systemd: add a name option to all systemd units

This allows us to set things like dependencies in a way that we can
catch typos at eval time.
So instead of
```nix
systemd.services.foo.wants = [ "bar.service" ];
```
we can write
```nix
systemd.services.foo.wants = [ config.systemd.services.bar.name ];
```
which will throw an error if no such service has been defined.

Not all cases can be done like this (eg template services), but in a lot
of cases this will allow to avoid typos.

There is a matching option on the unit option
(`systemd.units."foo.service".name`) as well.

3 files changed, 25 insertions, 26 deletions

diff --git a/nixos/modules/system/boot/systemd.nix b/nixos/modules/system/boot/systemd.nix
index aea6855f91c50..c82924763d5e8 100644
--- a/nixos/modules/system/boot/systemd.nix
+++ b/nixos/modules/system/boot/systemd.nix
@@ -595,18 +595,17 @@ in
     };
 
     systemd.units =
-         mapAttrs' (n: v: nameValuePair "${n}.path"    (pathToUnit    n v)) cfg.paths
-      // mapAttrs' (n: v: nameValuePair "${n}.service" (serviceToUnit n v)) cfg.services
-      // mapAttrs' (n: v: nameValuePair "${n}.slice"   (sliceToUnit   n v)) cfg.slices
-      // mapAttrs' (n: v: nameValuePair "${n}.socket"  (socketToUnit  n v)) cfg.sockets
-      // mapAttrs' (n: v: nameValuePair "${n}.target"  (targetToUnit  n v)) cfg.targets
-      // mapAttrs' (n: v: nameValuePair "${n}.timer"   (timerToUnit   n v)) cfg.timers
-      // listToAttrs (map
-                   (v: let n = escapeSystemdPath v.where;
-                       in nameValuePair "${n}.mount" (mountToUnit n v)) cfg.mounts)
-      // listToAttrs (map
-                   (v: let n = escapeSystemdPath v.where;
-                       in nameValuePair "${n}.automount" (automountToUnit n v)) cfg.automounts);
+      let
+        withName = cfgToUnit: cfg: lib.nameValuePair cfg.name (cfgToUnit cfg);
+      in
+         mapAttrs' (_: withName pathToUnit) cfg.paths
+      // mapAttrs' (_: withName serviceToUnit) cfg.services
+      // mapAttrs' (_: withName sliceToUnit) cfg.slices
+      // mapAttrs' (_: withName socketToUnit) cfg.sockets
+      // mapAttrs' (_: withName targetToUnit) cfg.targets
+      // mapAttrs' (_: withName timerToUnit) cfg.timers
+      // listToAttrs (map (withName mountToUnit) cfg.mounts)
+      // listToAttrs (map (withName automountToUnit) cfg.automounts);
 
       # Environment of PID 1
       systemd.managerEnvironment = {
diff --git a/nixos/modules/system/boot/systemd/initrd.nix b/nixos/modules/system/boot/systemd/initrd.nix
index 00441b693d670..cc32b2a15e7ce 100644
--- a/nixos/modules/system/boot/systemd/initrd.nix
+++ b/nixos/modules/system/boot/systemd/initrd.nix
@@ -490,18 +490,18 @@ in {
 
       targets.initrd.aliases = ["default.target"];
       units =
-           mapAttrs' (n: v: nameValuePair "${n}.path"    (pathToUnit    n v)) cfg.paths
-        // mapAttrs' (n: v: nameValuePair "${n}.service" (serviceToUnit n v)) cfg.services
-        // mapAttrs' (n: v: nameValuePair "${n}.slice"   (sliceToUnit   n v)) cfg.slices
-        // mapAttrs' (n: v: nameValuePair "${n}.socket"  (socketToUnit  n v)) cfg.sockets
-        // mapAttrs' (n: v: nameValuePair "${n}.target"  (targetToUnit  n v)) cfg.targets
-        // mapAttrs' (n: v: nameValuePair "${n}.timer"   (timerToUnit   n v)) cfg.timers
+           mapAttrs' (n: v: nameValuePair "${n}.path"    (pathToUnit    v)) cfg.paths
+        // mapAttrs' (n: v: nameValuePair "${n}.service" (serviceToUnit v)) cfg.services
+        // mapAttrs' (n: v: nameValuePair "${n}.slice"   (sliceToUnit   v)) cfg.slices
+        // mapAttrs' (n: v: nameValuePair "${n}.socket"  (socketToUnit  v)) cfg.sockets
+        // mapAttrs' (n: v: nameValuePair "${n}.target"  (targetToUnit  v)) cfg.targets
+        // mapAttrs' (n: v: nameValuePair "${n}.timer"   (timerToUnit   v)) cfg.timers
         // listToAttrs (map
                      (v: let n = escapeSystemdPath v.where;
-                         in nameValuePair "${n}.mount" (mountToUnit n v)) cfg.mounts)
+                         in nameValuePair "${n}.mount" (mountToUnit v)) cfg.mounts)
         // listToAttrs (map
                      (v: let n = escapeSystemdPath v.where;
-                         in nameValuePair "${n}.automount" (automountToUnit n v)) cfg.automounts);
+                         in nameValuePair "${n}.automount" (automountToUnit v)) cfg.automounts);
 
       # make sure all the /dev nodes are set up
       services.systemd-tmpfiles-setup-dev.wantedBy = ["sysinit.target"];
diff --git a/nixos/modules/system/boot/systemd/user.nix b/nixos/modules/system/boot/systemd/user.nix
index 4c7b51ee22b74..2685cf7e283a2 100644
--- a/nixos/modules/system/boot/systemd/user.nix
+++ b/nixos/modules/system/boot/systemd/user.nix
@@ -175,12 +175,12 @@ in {
     };
 
     systemd.user.units =
-         mapAttrs' (n: v: nameValuePair "${n}.path"    (pathToUnit    n v)) cfg.paths
-      // mapAttrs' (n: v: nameValuePair "${n}.service" (serviceToUnit n v)) cfg.services
-      // mapAttrs' (n: v: nameValuePair "${n}.slice"   (sliceToUnit   n v)) cfg.slices
-      // mapAttrs' (n: v: nameValuePair "${n}.socket"  (socketToUnit  n v)) cfg.sockets
-      // mapAttrs' (n: v: nameValuePair "${n}.target"  (targetToUnit  n v)) cfg.targets
-      // mapAttrs' (n: v: nameValuePair "${n}.timer"   (timerToUnit   n v)) cfg.timers;
+         mapAttrs' (n: v: nameValuePair "${n}.path"    (pathToUnit    v)) cfg.paths
+      // mapAttrs' (n: v: nameValuePair "${n}.service" (serviceToUnit v)) cfg.services
+      // mapAttrs' (n: v: nameValuePair "${n}.slice"   (sliceToUnit   v)) cfg.slices
+      // mapAttrs' (n: v: nameValuePair "${n}.socket"  (socketToUnit  v)) cfg.sockets
+      // mapAttrs' (n: v: nameValuePair "${n}.target"  (targetToUnit  v)) cfg.targets
+      // mapAttrs' (n: v: nameValuePair "${n}.timer"   (timerToUnit   v)) cfg.timers;
 
     # Generate timer units for all services that have a ‘startAt’ value.
     systemd.user.timers =