diff --git a/flake.lock b/flake.lock
index a9548faf..0397847a 100644
--- a/flake.lock
+++ b/flake.lock
@@ -244,26 +244,6 @@
         "type": "github"
       }
     },
-    "flake-parts": {
-      "inputs": {
-        "nixpkgs-lib": [
-          "nixos"
-        ]
-      },
-      "locked": {
-        "lastModified": 1683560683,
-        "narHash": "sha256-XAygPMN5Xnk/W2c1aW0jyEa6lfMDZWlQgiNtmHXytPc=",
-        "owner": "hercules-ci",
-        "repo": "flake-parts",
-        "rev": "006c75898cf814ef9497252b022e91c946ba8e17",
-        "type": "github"
-      },
-      "original": {
-        "owner": "hercules-ci",
-        "repo": "flake-parts",
-        "type": "github"
-      }
-    },
     "flake-utils": {
       "inputs": {
         "systems": "systems"
@@ -282,33 +262,6 @@
         "type": "github"
       }
     },
-    "harmonia": {
-      "inputs": {
-        "flake-parts": [
-          "flake-parts"
-        ],
-        "nixpkgs": [
-          "nixos"
-        ],
-        "treefmt-nix": [
-          "treefmt-nix"
-        ]
-      },
-      "locked": {
-        "lastModified": 1680558002,
-        "narHash": "sha256-qDo6tT8yUVk4m+2LLcTLPeGXi57oEnisZ0dVhTdfBZQ=",
-        "owner": "SuperSandro2000",
-        "repo": "harmonia",
-        "rev": "5a4eb53e61b873530ff90fed805546a6f995b9e1",
-        "type": "github"
-      },
-      "original": {
-        "owner": "SuperSandro2000",
-        "ref": "flake-lock",
-        "repo": "harmonia",
-        "type": "github"
-      }
-    },
     "heliwatch": {
       "inputs": {
         "fenix": [
@@ -405,11 +358,11 @@
     },
     "nixos": {
       "locked": {
-        "lastModified": 1683577441,
-        "narHash": "sha256-eXB8x4N3GKXqAF5aGKx5tytCLI/z+2ByL1q31QCd+jA=",
+        "lastModified": 1683581121,
+        "narHash": "sha256-4OQZS2Rf0SZ8yjFRnZyx9QfX022oVOBNr0bjHjchpDk=",
         "owner": "SuperSandro2000",
         "repo": "nixpkgs",
-        "rev": "e3340c4e4c65b194fa2ced32ac5ee6439163763b",
+        "rev": "4c72e4502094cf5ec5279e1f22a809b8f3db71d9",
         "type": "github"
       },
       "original": {
@@ -520,9 +473,7 @@
         "deployment": "deployment",
         "disko": "disko",
         "fenix": "fenix",
-        "flake-parts": "flake-parts",
         "flake-utils": "flake-utils",
-        "harmonia": "harmonia",
         "heliwatch": "heliwatch",
         "microvm": "microvm",
         "naersk": "naersk",
@@ -542,7 +493,6 @@
         "ticker": "ticker",
         "tigger": "tigger",
         "tracer": "tracer",
-        "treefmt-nix": "treefmt-nix",
         "yammat": "yammat",
         "zentralwerk": "zentralwerk"
       }
@@ -795,26 +745,6 @@
         "url": "https://gitea.c3d2.de/astro/tracer"
       }
     },
-    "treefmt-nix": {
-      "inputs": {
-        "nixpkgs": [
-          "nixos"
-        ]
-      },
-      "locked": {
-        "lastModified": 1683307174,
-        "narHash": "sha256-A7nF2Q+F+Bqs4u6VS4aOzyURfly5f4ZAiihGU0FA29g=",
-        "owner": "numtide",
-        "repo": "treefmt-nix",
-        "rev": "b44794f94514b61512352a18cd77c710f0005f15",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "treefmt-nix",
-        "type": "github"
-      }
-    },
     "yammat": {
       "inputs": {
         "nixpkgs": [
diff --git a/flake.nix b/flake.nix
index 973806f9..67deff55 100644
--- a/flake.nix
+++ b/flake.nix
@@ -83,20 +83,7 @@
       url = "github:nix-community/fenix/monthly";
       inputs.nixpkgs.follows = "nixos";
     };
-    flake-parts = {
-      url = "github:hercules-ci/flake-parts";
-      inputs.nixpkgs-lib.follows = "nixos";
-    };
     flake-utils.url = "github:numtide/flake-utils";
-    # TODO: drop when switching to 23.05 and check if treefmt-nix is still used
-    harmonia = {
-      url = "github:SuperSandro2000/harmonia/flake-lock";
-      inputs = {
-        flake-parts.follows = "flake-parts";
-        nixpkgs.follows = "nixos";
-        treefmt-nix.follows = "treefmt-nix";
-      };
-    };
     heliwatch = {
       url = "git+https://gitea.c3d2.de/astro/heliwatch.git";
       inputs = {
@@ -201,10 +188,6 @@
         flake-utils.follows = "flake-utils";
       };
     };
-    treefmt-nix = {
-      url = "github:numtide/treefmt-nix";
-      inputs.nixpkgs.follows = "nixos";
-    };
     yammat = {
       url = "git+https://gitea.c3d2.de/c3d2/yammat.git";
       inputs.nixpkgs.follows = "nixos";
@@ -219,7 +202,7 @@
     };
   };
 
