Restic: made modular backup declerations.

Required tree-wide re-wiring of the host option.
Now, rather than each host having a monolithic restic.nix file,
the hosts restic.nix file just specifies the password and url of the
restic repository. Eatch module then definies specific paths to backup
and any pre and post commands that need to be performed.
Each backed up service gets an independent systemd backup service and
timer.

modules/nixos/default.nix

@@ -1,5 +1,6 @@
 {
   imports = [
     ./hostopts.nix
+    ./restic.nix
   ];
 }

modules/nixos/hostopts.nix

@@ -5,7 +5,7 @@
   ...
 }: {
   options = {
-    host = {
+    host.details = {
       user = lib.mkOption {
         type = lib.types.str;
         description = "Primary human user";

modules/nixos/restic.nix

@@ -0,0 +1,148 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}: {
+  options = {
+    host.restic = {
+      enable = lib.mkEnableOption "enable restic";
+      passwordFile = lib.mkOption {
+        type = lib.types.path;
+        description = "path to the file containing the restic repository password.";
+      };
+      repositoryFile = lib.mkOption {
+        type = lib.types.nullOr lib.types.path;
+        description = "path to the file containing the restic repository url/path";
+        default = null;
+      };
+      repository = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        description = "restic repository url/path";
+      };
+      server = {
+        enable = lib.mkEnableOption "enable restic server (must have nginx enabled and setup, and host.restic.passwordFile populated.)";
+        repositoryPath = lib.mkOption {
+          type = lib.types.path;
+          description = "path of repository";
+        };
+        htpasswdPath = lib.mkOption {
+          type = lib.types.path;
+          description = "path to the repositories .htpasswd file";
+        };
+        domain = lib.mkOption {
+          type = lib.types.str;
+          description = "domain name to serve the restic server under. (for nginx virtualHosts)";
+        };
+        port = lib.mkOption {
+          type = lib.types.str;
+          description = "(internal) port to use between nginx and restic-server";
+        };
+      };
+      backups = lib.mkOption {
+        description = "backups to create";
+        default = {};
+        type = lib.types.attrsOf (lib.types.submodule ({name, ...}: {
+          options = {
+            paths = lib.mkOption {
+              type = lib.types.listOf lib.types.path;
+              description = "paths to back up.";
+            };
+            preBackupCommands = lib.mkOption {
+              type = lib.types.nullOr lib.types.lines;
+              description = "commands to run before the start of the backup.";
+              default = null;
+            };
+            postBackupCommands = lib.mkOption {
+              type = lib.types.nullOr lib.types.lines;
+              description = "commands to run after the backup is finished.";
+              default = null;
+            };
+          };
+        }));
+      };
+    };
+  };
+  config = let
+    cfg = config.host.restic;
+    timer = {
+      OnCalendar = "daily";
+      Persistent = true;
+      RandomizedDelaySec = "4h";
+    };
+    pruneOpts = [
+      "--keep-within 14d"
+      "--keep-daily 14"
+      "--keep-weekly 8"
+      "--keep-monthly 12"
+      "--keep-yearly 10"
+    ];
+  in {
+    environment.systemPackages =
+      lib.mkIf
+      (cfg.server.enable || cfg.enable)
+      (with pkgs; [
+        restic
+      ]);
+
+    services.restic.server = lib.mkIf cfg.server.enable {
+      enable = true;
+      appendOnly = true;
+      dataDir = cfg.server.repositoryPath;
+      listenAddress = "127.0.0.1:${cfg.server.port}";
+      extraFlags = ["--htpasswd-file '${cfg.server.htpasswdPath}'"];
+    };
+
+    services.nginx.virtualHosts =
+      lib.mkIf (
+        cfg.server.enable
+        && (lib.asserts.assertMsg
+          (config.services.nginx.enable == true)
+          "NGINX must be enabled")
+      )
+      {
+        "${cfg.server.domain}" = {
+          enableACME = lib.asserts.assertMsg (
+            config.security.acme.acceptTerms
+            == true
+            && config.security.acme.defaults.email != null
+          ) "ACME must be setup";
+          forceSSL = true;
+          locations."/" = {
+            proxyPass = "http://localhost:${cfg.server.port}";
+          };
+        };
+      };
+
+    services.restic.backups = lib.mkMerge [
+      (lib.mkIf cfg.server.enable {
+        prune = {
+          repository = cfg.server.repositoryPath;
+          passwordFile = cfg.passwordFile;
+          initialize = true;
+          runCheck = true;
+          paths = null;
+          timerConfig = timer;
+          pruneOpts = pruneOpts;
+        };
+      })
+      (
+        lib.mkIf cfg.enable (
+          lib.mapAttrs (
+            name: backup: {
+              repositoryFile = cfg.repositoryFile;
+              repository = cfg.repository;
+              passwordFile = cfg.passwordFile;
+              timerConfig = timer;
+              backupPrepareCommand = backup.preBackupCommands;
+              backupCleanupCommand = backup.postBackupCommands;
+              paths = backup.paths;
+            }
+          )
+          cfg.backups
+        )
+      )
+    ];
+  };
+}