WIP: add generator modules

flake.nix

@@ -16,6 +16,7 @@
     in {
       nixosModules.default = { imports = [ ./options.nix ]; };
       nixosModules.backend-on-machine = { imports = [ ./backends/on-machine.nix ]; };
+      nixosModules.generators = { imports = [ ./generators ]; };
       # TODO fix tests
       checks = forAllSystems (system: let
         tests = {

generators/default.nix

@@ -0,0 +1,11 @@
+{
+  imports = [
+    ./disk-id
+    ./garage
+    ./machine-id
+    ./root-password
+    ./sshd
+    ./state-version
+    ./user-password
+  ];
+}

generators/disk-id/default.nix

@@ -0,0 +1,30 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  cfg = config.vars.disk-id;
+in
+{
+  options.vars.disk-id.enable = lib.mkEnableOption "Generates a uuid for use in disk device naming";
+  config = lib.mkIf cfg.enable {
+    vars.generators.disk-id = {
+      files.diskId.secret = false;
+      runtimeInputs = [
+        pkgs.coreutils
+        pkgs.bash
+      ];
+      script = ''
+        uuid=$(bash ${./uuid4.sh})
+
+        # Remove the hyphens from the UUID
+        uuid_no_hyphens=$(echo -n "$uuid" | tr -d '-')
+
+        echo -n "$uuid_no_hyphens" > "$out/diskId"
+      '';
+    };
+    disko.devices.disk."main".name = "main-" + config.vars.generators.disk-id.files.diskId.value;
+  };
+}

generators/disk-id/uuid4.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+# Read 16 bytes from /dev/urandom
+uuid=$(dd if=/dev/urandom bs=1 count=16 2>/dev/null | od -An -tx1 | tr -d ' \n')
+
+# Break the UUID into pieces and apply the required modifications
+byte6=${uuid:12:2}
+byte8=${uuid:16:2}
+
+# Construct the correct version and variant
+hex_byte6=$(printf "%x" $((0x$byte6 & 0x0F | 0x40)))
+hex_byte8=$(printf "%x" $((0x$byte8 & 0x3F | 0x80)))
+
+# Rebuild the UUID with the correct fields
+uuid_v4="${uuid:0:12}${hex_byte6}${uuid:14:2}${hex_byte8}${uuid:18:14}"
+
+# Format the UUID correctly 8-4-4-4-12
+uuid_formatted="${uuid_v4:0:8}-${uuid_v4:8:4}-${uuid_v4:12:4}-${uuid_v4:16:4}-${uuid_v4:20:12}"
+
+echo -n "$uuid_formatted"

generators/garage/default.nix

@@ -0,0 +1,59 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  cfg = config.vars.garage;
+in
+{
+  options.vars.garage.enable = lib.mkEnableOption ''
+    S3-compatible object store for small self-hosted geo-distributed deployments.
+
+    This module generates garage-specific keys automatically.
+
+    Options: [NixosModuleOptions](https://search.nixos.org/options?channel=unstable&size=50&sort=relevance&type=packages&query=garage)
+    Documentation: https://garagehq.deuxfleurs.fr/
+  '';
+  config = lib.mkIf cfg.enable {
+    systemd.services.garage.serviceConfig = {
+      LoadCredential = [
+        "rpc_secret_path:${config.vars.generators.garage-shared.files.rpc_secret.path}"
+        "admin_token_path:${config.vars.generators.garage.files.admin_token.path}"
+        "metrics_token_path:${config.vars.generators.garage.files.metrics_token.path}"
+      ];
+      Environment = [
+        "GARAGE_ALLOW_WORLD_READABLE_SECRETS=true"
+        "GARAGE_RPC_SECRET_FILE=%d/rpc_secret_path"
+        "GARAGE_ADMIN_TOKEN_FILE=%d/admin_token_path"
+        "GARAGE_METRICS_TOKEN_FILE=%d/metrics_token_path"
+      ];
+    };
+
+    vars.generators.garage = {
+      files.admin_token = { };
+      files.metrics_token = { };
+      runtimeInputs = [
+        pkgs.coreutils
+        pkgs.openssl
+      ];
+      script = ''
+        openssl rand -base64 -out "$out"/admin_token 32
+        openssl rand -base64 -out "$out"/metrics_token 32
+      '';
+    };
+
+    vars.generators.garage-shared = {
+      share = true;
+      files.rpc_secret = { };
+      runtimeInputs = [
+        pkgs.coreutils
+        pkgs.openssl
+      ];
+      script = ''
+        openssl rand -hex -out "$out"/rpc_secret 32
+      '';
+    };
+  };
+}

