Re: [pve-devel] [PATCH manager 1/1] pve6to7: check for containers not supporting pure cgroupv2

[Thomas Lamprecht <t.lamprecht@proxmox.com>]

On 02.07.21 20:21, Stoiko Ivanov wrote:
> Ordered as much as possible to exit early, still might take quite some
> time on systems with many containers (which do support cgroupv2).

The early abort once one is found seems like a good idea in general, but
I still do not really like that happening unconditionally, this could get hidden
behind and  opt-in CLI option flag - with a single skip log if not taken.

An admin with only bleeding-edge Arch Linux container then could then just
snicker over software from the stone age and just continue ;)

Also, you're currently missing some cheap optimizations like skipping devuan/alpine
config ostypes early, doing needless work for them.

> 
> needs a versioned bump on pve-container

I'd rather prefer copying the required helpers over, as this is mainly required
for stable-6, and it would make it way easier than having versioned dependency
handling for just this in two releases.

> 
> Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
> ---
>  PVE/CLI/pve6to7.pm | 68 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 68 insertions(+)
> 
> diff --git a/PVE/CLI/pve6to7.pm b/PVE/CLI/pve6to7.pm
> index 60edac11..3d7c67bd 100644
> --- a/PVE/CLI/pve6to7.pm
> +++ b/PVE/CLI/pve6to7.pm
> @@ -23,6 +23,9 @@ use PVE::Tools qw(run_command split_list);
>  use PVE::QemuConfig;
>  use PVE::QemuServer;
>  use PVE::VZDump::Common;
> +use PVE::LXC;
> +use PVE::LXC::Config;
> +use PVE::LXC::Setup;
>  
>  use Term::ANSIColor;
>  
> @@ -890,6 +893,70 @@ sub check_storage_content {
>  	log_pass("no problems found");
>      }
>  }
> +sub check_containers_cgroup_compat {
> +
> +    my $kernel_cli = PVE::Tools::file_get_contents('/proc/cmdline');
> +    if ($kernel_cli =~ /systemd.unified_cgroup_hierarchy=0/){
> +	log_skip("System explicitly configured for legacy hybrid cgroup hierarchy.");
> +	return;
> +    }
> +
> +    my $cts = eval { PVE::API2::LXC->vmlist({ node => $nodename }) };
> +    if ($@) {
> +	log_warn("Failed to retrieve information about this node's CTs - $@");
> +	return;
> +    }
> +
> +    if (!defined($cts) || !scalar(@$cts)) {
> +	log_skip("No containers on node detected.");
> +	return;
> +    }
> +    my @running_vmids = map { $_->{status} eq 'running' ? $_->{vmid} : () } @$cts;
> +    my @offline_vmids = map { $_->{status} ne 'running' ? $_->{vmid} : () } @$cts;

nit, but why not grep? Would make it a bit more explicit here, avoiding that any
innocent reader thinks map makes this not work and then spent time getting proved
otherwise ;-)

> +
> +    my $legacy_container=0;
> +
> +    for my $ctid (@running_vmids) {
> +	my $pid = eval { PVE::LXC::find_lxc_pid($ctid) };
> +	if (my $err = $@) {
> +	    log_warn("Failed to get PID for running CT $ctid - $err");
> +	    next;
> +	}
> +	my $rootdir = "/proc/$pid/root";
> +	my $conf = PVE::LXC::Config->load_config($ctid);
> +	my $lxc_setup = PVE::LXC::Setup->new($conf, $rootdir);
> +	if (!$lxc_setup->unified_cgroupv2_support()) {
> +	    log_warn("CT $ctid does not support running in a unified cgroup v2 layout - either " .

Maybe start with "Found at least one CT ($ctid) which does not supp...", makes the
nature of the check slightly less subtle IMO.

> +		"upgrade it or set systemd.unified_cgroup_hierarchy=0 in the kernel cmdline - "  .
> +		"skipping further checks");

> +	    return;
> +	}
> +    }
> +
> +    my $storage_cfg = PVE::Storage::config();
> +    for my $ctid (@offline_vmids) {
> +	my ($conf, $rootdir, $lxc_setup);
> +	eval {
> +	    $conf = PVE::LXC::Config->load_config($ctid);
> +	    $rootdir = PVE::LXC::mount_all($ctid, $storage_cfg, $conf);
> +	    $lxc_setup = PVE::LXC::Setup->new($conf, $rootdir);
> +	};
> +	if (my $err = $@) {
> +	    log_warn("Failed to load config and mount CT $ctid - $err");
> +	    eval { PVE::LXC::umount_all($ctid, $storage_cfg, $conf) };
> +	    next;
> +	}
> +	if (!$lxc_setup->unified_cgroupv2_support()) {
> +	    log_warn("CT $ctid does not support running in a unified cgroup v2 layout - either " .
> +		"upgrade it or set systemd.unified_cgroup_hierarchy=0 in the kernel cmdline - "  .
> +		"skipping further checks");

maybe factor out the common part of that specific log message

> +	    eval { PVE::LXC::umount_all($ctid, $storage_cfg, $conf) };
> +	    last;
> +	}
> +
> +	eval { PVE::LXC::umount_all($ctid, $storage_cfg, $conf) };
> +    }
> +};
>  
>  sub check_misc {
>      print_header("MISCELLANEOUS CHECKS");
> @@ -986,6 +1053,7 @@ sub check_misc {
>      check_custom_pool_roles();
>      check_description_lengths();
>      check_storage_content();
> +    check_containers_cgroup_compat();
>  }
>  
>  __PACKAGE__->register_method ({
>