Add a filesWatcher service to restart them when secrets change

[perso/Immae/Config/Nix.git] / modules / filesWatcher.nix

diff --git a/modules/filesWatcher.nix b/modules/filesWatcher.nix
new file mode 100644 (file)
index 0000000..4444027
--- /dev/null
+++ b/modules/filesWatcher.nix
@@ -0,0 +1,61 @@
+{ lib, config, pkgs, ... }:
+with lib;
+let
+  cfg = config.services.filesWatcher;
+in
+{
+  options = {
+    services.filesWatcher = with types; mkOption {
+      default = {};
+      description = ''
+        Files to watch and trigger service reload or restart of service
+        when changed.
+        '';
+        type = attrsOf (submodule {
+          options = {
+            restart = mkEnableOption "Restart service rather than reloading it";
+            paths = mkOption {
+              type = listOf str;
+              description = ''
+                Paths to watch that should trigger a reload of the
+                service
+                '';
+            };
+            waitTime = mkOption {
+              type = int;
+              default = 5;
+              description = ''
+                Time to wait before reloading/restarting the service.
+                Set 0 to not wait.
+                '';
+            };
+          };
+      });
+    };
+  };
+
+  config.systemd.services = attrsets.mapAttrs' (name: icfg: attrsets.nameValuePair
+    "${name}Watcher" {
+      description = "${name} reloader";
+      after = [ "network.target" ];
+      script = let
+        action = if icfg.restart then "restart" else "reload";
+      in ''
+        # Service may be stopped during file modification (e.g. activationScripts)
+        if ${pkgs.systemd}/bin/systemctl --quiet is-active ${name}.service; then
+          ${pkgs.coreutils}/bin/sleep ${toString icfg.waitTime}
+          ${pkgs.systemd}/bin/systemctl ${action} ${name}.service
+        fi
+        '';
+      serviceConfig = {
+        Type = "oneshot";
+      };
+    }
+  ) cfg;
+  config.systemd.paths = attrsets.mapAttrs' (name: icfg: attrsets.nameValuePair
+    "${name}Watcher" {
+      wantedBy = [ "multi-user.target" ];
+      pathConfig.PathChanged = icfg.paths;
+    }
+  ) cfg;
+}