From e3b90b6ccc4cf4147fd01df1ed8779b1c85744bd Mon Sep 17 00:00:00 2001
From: "Adrian Parvin D. Ouano" <me@adrianpar.vin>
Date: Tue, 9 Mar 2021 23:04:58 +0800
Subject: [PATCH] nixos/systemd: Handle template overrides
Adding template overrides allows for custom behavior for specific
instances of a template. Previously, it was not possible to provide
bind mounts for systemd-nspawn. This change allows it.
---
nixos/modules/system/boot/systemd-lib.nix | 13 ++++++-
nixos/tests/systemd-template-override.nix | 41 +++++++++++++++++++++++
2 files changed, 53 insertions(+), 1 deletion(-)
create mode 100644 nixos/tests/systemd-template-override.nix
diff --git a/nixos/modules/system/boot/systemd-lib.nix b/nixos/modules/system/boot/systemd-lib.nix
index 2dbf15031a0..6051a428574 100644
--- a/nixos/modules/system/boot/systemd-lib.nix
+++ b/nixos/modules/system/boot/systemd-lib.nix
@@ -182,7 +182,18 @@ in rec {
# upstream unit.
for i in ${toString (mapAttrsToList (n: v: v.unit) units)}; do
fn=$(basename $i/*)
- if [ -e $out/$fn ]; then
+
+ case $fn in
+ # if file name is a template specialization, use the template's name
+ *@?*.service)
+ # remove @foo.service and replace it with @.service
+ ofn="''${fn%@*.service}@.service"
+ ;;
+ *)
+ ofn="$fn"
+ esac
+
+ if [ -e $out/$ofn ]; then
if [ "$(readlink -f $i/$fn)" = /dev/null ]; then
ln -sfn /dev/null $out/$fn
else
diff --git a/nixos/tests/systemd-template-override.nix b/nixos/tests/systemd-template-override.nix
new file mode 100644
index 00000000000..d8ef4a6c1c9
--- /dev/null
+++ b/nixos/tests/systemd-template-override.nix
@@ -0,0 +1,41 @@
+import ./make-test-python.nix {
+ name = "systemd-template-override";
+
+ machine = { pkgs, lib, ... }: let
+ touchTmp = pkgs.writeTextFile {
+ name = "touch-tmp@.service";
+ text = ''
+ [Service]
+ Type=oneshot
+ ExecStart=${pkgs.coreutils}/bin/touch /tmp/%I
+ '';
+ destination = "/etc/systemd/system/touch-tmp@.service";
+ };
+ in {
+ systemd.packages = [ touchTmp ];
+
+ systemd.services."touch-tmp@forbidden" = {
+ serviceConfig.ExecStart = [ "" ''
+ ${pkgs.coreutils}/bin/true
+ ''];
+ };
+
+ systemd.services."touch-tmp@intercept" = {
+ serviceConfig.ExecStart = [ "" ''
+ ${pkgs.coreutils}/bin/touch /tmp/renamed
+ ''];
+ };
+ };
+
+ testScript = ''
+ machine.wait_for_unit("default.target")
+
+ machine.succeed("systemctl start touch-tmp@normal")
+ machine.succeed("systemctl start touch-tmp@forbbidden")
+ machine.succeed("systemctl start touch-tmp@intercept")
+
+ machine.succeed("[ -e /tmp/normal ]")
+ machine.succeed("[ ! -e /tmp/forbidden ]")
+ machine.succeed("[ -e /tmp/renamed ]")
+ '';
+}