switch-to-configuration: fix detection of changes between rebuilds for template instances

This makes declarative containers truly reloadable. Current code already declares it:

https://github.com/NixOS/nixpkgs/blob/56904d7c423f2b13b37fbd29f39bbb4b52bc7824/nixos/modules/virtualisation/containers.nix#L488

```
  restartIfChanged = false;
```

https://github.com/NixOS/nixpkgs/blob/56904d7c423f2b13b37fbd29f39bbb4b52bc7824/nixos/modules/virtualisation/containers.nix#L540

```
  reloadIfChanged = true;
```

Original author: @chrisfarms in https://github.com/NixOS/nixpkgs/pull/3021/commits/6e36619b277f78ece1bb81b79b5651897e46a2bf
Most of stuff from that commit has already been ported.
This commit is contained in:
danbst
2017-08-22 15:04:18 +03:00
parent 37c340728e
commit 65ff0d5f9d
@@ -147,11 +147,16 @@ my $activePrev = getActiveUnits;
while (my ($unit, $state) = each %{$activePrev}) {
my $baseUnit = $unit;
# Recognise template instances.
$baseUnit = "$1\@.$2" if $unit =~ /^(.*)@[^\.]*\.(.*)$/;
my $prevUnitFile = "/etc/systemd/system/$baseUnit";
my $newUnitFile = "$out/etc/systemd/system/$baseUnit";
# Detect template instances.
if (!-e $prevUnitFile && !-e $newUnitFile && $unit =~ /^(.*)@[^\.]*\.(.*)$/) {
$baseUnit = "$1\@.$2";
$prevUnitFile = "/etc/systemd/system/$baseUnit";
$newUnitFile = "$out/etc/systemd/system/$baseUnit";
}
my $baseName = $baseUnit;
$baseName =~ s/\.[a-z]*$//;