postgres: create daily backups

configuration.nix

@@ -76,6 +76,7 @@
       repo = (lib.removeSuffix "\n" (builtins.readFile ./borg-backup-repo));
       paths = [
         "/var/lib/matrix-synapse"
+        "/var/backup/postgresql"
       ];
       exclude = [];
     };

services/matrix.nix

@@ -28,6 +28,13 @@ in {
       package = pkgs.postgresql_12;
     };
 
+    services.postgresqlBackup = {
+      enable = true;
+      databases = [ "matrix-synapse" ];
+      # Borg backup starts at midnight so create DB dump just before
+      startAt = "*-*-* 23:30:00";
+    };
+
     services.matrix-synapse = {
       enable = true;
       server_name = domain;