generators/machine-id/default.nix

@@ -0,0 +1,46 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  var = config.vars.generators.machine-id.files.machineId or { };
+  cfg = config.vars.machine-id;
+in
+{
+  options.vars.machine-id.enable = lib.mkEnableOption "Sets the /etc/machine-id and exposes it as a nix option";
+  config = lib.mkIf cfg.enable (lib.mkMerge [
+    (lib.mkIf ((var.value or null) != null) {
+      assertions = [
+        {
+          assertion = lib.stringLength var.value == 32;
+          message = "machineId must be exactly 32 characters long.";
+        }
+      ];
+      boot.kernelParams = [
+        ''systemd.machine_id=${var.value}''
+      ];
+      environment.etc."machine-id" = {
+        text = var.value;
+      };
+    })
+    {
+      vars.generators.machine-id = {
+        files.machineId.secret = false;
+        runtimeInputs = [
+          pkgs.coreutils
+          pkgs.bash
+        ];
+        script = ''
+          uuid=$(bash ${./uuid4.sh})
+
+          # Remove the hyphens from the UUID
+          uuid_no_hyphens=$(echo -n "$uuid" | tr -d '-')
+
+          echo -n "$uuid_no_hyphens" > "$out/machineId"
+        '';
+      };
+    }
+  ]);
+}

generators/machine-id/uuid4.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+# Read 16 bytes from /dev/urandom
+uuid=$(dd if=/dev/urandom bs=1 count=16 2>/dev/null | od -An -tx1 | tr -d ' \n')
+
+# Break the UUID into pieces and apply the required modifications
+byte6=${uuid:12:2}
+byte8=${uuid:16:2}
+
+# Construct the correct version and variant
+hex_byte6=$(printf "%x" $((0x$byte6 & 0x0F | 0x40)))
+hex_byte8=$(printf "%x" $((0x$byte8 & 0x3F | 0x80)))
+
+# Rebuild the UUID with the correct fields
+uuid_v4="${uuid:0:12}${hex_byte6}${uuid:14:2}${hex_byte8}${uuid:18:14}"
+
+# Format the UUID correctly 8-4-4-4-12
+uuid_formatted="${uuid_v4:0:8}-${uuid_v4:8:4}-${uuid_v4:12:4}-${uuid_v4:16:4}-${uuid_v4:20:12}"
+
+echo -n "$uuid_formatted"

generators/options.nix

@@ -0,0 +1,9 @@
+{
+  lib,
+  ...
+}:
+{
+  options.vars = {
+    unattended = lib.mkEnableOption "Whether to default to generating values unattended, rather than prompting for desired values.";
+  };
+}

generators/root-password/default.nix

@@ -0,0 +1,60 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  cfg = config.vars.root-password;
+in
+{
+  imports = [
+    ../options.nix
+  ];
+  options.vars.root-password = {
+    enable = lib.mkEnableOption "Automatically generates and configures a password for the root user.";
+    prompt = lib.mkOption {
+      type = lib.types.bool;
+      default = !config.vars.unattended;
+      example = true;
+      description = "Whether the user should be prompted.";
+    };
+  };
+  config = lib.mkIf cfg.enable {
+    users.mutableUsers = false;
+    users.users.root.hashedPasswordFile =
+      config.vars.generators.root-password.files.password-hash.path;
+
+    vars.generators.root-password = {
+      files.password-hash = {
+        neededFor = "users";
+      };
+      files.password-hash.restartUnits = lib.optional (config.services.userborn.enable) "userborn.service";
+      files.password = {
+        deploy = false;
+      };
+      runtimeInputs = [
+        pkgs.coreutils
+        pkgs.mkpasswd
+        pkgs.xkcdpass
+      ];
+      prompts = lib.mkIf cfg.prompt {
+        password = {
+          type = "hidden";
+          persist = true;
+          description = "You can autogenerate a password, if you leave this prompt blank.";
+        };
+      };
+
+      script = ''
+        prompt_value=${if cfg.prompt then ''$(cat "$prompts"/password)'' else ""}
+        if [[ -n "''${prompt_value-}" ]]; then
+          echo "$prompt_value" | tr -d "\n" > "$out"/password
+        else
+          xkcdpass --numwords 3 --delimiter - --count 1 | tr -d "\n" > "$out"/password
+        fi
+        mkpasswd -s -m sha-512 < "$out"/password | tr -d "\n" > "$out"/password-hash
+      '';
+    };
+  };
+}

