diff --git a/lib/fudo/client/dns.nix b/lib/fudo/client/dns.nix
index 68adf81..cdd5a5c 100644
--- a/lib/fudo/client/dns.nix
+++ b/lib/fudo/client/dns.nix
@@ -80,11 +80,7 @@ in {
         };
       };
 
-      groups = {
-        "${cfg.user}" = {
-          members = [ cfg.user ];
-        };
-      };
+      groups = { "${cfg.user}" = { members = [ cfg.user ]; }; };
     };
 
     systemd = {
@@ -104,7 +100,7 @@ in {
 
       services.backplane-dns-client-pw-file = {
         enable = true;
-        requiredBy = [ "backplane-dns-client.services" ];
+        requiredBy = [ "backplane-dns-client.service" ];
         reloadIfChanged = true;
         serviceConfig = { Type = "oneshot"; };
         script = ''
diff --git a/lib/fudo/prometheus.nix b/lib/fudo/prometheus.nix
index 87aabd8..dbecdc0 100644
--- a/lib/fudo/prometheus.nix
+++ b/lib/fudo/prometheus.nix
@@ -8,6 +8,13 @@ in {
   options.fudo.metrics.prometheus = with types; {
     enable = mkEnableOption "Fudo Prometheus Data-Gathering Server";
 
+    package = mkOption {
+      type = package;
+      default = pkgs.prometheus;
+      defaultText = literalExpression "pkgs.prometheus";
+      description = "The prometheus package that should be used.";
+    };
+
     service-discovery-dns = mkOption {
       type = attrsOf (listOf str);
       description = ''
@@ -119,9 +126,10 @@ in {
     services.prometheus = {
 
       enable = true;
-
       webExternalUrl = "https://${cfg.hostname}";
 
+      package = cfg.package;
+
       listenAddress = "127.0.0.1";
       port = 9090;
 
@@ -131,14 +139,14 @@ in {
           honor_labels = false;
           scheme = if cfg.private-network then "http" else "https";
           metrics_path = "/metrics/${type}";
-          dns_sd_configs = if (hasAttr type cfg.service-discovery-dns) then [{
-            names = cfg.service-discovery-dns.${type};
-          }] else
-            [ ];
           static_configs = if (hasAttr type cfg.static-targets) then [{
             targets = cfg.static-targets.${type};
           }] else
             [ ];
+          dns_sd_configs = if (hasAttr type cfg.service-discovery-dns) then [{
+            names = cfg.service-discovery-dns.${type};
+          }] else
+            [ ];
         };
       in map make-job [ "docker" "node" "dovecot" "postfix" "rspamd" ];
 
diff --git a/lib/fudo/system.nix b/lib/fudo/system.nix
index e1a037e..c371460 100644
--- a/lib/fudo/system.nix
+++ b/lib/fudo/system.nix
@@ -431,12 +431,12 @@ in {
         SecureBits = mkIf ((length opts.requiredCapabilities) > 0) "keep-caps";
 
         DynamicUser = mkIf (opts.user == null) opts.dynamicUser;
+
         Restart = opts.restartWhen;
         WorkingDirectory =
           mkIf (opts.workingDirectory != null) opts.workingDirectory;
-        RestrictAddressFamilies =
-          optionals (opts.addressFamilies != null)
-            (restrict-address-families opts.addressFamilies);
+        RestrictAddressFamilies = optionals (opts.addressFamilies != null)
+          (restrict-address-families opts.addressFamilies);
         RestrictNamespaces = opts.restrictNamespaces;
         User = mkIf (opts.user != null) opts.user;
         Group = mkIf (opts.group != null) opts.group;
diff --git a/lib/types/host.nix b/lib/types/host.nix
index fb3cfef..7a84dea 100644
--- a/lib/types/host.nix
+++ b/lib/types/host.nix
@@ -1,350 +1,360 @@
 { lib, ... }:
 
 with lib;
-let
-  passwd = import ../passwd.nix { inherit lib; };
+let passwd = import ../passwd.nix { inherit lib; };
 
