breaking up mtls with better wrappers

2026-07-05 22:59:05 -05:00
parent 39504cd856
commit 1b98c83d3f
4 changed files with 302 additions and 514 deletions
@@ -0,0 +1,167 @@
+{ self, inputs, lib, ... }:
+let
+  # Options that will be in common between the nixos module and the home-manager module.
+  mkOpts = config: let cfg = config.mtls; in {
+    enable = lib.mkEnableOption "Enable mTLS";
+    subject = lib.mkOption {
+      description = "The Common Name, DNS Name, or IP address that will be set as the Subject Common Name for the certificate. If no Subject Alternative Names (SANs) are configured (via the --san flag) then the subject will be set as the only SAN.";
+      type = lib.types.str;
+    };
+    certDir = lib.mkOption {
+      description = "String path to the directory where the certs will be stored";
+      type = lib.types.str;
+    };
+    caFile = lib.mkOption {
+      description = "String path for the root CA file";
+      type = lib.types.str;
+      default = "${cfg.certDir}/root_ca.crt";
+    };
+    keyFile = lib.mkOption {
+      description = "String path for the private key";
+      type = lib.types.str;
+      default = "${cfg.certDir}/key.pem";
+    };
+    certFile = lib.mkOption {
+      description = "String path for the public cert";
+      type = lib.types.str;
+      default = "${cfg.certDir}/cert.pem";
+    };
+    bundleFile = lib.mkOption {
+      description = "String path for the mTLS key bundle";
+      type = lib.types.str;
+      default = "${cfg.certDir}/mtls.pem";
+    };
+    san = lib.mkOption {
+      description = "List of SAN to give the mTLS cert";
+      type = lib.types.listOf lib.types.str;
+      default = [ ];
+    };
+    provisioner = lib.mkOption {
+      type = lib.types.str;
+      default = "admin";
+    };
+    lifetime = lib.mkOption {
+      type = lib.types.str;
+      default = "24h";
+    };
+    renew = {
+      enable = lib.mkOption {
+        description = "Enable automatic mTLS certificate renewal using a systemd timer.";
+        type = lib.types.bool;
+        default = cfg.enable;
+      };
+      onCalendar = lib.mkOption {
+        description = "systemd OnCalendar schedule for mTLS certificate renewal checks.";
+        type = lib.types.str;
+        default = "*:1/15";
+      };
+      randomizedDelaySec = lib.mkOption {
+        description = "Randomized delay added to renewal timer runs to avoid synchronized renewals.";
+        type = lib.types.str;
+        default = "5m";
+      };
+      user = lib.mkOption {
+        description = "User account to run the mTLS renewal service as.";
+        type = lib.types.str;
+        default = "root";
+      };
+      group = lib.mkOption {
+        description = "Group to run the mTLS renewal service as. Defaults to the configured renewal user.";
+        type = lib.types.nullOr lib.types.str;
+        default = "mtls";
+      };
+      reloadUnits = lib.mkOption {
+        description = "systemd units to try-reload-or-restart after a successful certificate renewal.";
+        type = lib.types.listOf lib.types.str;
+        default = [ ];
+      };
+      postCommands = lib.mkOption {
+        description = "Shell commands to run after a successful certificate renewal.";
+        type = lib.types.listOf lib.types.lines;
+        default = [ ];
+      };
+    };
+  };
+in
+{
+  flake.modules.nixos.mtls = { config, lib, pkgs, ... }:
+    let
+      cfg = config.mtls;
+      mtlsWrappers = inputs.self.wrappers.mtls;
+      mtlsGenerate = mtlsWrappers.generate.apply {
+        inherit pkgs;
+        inherit (cfg) subject;
+        SANs = cfg.san;
+        provisioner = "admin";
+        provisionerPasswordFile = config.sops.secrets."janus/admin_jwk".path;
+      };
+      mtlsRenew = mtlsWrappers.renew.apply {
+        inherit pkgs;
+      };
+      mtlsCheck = mtlsWrappers.check.apply {
+        inherit pkgs;
+      };
+    in
+    {
+      options.mtls = (mkOpts config) // {
+        certDir = lib.mkOption {
+          description = "String path to where the mtls certs will be stored.";
+          type = lib.types.str;
+          default = "/etc/step-ca/certs";
+        };
+        bootstrap = {
+          enable = lib.mkOption {
+            description = "Enable initial mTLS issuance when cert material is missing or invalid.";
+            type = lib.types.bool;
+            default = false;
+          };
+          wantedBy = lib.mkOption {
+            description = "systemd targets that should pull in mtls-bootstrap.service.";
+            type = with lib.types; listOf str;
+            default = [ "multi-user.target" ];
+          };
+          after = lib.mkOption {
+            description = "systemd units/targets that mtls-bootstrap.service should run after.";
+            type = with lib.types; listOf str;
+            default = [ "network-online.target" ];
+          };
+          wants = lib.mkOption {
+            description = "systemd units/targets that mtls-bootstrap.service should pull in.";
+            type = with lib.types; listOf str;
+            default = [ "network-online.target" ];
+          };
+          provisionerPasswordFile = lib.mkOption {
+            description = "Optional path passed to mtls-generate as --provisioner-password-file for noninteractive issuance.";
+            type = lib.types.nullOr lib.types.str;
+            default = null;
+          };
+        };
+        certReaders = lib.mkOption {
+          description = "";
+          type = lib.types.listOf lib.types.str;
+          default = [ ];
+        };
+      };
+
+      config = lib.mkIf cfg.enable {
+        users.groups.certReaders = {
+          name = cfg.renew.group;
+          members = cfg.certReaders;
+        };
+
+        environment.systemPackages = [
+          mtlsGenerate.wrapper
+          mtlsCheck.wrapper
+          mtlsRenew.wrapper
+        ];
+
+        systemd = {
+          packages = [ mtlsRenew.outputs.systemd-system ];
+          # Timer-driven oneshot: only the timer is enabled. NixOS does not
+          # honor the unit's [Install] section for systemd.packages, so the
+          # wantedBy must be set explicitly here.
+          timers.mtls-renew.wantedBy = [ "timers.target" ];
+        };
+      };
+    };
+}