[pve-devel] applied: [PATCH container] poststop: reboot: wait for lxc to exit before rebooting

[Fabian Grünbichler]

On Thu, Mar 09, 2017 at 02:54:28PM +0100, Wolfgang Bumiller wrote:
> otherwise it'll leak cgroup directories...
> 
> Note that we need to escape the lxc at .service context (by
> entering a new scope) as well as close our ties to the lxc
> monitor (the stdout pipe), otherwise this never finishes
> properly.

looks good to me, unless there are objections this should probably go to
no-subscription on monday..

> ---
>  src/lxc-pve-poststop-hook | 35 +++++++++++++++++++++++++++++++++--
>  1 file changed, 33 insertions(+), 2 deletions(-)
> 
> diff --git a/src/lxc-pve-poststop-hook b/src/lxc-pve-poststop-hook
> index a4302d6..e3a8956 100755
> --- a/src/lxc-pve-poststop-hook
> +++ b/src/lxc-pve-poststop-hook
> @@ -9,6 +9,7 @@ exit 0 if $ENV{LXC_NAME} && $ENV{LXC_NAME} !~ /^\d+$/;
>  
>  use POSIX;
>  use File::Path;
> +use IO::Pipe;
>  
>  use PVE::SafeSyslog;
>  use PVE::Tools;
> @@ -81,9 +82,39 @@ __PACKAGE__->register_method ({
>  	    # that we must not block because we're part of the service cgroup
>  	    # systemd waits for to die before issuing the new lxc-start command.
>  	    PVE::LXC::update_lxc_config($vmid, $conf);
> -	    PVE::Tools::run_command(['systemctl', '--no-block', 'restart', "lxc\@$vmid"]);
> +	    $SIG{HUP} = 'IGNORE';
> +	    # Synchronization pipe
> +	    my $scope = IO::Pipe->new() or die "pipe failed: $!\n";
> +	    my $pid = fork();
> +	    die "fork failed: $!\n" if !defined($pid);
> +	    if (!$pid) {
> +		$scope->writer();
> +		# We inherit a pipe from LXC, replace it with stderr otherwise
> +		# lxc will keep waiting for us...
> +		POSIX::dup2(2, 1);
> +		POSIX::setsid();
> +		eval {
> +		    # Change scope otherwise we're part of lxc at .service and then
> +		    # if lxc finishes cleaning up before we restart it systemd
> +		    # might clean US up as well (read: kill us) => race
> +		    PVE::Tools::enter_systemd_scope("restart-$vmid", "Restarter for Proxmox VE CT $vmid",
> +		        Slice => 'lxc.slice',
> +		        KillMode => 'none');
> +		    # Tell the main stop hook we're "in the clear":
> +		    close($scope);
> +		    # Wait for the container to clean up everything...
> +		    PVE::Tools::run_command(['lxc-wait', "--name=$vmid", '--state=STOPPED']);
> +		    # ... before finally triggering a restart:
> +		    PVE::Tools::run_command(['systemctl', 'restart', "lxc\@$vmid"]);
> +		};
> +		warn "$@" if $@;
> +		POSIX::_exit(0);
> +	    }
> +	    # Wait for the restarter scope to make sure systemd doesn't kill it before it started...
> +	    $scope->reader();
> +	    <$scope>;
>  	    # cause lxc to stop instead of rebooting
> -	    POSIX::_exit(1);
> +	    exit(1);
>  	}
>  
>  	return undef;
> -- 
> 2.1.4
> 
> 
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