 in rec {
-  encryptedFSOpts = { ... }: let
-    mountpoint = { mp, ... }: {
+  encryptedFSOpts = { ... }:
+    let
+      mountpoint = { mp, ... }: {
+        options = with types; {
+          mountpoint = mkOption {
+            type = str;
+            description = "Path at which to mount the filesystem.";
+            default = mp;
+          };
+
+          options = mkOption {
+            type = listOf str;
+            description =
+              "List of filesystem options specific to this mountpoint (eg: subvol).";
+          };
+
+          group = mkOption {
+            type = nullOr str;
+            description = "Group to which the mountpoint should belong.";
+            default = null;
+          };
+
+          users = mkOption {
+            type = listOf str;
+            description = ''
+              List of users who should have access to the filesystem.
+
+              Requires a group to be set.
+            '';
+            default = [ ];
+          };
+
+          world-readable = mkOption {
+            type = bool;
+            description = "Whether to leave the top level world-readable.";
+            default = true;
+          };
+        };
+      };
+    in {
       options = with types; {
-        mountpoint = mkOption {
+        encrypted-device = mkOption {
           type = str;
-          description = "Path at which to mount the filesystem.";
-          default = mp;
+          description = "Path to the encrypted device.";
+        };
+
+        key-path = mkOption {
+          type = str;
+          description = ''
+            Path at which to locate the key file.
+
+            The filesystem will be decrypted and mounted once available.";
+          '';
+        };
+
+        filesystem-type = mkOption {
+          type = str;
+          description = "Filesystem type of the decrypted filesystem.";
         };
 
         options = mkOption {
           type = listOf str;
-          description = "List of filesystem options specific to this mountpoint (eg: subvol).";
+          description = "List of filesystem options with which to mount.";
         };
 
-        group = mkOption {
-          type = nullOr str;
-          description = "Group to which the mountpoint should belong.";
-          default = null;
-        };
-
-        users = mkOption {
-          type = listOf str;
-          description = ''
-            List of users who should have access to the filesystem.
-
-            Requires a group to be set.
-          '';
-          default = [ ];
-        };
-
-        world-readable = mkOption {
-          type = bool;
-          description = "Whether to leave the top level world-readable.";
-          default = true;
+        mountpoints = mkOption {
+          type = attrsOf (submodule mountpoint);
+          description =
+            "A map of mountpoints for this filesystem to fs options. Multiple to support btrfs.";
+          default = { };
         };
       };
     };
-  in {
-    options = with types; {
-      encrypted-device = mkOption {
-        type = str;
-        description = "Path to the encrypted device.";
-      };
-
-      key-path = mkOption {
-        type = str;
-        description = ''
-          Path at which to locate the key file.
-
-          The filesystem will be decrypted and mounted once available.";
-        '';
-      };
-
-      filesystem-type = mkOption {
-        type = str;
-        description = "Filesystem type of the decrypted filesystem.";
-      };
-
-      options = mkOption {
-        type = listOf str;
-        description = "List of filesystem options with which to mount.";
-      };
-
-      mountpoints = mkOption {
-        type = attrsOf (submodule mountpoint);
-        description = "A map of mountpoints for this filesystem to fs options. Multiple to support btrfs.";
-        default = {};
-      };
-    };
-  };
 
   masterKeyOpts = { ... }: {
     options = with types; {
       key-path = mkOption {
         type = str;
-        description = "Path of the host master key file, used to decrypt secrets.";
+        description =
+          "Path of the host master key file, used to decrypt secrets.";
       };
 
       public-key = mkOption {
         type = str;
-        description = "Public key used during deployment to decrypt secrets for the host.";
+        description =
+          "Public key used during deployment to decrypt secrets for the host.";
       };
     };
   };
 
