add kopia module

1 files changed, 76 insertions, 0 deletions

diff --git a/modules/backup/snapshot.nix b/modules/backup/snapshot.nix
new file mode 100644
index 0000000..91076cf
--- /dev/null
+++ b/modules/backup/snapshot.nix
@@ -0,0 +1,76 @@
+{
+  pkgs,
+  lib,
+  config,
+  mkInstanceServices,
+  ...
+}:
+let
+  instanceType = lib.types.submodule {
+    options = {
+      path = lib.mkOption {
+        type = lib.types.str;
+        default = "/persistent";
+        description = "snapshoted path for kopia instance.";
+      };
+      schedule = lib.mkOption {
+        type = lib.types.str;
+        default = "daily";
+        description = "Snapshot schedule for the Kopia instance.";
+      };
+    };
+  };
+in
+{
+  options.services.kopia.instances = lib.mkOption {
+    type = lib.types.attrsOf instanceType;
+  };
+
+  config = lib.mkIf config.services.kopia.enable (
+    let
+      mkSnapshotService =
+        # refactor with mkRepositoryArgs
+        name: instance:
+        lib.attrsets.nameValuePair "kopia-snapshot-${name}" {
+          description = "Kopia S3 snapshot service";
+          wants = [
+            "kopia-repository-${name}.service"
+          ];
+          after = [ "kopia-repository-${name}.service" ];
+          script = ''
+            ${pkgs.kopia}/bin/kopia snapshot create ${instance.path} --description "Snapshot for ${name}"
+          '';
+          serviceConfig = {
+            Type = "simple";
+            User = "${instance.user}";
+            WorkingDirectory = "~";
+            SetLoginEnvironment = true;
+            # retry on failure
+            Restart = "on-failure";
+            # wait 30 seconds before restarting
+            RestartSec = "30";
+            # limit the number of restarts to 5 in 1 day
+            StartLimitInterval = "1d";
+            StartLimitBurst = "5";
+            # lower priority
+            Nice = "-19";
+            IOSchedulingClass = "idle";
+          };
+        };
+      mkSnapshotTimer =
+        name: instance:
+        lib.attrsets.nameValuePair "kopia-snapshot-${name}" {
+          description = "Kopia S3 snapshot timer";
+          wantedBy = [ "timers.target" ];
+          timerConfig = {
+            OnCalendar = instance.schedule;
+          };
+        };
+    in
+    {
+      # systemd service for repositories open
+      systemd.services = mkInstanceServices config.services.kopia.instances mkSnapshotService;
+      systemd.timers = mkInstanceServices config.services.kopia.instances mkSnapshotTimer;
+    }
+  );
+}