feat(ssh): add enable option

modules/ssh/authorized-keys.nix

@@ -16,16 +16,17 @@ in
     };
   };
 
-  # auto generate authorized_keys from `authorizedHosts`
-  config.users.users.${username}.openssh.authorizedKeys.keys =
-    lib.flatten (
-      map (
-        hostname:
-        let
-          keyFile = ../../hosts/${hostname}/ssh_user.pub;
-        in
-        lib.optionals (builtins.pathExists keyFile) (lib.splitString "\n" (builtins.readFile keyFile))
-      ) ((builtins.filter (h: h != config.host.name) adminHosts) ++ config.ssh.authorizedHosts)
-    )
-    ++ lib.splitString "\n" (builtins.readFile ./ssh_bak.pub);
+  config = lib.mkIf config.ssh.enable {
+    users.users.${username}.openssh.authorizedKeys.keys =
+      lib.flatten (
+        map (
+          hostname:
+          let
+            keyFile = ../../hosts/${hostname}/ssh_user.pub;
+          in
+          lib.optionals (builtins.pathExists keyFile) (lib.splitString "\n" (builtins.readFile keyFile))
+        ) ((builtins.filter (h: h != config.host.name) adminHosts) ++ config.ssh.authorizedHosts)
+      )
+      ++ lib.splitString "\n" (builtins.readFile ./ssh_bak.pub);
+  };
 }

modules/ssh/default.nix

@@ -1,10 +1,17 @@
-{ lib, ... }:
+{ lib, config, ... }:
 
+let
+  cfg = config.ssh;
+in
 {
   imports = [ ./hardened-openssh.nix ];
 
-  config.services.openssh = {
-    enable = lib.mkDefault true;
-    harden = lib.mkDefault true;
+  options.ssh.enable = lib.mkEnableOption "SSH server";
+
+  config = lib.mkIf cfg.enable {
+    services.openssh = {
+      enable = lib.mkDefault true;
+      harden = lib.mkDefault true;
+    };
   };
 }

modules/ssh/extract-keys.nix

@@ -1,32 +1,34 @@
 { lib, config, ... }:
+
 let
   inherit (config.host) username;
 in
 {
-  # auto extract SSH keys
-  system.activationScripts.extractSshKeys = lib.stringAfter [ "etc" ] ''
-    HOST_KEY="/etc/ssh/ssh_host_ed25519_key.pub"
-    HOST_DIR="/home/${username}/nix/hosts/${config.networking.hostName}"
+  config = lib.mkIf config.ssh.enable {
+    system.activationScripts.extractSshKeys = lib.stringAfter [ "etc" ] ''
+      HOST_KEY="/etc/ssh/ssh_host_ed25519_key.pub"
+      HOST_DIR="/home/${username}/nix/hosts/${config.networking.hostName}"
 
-    if [ -f "$HOST_KEY" ] && [ -d "$HOST_DIR" ]; then
-      cp "$HOST_KEY" "$HOST_DIR/ssh_host.pub"
-      chown ${username}:users "$HOST_DIR/ssh_host.pub"
-      chmod 644 "$HOST_DIR/ssh_host.pub"
-    fi
-
-    USER_KEY=""
-    for candidate in \
-        "/home/${username}/.ssh/id_ed25519_sk.pub" \
-        "/home/${username}/.ssh/id_ed25519.pub"; do
-      if [ -f "$candidate" ]; then
-        USER_KEY="$candidate"
-        break
+      if [ -f "$HOST_KEY" ] && [ -d "$HOST_DIR" ]; then
+        cp "$HOST_KEY" "$HOST_DIR/ssh_host.pub"
+        chown ${username}:users "$HOST_DIR/ssh_host.pub"
+        chmod 644 "$HOST_DIR/ssh_host.pub"
       fi
-    done
-    if [ -n "$USER_KEY" ] && [ -d "$HOST_DIR" ]; then
-      cp "$USER_KEY" "$HOST_DIR/ssh_user.pub"
-      chown ${username}:users "$HOST_DIR/ssh_user.pub"
-      chmod 644 "$HOST_DIR/ssh_user.pub"
-    fi
-  '';
+
+      USER_KEY=""
+      for candidate in \
+          "/home/${username}/.ssh/id_ed25519_sk.pub" \
+          "/home/${username}/.ssh/id_ed25519.pub"; do
+        if [ -f "$candidate" ]; then
+          USER_KEY="$candidate"
+          break
+        fi
+      done
+      if [ -n "$USER_KEY" ] && [ -d "$HOST_DIR" ]; then
+        cp "$USER_KEY" "$HOST_DIR/ssh_user.pub"
+        chown ${username}:users "$HOST_DIR/ssh_user.pub"
+        chmod 644 "$HOST_DIR/ssh_user.pub"
+      fi
+    '';
+  };
 }

modules/ssh/hardened-openssh.nix

@@ -1,5 +1,7 @@
 { lib, config, ... }:
+
 with lib;
+
 let
   cfg = config.services.openssh;
 in
@@ -13,7 +15,7 @@ in
   options.services.openssh.harden = mkEnableOption "harden ssh server configuration";
 
   config = {
-    networking.firewall.allowedTCPPorts = [ 22 ];
+    networking.firewall.allowedTCPPorts = lib.mkIf config.ssh.enable [ 22 ];
 
     services.openssh.settings = optionalAttrs cfg.harden {
       PermitRootLogin = "no";

modules/ssh/known-hosts.nix

@@ -4,6 +4,7 @@
   outputs,
   ...
 }:
+
 let
   hosts = lib.attrNames outputs.nixosConfigurations;
   hostsWithKeys = lib.filter (
@@ -11,9 +12,10 @@ let
   ) hosts;
 in
 {
-  # auto generate known_hosts for all hosts in flake
-  programs.ssh.knownHosts = lib.genAttrs hostsWithKeys (hostname: {
-    publicKeyFile = ../../hosts/${hostname}/ssh_host.pub;
-    extraHostNames = lib.optional (hostname == config.networking.hostName) "localhost";
-  });
+  config = lib.mkIf config.ssh.enable {
+    programs.ssh.knownHosts = lib.genAttrs hostsWithKeys (hostname: {
+      publicKeyFile = ../../hosts/${hostname}/ssh_host.pub;
+      extraHostNames = lib.optional (hostname == config.networking.hostName) "localhost";
+    });
+  };
 }