-  hostOpts = { name, ... }: let
-    hostname = name;
-  in {
-    options = with types; {
-      master-key = mkOption {
-        type = nullOr (submodule masterKeyOpts);
-        description = "Public key for the host master key, used by the host to decrypt secrets.";
-      };
-
-      domain = mkOption {
-        type = str;
-        description =
-          "Primary domain to which the host belongs, in the form of a domain name.";
-        default = "fudo.org";
-      };
-
-      extra-domains = mkOption {
-        type = listOf str;
-        description = "Extra domain in which this host is reachable.";
-        default = [ ];
-      };
-
-      aliases = mkOption {
-        type = listOf str;
-        description =
-          "Host aliases used by the current host. Note this will be multiplied with extra-domains.";
-        default = [ ];
-      };
-
-      site = mkOption {
-        type = str;
-        description = "Site at which the host is located.";
-        default = "unsited";
-      };
-
-      local-networks = mkOption {
-        type = listOf str;
-        description =
-          "A list of networks to be considered trusted by this host.";
-        default = [ "127.0.0.0/8" ];
-      };
-
-      profile = mkOption {
-        type = listOf (enum ["desktop" "server" "laptop"]);
-        description =
-          "The profile to be applied to the host, determining what software is included.";
-      };
-
-      admin-email = mkOption {
-        type = nullOr str;
-        description = "Email for the administrator of this host.";
-        default = null;
-      };
-
-      local-users = mkOption {
-        type = listOf str;
-        description =
-          "List of users who should have local (i.e. login) access to the host.";
-        default = [ ];
-      };
-
-      description = mkOption {
-        type = str;
-        description = "Description of this host.";
-        default = "Another Fudo Host.";
-      };
-
-      local-admins = mkOption {
-        type = listOf str;
-        description =
-          "A list of users who should have admin access to this host.";
-        default = [ ];
-      };
-
-      local-groups = mkOption {
-        type = listOf str;
-        description = "List of groups which should exist on this host.";
-        default = [ ];
-      };
-
-      ssh-fingerprints = mkOption {
-        type = listOf str;
-        description = ''
-          A list of DNS SSHFP records for this host. Get with `ssh-keygen -r <hostname>`
-        '';
-        default = [ ];
-      };
-
-      rp = mkOption {
-        type = nullOr str;
-        description = "Responsible person.";
-        default = null;
-      };
-
-      tmp-on-tmpfs = mkOption {
-        type = bool;
-        description =
-          "Use tmpfs for /tmp. Great if you've got enough (>16G) RAM.";
-        default = true;
-      };
-
-      enable-gui = mkEnableOption "Install desktop GUI software.";
-
-      docker-server = mkEnableOption "Enable Docker on the current host.";
-
-      kerberos-services = mkOption {
-        type = listOf str;
-        description =
-          "List of services which should exist for this host, if it belongs to a realm.";
-        default = [ "ssh" "host" ];
-      };
-
-      ssh-pubkeys = mkOption {
-        type = listOf path;
-        description =
-          "SSH key files of the host.";
-        default = [];
-      };
-
-      build-pubkeys = mkOption {
-        type = listOf str;
-        description = "SSH public keys used to access the build server.";
-        default = [ ];
-      };
-
-      external-interfaces = mkOption {
-        type = listOf str;
-        description = "A list of interfaces on which to enable the firewall.";
-        default = [ ];
-      };
-
-      keytab-secret-file = mkOption {
-        type = nullOr str;
-        description = "Keytab from which to create a keytab secret.";
-        default = null;
-      };
-
-      keep-cool = mkOption {
-        type = bool;
-        description = "A host that tends to overheat. Try to keep it cooler.";
-        default = false;
-      };
-
-      nixos-system = mkOption {
-        type = bool;
-        description = "Whether the host is a NixOS system.";
-        default = true;
-      };
-
-      arch = mkOption {
-        type = str;
-        description = "System architecture of the system.";
-      };
-
-      machine-id = mkOption {
-        type = nullOr str;
-        description = "Machine id of the system. See: man machine-id.";
-        default = null;
-      };
-
-      android-dev = mkEnableOption "Enable ADB on the host.";
-
-      encrypted-filesystems = mkOption {
-        type = attrsOf (submodule encryptedFSOpts);
-        description = "List of encrypted filesystems to mount on the local host when the key is available.";
-        default = { };
-      };
-
-      hardened = mkOption {
-        type = bool;
-        description = "Harden the host, applying additional security.";
-        default = false;
-      };
-
-      wireguard = let
-        clientOpts = {
-          options = {
-            ip = mkOption {
-              type = nullOr str;
-              description = "IP address assigned to this host in the WireGuard network.";
-            };
-
-            bound = mkOption {
-              type = bool;
-              description = "Whether to route all traffic from this host.";
-              default = false;
-            };
-          };
+  hostOpts = { name, ... }:
+    let hostname = name;
+    in {
+      options = with types; {
+        master-key = mkOption {
+          type = nullOr (submodule masterKeyOpts);
+          description =
+            "Public key for the host master key, used by the host to decrypt secrets.";
         };
 