generators/sshd/client.nix

@@ -0,0 +1,6 @@
+{ ... }:
+{
+  imports = [
+    ./shared.nix
+  ];
+}

generators/sshd/default.nix

@@ -0,0 +1,6 @@
+{
+  imports = [
+    ./client.nix
+    ./server.nix
+  ];
+}

generators/sshd/server.nix

@@ -0,0 +1,103 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+let
+  stringSet = list: builtins.attrNames (builtins.groupBy lib.id list);
+
+  domains = stringSet config.vars.sshd.certificate.searchDomains;
+
+  cfg = config.vars.sshd;
+
+  name = config.networking.hostName;
+in
+{
+  imports = [ ../shared.nix ];
+  options = {
+    vars.sshd = {
+      enable = lib.mkEnableOption "Set up the opensshd service, generating a host key for the machine.";
+      hostKeys.rsa.enable = lib.mkEnableOption "Generate RSA host key";
+    };
+  };
+  config = lib.mkIf cfg.enable {
+    services.openssh = {
+      enable = true;
+      settings.PasswordAuthentication = false;
+
+      settings.HostCertificate = lib.mkIf (
+        cfg.certificate.searchDomains != [ ]
+      ) config.vars.generators.openssh-cert.files."ssh.id_ed25519-cert.pub".path;
+
+      hostKeys =
+        [
+          {
+            path = config.vars.generators.openssh.files."ssh.id_ed25519".path;
+            type = "ed25519";
+          }
+        ]
+        ++ lib.optional cfg.hostKeys.rsa.enable {
+          path = config.vars.generators.openssh-rsa.files."ssh.id_rsa".path;
+          type = "rsa";
+        };
+    };
+
+    vars.generators.openssh = {
+      files."ssh.id_ed25519" = { };
+      files."ssh.id_ed25519.pub".secret = false;
+      runtimeInputs = [
+        pkgs.coreutils
+        pkgs.openssh
+      ];
+      script = ''
+        ssh-keygen -t ed25519 -N "" -f "$out"/ssh.id_ed25519
+      '';
+    };
+
+    programs.ssh.knownHosts.sshd-self-ed25519 = {
+      hostNames = [
+        "localhost"
+        config.networking.hostName
+      ] ++ (lib.optional (config.networking.domain != null) config.networking.fqdn);
+      publicKey = config.vars.generators.openssh.files."ssh.id_ed25519.pub".value;
+    };
+
+    vars.generators.openssh-rsa = lib.mkIf config.vars.sshd.hostKeys.rsa.enable {
+      files."ssh.id_rsa" = { };
+      files."ssh.id_rsa.pub".secret = false;
+      runtimeInputs = [
+        pkgs.coreutils
+        pkgs.openssh
+      ];
+      script = ''
+        ssh-keygen -t rsa -b 4096 -N "" -f "$out"/ssh.id_rsa
+      '';
+    };
+
+    vars.generators.openssh-cert = lib.mkIf (cfg.certificate.searchDomains != [ ]) {
+      files."ssh.id_ed25519-cert.pub".secret = false;
+      dependencies = [
+        "openssh"
+        "openssh-ca"
+      ];
+      validation = {
+        inherit name;
+        domains = lib.genAttrs config.vars.sshd.certificate.searchDomains lib.id;
+      };
+      runtimeInputs = [
+        pkgs.openssh
+        pkgs.jq
+      ];
+      script = ''
+        ssh-keygen \
+          -s $in/openssh-ca/id_ed25519 \
+          -I ${name} \
+          -h \
+          -n ${lib.concatMapStringsSep "," (d: "${name}.${d}") domains} \
+          $in/openssh/ssh.id_ed25519.pub
+        mv $in/openssh/ssh.id_ed25519-cert.pub "$out"/ssh.id_ed25519-cert.pub
+      '';
+    };
+  };
+}