-    my ($conf, $vmid) = @_;
+    my ($conf, $vmid, $vmstart) = @_;
 
     my $format = get_cloudinit_format($conf);
+    my $generated = undef;
 
     PVE::QemuConfig->foreach_volume($conf, sub {
         my ($ds, $drive) = @_;
@@ -569,7 +571,13 @@ sub generate_cloudinitconfig {
 	    or die "missing cloudinit methods for format '$format'\n";
 
 	$generator->($conf, $vmid, $drive, $volname, $storeid);
+	$generated = 1;
     });
+
+    if ($vmstart && $generated && (!defined($conf->{cisshdeletehostkeys}) || $conf->{cisshdeletehostkeys} eq 'once')) {
+	$conf->{cisshdeletehostkeys} = 'no';
+	PVE::QemuConfig->write_config($vmid, $conf);
+    }
 }
 
 sub dump_cloudinit_config {
-- 
2.20.1