-        wireguardOpts = {
-          options = {
-            private-key-file = mkOption {
-              type = str;
-              description = "WireGuard private key file of the host.";
-            };
-
-            public-key = mkOption {
-              type = str;
-              description = "WireGuard public key.";
-            };
-
-            client = mkOption {
-              type = nullOr (submodule clientOpts);
-              default = null;
-            };
-          };
-        };
-      in mkOption {
-        type = nullOr (submodule wireguardOpts);
-        default = null;
-      };
-
-      initrd-network = let
-        keypair-type = { ... }: {
-          options = {
-            public-key = mkOption {
-              type = str;
-              description = "SSH public key.";
-            };
-
-            private-key-file = mkOption {
-              type = str;
-              description = "Path to SSH private key (on the local host!).";
-            };
-          };
+        domain = mkOption {
+          type = str;
+          description =
+            "Primary domain to which the host belongs, in the form of a domain name.";
+          default = "fudo.org";
         };
 
-        initrd-network-config = { ... }: {
-          options = {
-            ip = mkOption {
-              type = str;
-              description = "IP to assign to the initrd image, allowing access to host during bootup.";
-            };
-            keypair = mkOption {
-              type = (submodule keypair-type);
-              description = "SSH host key pair to use for initrd.";
-            };
-            interface = mkOption {
-              type = str;
-              description = "Name of interface on which to listen for connections.";
-            };
-          };
+        extra-domains = mkOption {
+          type = listOf str;
+          description = "Extra domain in which this host is reachable.";
+          default = [ ];
         };
 
-      in mkOption {
-        type = nullOr (submodule initrd-network-config);
-        description = "Configuration parameters to set up initrd SSH network.";
-        default = null;
-      };
+        aliases = mkOption {
+          type = listOf str;
+          description =
+            "Host aliases used by the current host. Note this will be multiplied with extra-domains.";
+          default = [ ];
+        };
 
