flip dependencies for triggered/controlled services

Instead of treating the trigger as the "main" service and the
triggered service as subsidary, now we treat the triggered
service as the service and the trigger as "subsidary". This
needs some special handling when we work out which services
go in the default bundle, but it works better for declaring
dependencies on triggered services because it means the
dependency runs after the triggered service comes up, not
just when the watcher-for-events starts

modules/mount/service.nix

@@ -7,19 +7,21 @@
 let
   inherit (liminix.services) longrun oneshot;
   device = "/dev/disk/by-partlabel/${partlabel}";
+  name = "mount.${lib.strings.sanitizeDerivationName (lib.escapeURL mountpoint)}";
   options_string =
     if options == [] then "" else "-o ${lib.concatStringsSep "," options}";
-  mount_service = oneshot {
-    name = "mount.${lib.escapeURL mountpoint}";
-    timeout-up = 3600;
-    up = "mount -t ${fstype} ${options_string} ${device} ${mountpoint}";
-    down = "umount ${mountpoint}";
-  };
-in svc.uevent-rule.build {
-  service = mount_service;
-  symlink = device;
-  terms = {
-    partname = partlabel;
-    devtype = "partition";
+  controller = svc.uevent-rule.build {
+    serviceName = name;
+    symlink = device;
+    terms = {
+      partname = partlabel;
+      devtype = "partition";
+    };
   };
+in oneshot {
+  inherit name;
+  timeout-up = 3600;
+  up = "mount -t ${fstype} ${options_string} ${device} ${mountpoint}";
+  down = "umount ${mountpoint}";
+  inherit controller;
 }

modules/s6/default.nix

@@ -13,7 +13,10 @@ let
     let
       defaultDefaultTarget = bundle {
         name = "default";
-        contents = builtins.attrValues config.services;
+        contents =
+          builtins.map
+            (s: if (s ? controller && s.controller != null) then s.controller else s)
+            (builtins.attrValues config.services));
       };
       servicesAttrs = {
         default = defaultDefaultTarget;

modules/service-trigger/default.nix

@@ -15,9 +15,9 @@ in {
   };
   config = {
     system.service.uevent-rule = liminix.callService ./rule.nix {
-      service = mkOption {
-        description = "the service to run when the rule matches";
-        type = liminix.lib.types.service;
+      serviceName = mkOption {
+        description = "name of the service to run when the rule matches";
+        type = types.str;
       };
       terms = mkOption {
         type = types.attrs;

modules/service-trigger/rule.nix

@@ -4,7 +4,7 @@
 , serviceFns
 , lib }:
 {
-  service, terms, symlink
+  serviceName, terms, symlink
 }:
 let
   inherit (liminix.services) longrun;
@@ -18,8 +18,7 @@ let
           attrs));
   termsString = stringify terms;
 in longrun {
-  name = "watch-for-${service.name}";
+  name = "watch-for-${serviceName}";
   isTrigger = true;
-  buildInputs = [ service ];
-  run = "${uevent-watch}/bin/uevent-watch ${if symlink != null then "-n ${symlink}" else ""} -s ${service.name} ${termsString}";
+  run = "${uevent-watch}/bin/uevent-watch ${if symlink != null then "-n ${symlink}" else ""} -s ${serviceName} ${termsString}";
 }

pkgs/liminix-tools/services/builder.sh

@@ -11,7 +11,7 @@ test -n "$contents" && for d in $contents; do
     touch $out/${name}/contents.d/$d
 done
 
-for i in timeout-up timeout-down run notification-fd up down finish consumer-for producer-for pipeline-name restart-on-upgrade; do
+for i in controllerName timeout-up timeout-down run notification-fd up down finish consumer-for producer-for pipeline-name restart-on-upgrade; do
     test -n "$(printenv $i)" && (echo "$(printenv $i)" > $out/${name}/$i)
 done
 

pkgs/liminix-tools/services/default.nix

@@ -39,6 +39,7 @@ let
     , contents ? []
     , buildInputs ? []
     , isTrigger ? false
+    , controller ? null
   } @ args:
     stdenvNoCC.mkDerivation {
       # we use stdenvNoCC to avoid generating derivations with names
@@ -46,9 +47,11 @@ let
       inherit name serviceType up down run finish notification-fd
         producer-for consumer-for pipeline-name timeout-up timeout-down;
       restart-on-upgrade = isTrigger;
-      buildInputs = buildInputs ++ dependencies ++ contents;
+      buildInputs = buildInputs ++ dependencies ++ contents ++ lib.optional (controller != null) controller;
       dependencies = map (d: d.name) dependencies;
       contents = map (d: d.name) contents;
+      inherit controller;
+      controllerName = if controller ? name then controller.name else null;
       builder = ./builder.sh;
     };