-  outputs = inputs@{ self, alert2muc, c3d2-user-module, deployment, fenix, harmonia, heliwatch, microvm, naersk, nixos, nixos-hardware, nixos-modules, buzzrelay, caveman, oparl-scraper, scrapers, secrets, skyflake, sshlogd, sops-nix, spacemsg, ticker, tigger, yammat, zentralwerk, ... }:
+  outputs = inputs@{ self, alert2muc, c3d2-user-module, deployment, fenix, heliwatch, microvm, naersk, nixos, nixos-hardware, nixos-modules, buzzrelay, caveman, oparl-scraper, scrapers, secrets, skyflake, sshlogd, sops-nix, spacemsg, ticker, tigger, yammat, zentralwerk, ... }:
     let
       inherit (nixos) lib;
 
@@ -423,17 +406,7 @@
           modules = [
             self.nixosModules.cluster
             skyflake.nixosModules.default
-            harmonia.nixosModules.harmonia
             ./hosts/hydra
-            {
-              nixpkgs.overlays = [
-                (final: prev: with final; {
-                  harmonia = harmonia.packages.${system}.harmonia.override {
-                    pkgs = prev // { inherit (rustPackages_1_66) rustPlatform; };
-                  };
-                })
-              ];
-            }
           ];
         };
 
@@ -777,6 +750,7 @@
             ./modules/autoupdate.nix
             ./modules/backup.nix
             ./modules/c3d2.nix
+            ./modules/disko.nix
             ./modules/nncp.nix
             ./modules/plume.nix
             ./modules/stats.nix
diff --git a/hosts/hydra/default.nix b/hosts/hydra/default.nix
index 3e82d1c2..bad4bf33 100644
--- a/hosts/hydra/default.nix
+++ b/hosts/hydra/default.nix
@@ -199,8 +199,8 @@ in
         workers = 20;
         max_connection_rate = 1024;
         priority = 50;
-        sign_key_path = config.sops.secrets."nix/signing-key/secretKey".path;
       };
+      signKeyPath = config.sops.secrets."nix/signing-key/secretKey".path;
     };
 
     nginx = {
@@ -337,7 +337,4 @@ in
       MemorySwapMax = "64G";
     };
   };
-
-  # allow reading harmonia secret
-  users.users.harmonia.extraGroups = [ "hydra" ];
 }