-      backplane-password-file = mkOption {
-        options = path;
-        description = "File containing the password used by this host to connect to the backplane.";
+        site = mkOption {
+          type = str;
+          description = "Site at which the host is located.";
+          default = "unsited";
+        };
+
+        local-networks = mkOption {
+          type = listOf str;
+          description =
+            "A list of networks to be considered trusted by this host.";
+          default = [ "127.0.0.0/8" ];
+        };
+
+        profile = mkOption {
+          type = listOf (enum [ "desktop" "server" "laptop" ]);
+          description =
+            "The profile to be applied to the host, determining what software is included.";
+        };
+
+        admin-email = mkOption {
+          type = nullOr str;
+          description = "Email for the administrator of this host.";
+          default = null;
+        };
+
+        local-users = mkOption {
+          type = listOf str;
+          description =
+            "List of users who should have local (i.e. login) access to the host.";
+          default = [ ];
+        };
+
+        description = mkOption {
+          type = str;
+          description = "Description of this host.";
+          default = "Another Fudo Host.";
+        };
+
+        local-admins = mkOption {
+          type = listOf str;
+          description =
+            "A list of users who should have admin access to this host.";
+          default = [ ];
+        };
+
+        local-groups = mkOption {
+          type = listOf str;
+          description = "List of groups which should exist on this host.";
+          default = [ ];
+        };
+
+        ssh-fingerprints = mkOption {
+          type = listOf str;
+          description = ''
+            A list of DNS SSHFP records for this host. Get with `ssh-keygen -r <hostname>`
+          '';
+          default = [ ];
+        };
+
+        rp = mkOption {
+          type = nullOr str;
+          description = "Responsible person.";
+          default = null;
+        };
+
+        tmp-on-tmpfs = mkOption {
+          type = bool;
+          description =
+            "Use tmpfs for /tmp. Great if you've got enough (>16G) RAM.";
+          default = true;
+        };
+
+        enable-gui = mkEnableOption "Install desktop GUI software.";
+
+        docker-server = mkEnableOption "Enable Docker on the current host.";
+
+        kerberos-services = mkOption {
+          type = listOf str;
+          description =
+            "List of services which should exist for this host, if it belongs to a realm.";
+          default = [ "ssh" "host" ];
+        };
+
+        ssh-pubkeys = mkOption {
+          type = listOf path;
+          description = "SSH key files of the host.";
+          default = [ ];
+        };
+
+        build-pubkeys = mkOption {
+          type = listOf str;
+          description = "SSH public keys used to access the build server.";
+          default = [ ];
+        };
+
+        external-interfaces = mkOption {
+          type = listOf str;
+          description = "A list of interfaces on which to enable the firewall.";
+          default = [ ];
+        };
+
+        keytab-secret-file = mkOption {
+          type = nullOr str;
+          description = "Keytab from which to create a keytab secret.";
+          default = null;
+        };
+
+        keep-cool = mkOption {
+          type = bool;
+          description = "A host that tends to overheat. Try to keep it cooler.";
+          default = false;
+        };
+
+        nixos-system = mkOption {
+          type = bool;
+          description = "Whether the host is a NixOS system.";
+          default = true;
+        };
+
+        arch = mkOption {
+          type = str;
+          description = "System architecture of the system.";
+        };
+
+        machine-id = mkOption {
+          type = nullOr str;
+          description = "Machine id of the system. See: man machine-id.";
+          default = null;
+        };
+
+        android-dev = mkEnableOption "Enable ADB on the host.";
+
+        encrypted-filesystems = mkOption {
+          type = attrsOf (submodule encryptedFSOpts);
+          description =
+            "List of encrypted filesystems to mount on the local host when the key is available.";
+          default = { };
+        };
+
+        hardened = mkOption {
+          type = bool;
+          description = "Harden the host, applying additional security.";
+          default = false;
+        };
+
+        wireguard = let
+          clientOpts = {
+            options = {
+              ip = mkOption {
+                type = nullOr str;
+                description =
+                  "IP address assigned to this host in the WireGuard network.";
+              };
+
+              bound = mkOption {
+                type = bool;
+                description = "Whether to route all traffic from this host.";
+                default = false;
+              };
+            };
+          };
+
+          wireguardOpts = {
+            options = {
+              private-key-file = mkOption {
+                type = str;
+                description = "WireGuard private key file of the host.";
+              };
+
+              public-key = mkOption {
+                type = str;
+                description = "WireGuard public key.";
+              };
+
+              client = mkOption {
+                type = nullOr (submodule clientOpts);
+                default = null;
+              };
+            };
+          };
+        in mkOption {
+          type = nullOr (submodule wireguardOpts);
+          default = null;
+        };
+
+        initrd-network = let
+          keypair-type = { ... }: {
+            options = {
+              public-key = mkOption {
+                type = str;
+                description = "SSH public key.";
+              };
+
+              private-key-file = mkOption {
+                type = str;
+                description = "Path to SSH private key (on the local host!).";
+              };
+            };
+          };
+
+          initrd-network-config = { ... }: {
+            options = {
+              ip = mkOption {
+                type = str;
+                description =
+                  "IP to assign to the initrd image, allowing access to host during bootup.";
+              };
+              keypair = mkOption {
+                type = (submodule keypair-type);
+                description = "SSH host key pair to use for initrd.";
+              };
+              interface = mkOption {
+                type = str;
+                description =
+                  "Name of interface on which to listen for connections.";
+              };
+            };
+          };
+
+        in mkOption {
+          type = nullOr (submodule initrd-network-config);
+          description =
+            "Configuration parameters to set up initrd SSH network.";
+          default = null;
+        };
+
+        backplane-password-file = mkOption {
+          type = path;
+          description =
+            "File containing the password used by this host to connect to the backplane.";
+        };
       };
     };
-  };
 }