chore(secrets): placeholder for the LDAP bind secret

.gitea/workflows/ci.yaml

@@ -54,7 +54,7 @@ jobs:
 
       - name: Install Nix
         if: steps.detect.outputs.run == 'true'
-        uses: cachix/install-nix-action@a49548c11d9846ad46ecc0115273879b045f001c # v31
+        uses: cachix/install-nix-action@8aa03977d8d733052d78f4e008a241fd1dbf36b3 # v31
         with:
           extra_nix_config: |
             experimental-features = nix-command flakes

README.md

@@ -12,67 +12,16 @@ Defined in the host table in [`flake.nix`](./flake.nix):
 | `lyrathorpe-mbp`      | `aarch64-linux`  | MacBook Pro (Apple Silicon, Asahi)                                                                          |
 | `lyrathorpe-t400`     | `x86_64-linux`   | ThinkPad T400 — [install notes](./hosts/T400/README.md)                                                     |
 | `lyrathorpe-macpro31` | `x86_64-linux`   | Mac Pro 3,1, desktop — [install notes](./hosts/MacPro31/README.md)                                          |
-| `emmathorpe-edaas`    | `x86_64-linux`   | Work WSL box (NixOS-WSL) — [notes](./hosts/EDaaS/README.md)                                                 |
+| `emmathorpe-edaas`    | `x86_64-linux`   | Work WSL box (NixOS-WSL)                                                                                    |
 | `lyrathorpe-rpi5`     | `aarch64-linux`  | Raspberry Pi 5 headless server: Docker host + nginx reverse proxy — [install notes](./hosts/RPi5/README.md) |
-| `lyrathorpe-mac`      | `aarch64-darwin` | macOS (nix-darwin) — [notes](./hosts/Darwin/README.md)                                                      |
+| `lyrathorpe-mac`      | `aarch64-darwin` | macOS (nix-darwin)                                                                                          |
 
 Shared layers: `home` (home-manager: shell, git, editor),
 `modules/common-nixos.nix` (all NixOS hosts: fonts, nix-ld, caches),
 `modules/workstation.nix` (physical graphical hosts: audio, thermald,
 earlyoom, fwupd), `modules/laptop.nix` (laptops: Wi-Fi, Bluetooth, power,
-lid), `modules/desktop.nix` (wired desktops: NetworkManager), and
+lid), and `modules/ssh.nix` (key-only sshd). The x86 hosts also pull
-`modules/ssh.nix` (key-only sshd). The x86 hosts also pull `nixos-hardware`
+`nixos-hardware` profiles.
-profiles. The full module catalogue is below.
-
-## Repository layout
-
-```
-flake.nix              # inputs, mkHost/mkDarwinHost, the host tables, dev shell + checks
-flake.lock             # pinned input revisions (Renovate keeps this fresh)
-modules/               # reusable NixOS system modules (see "Module catalogue")
-home/                  # home-manager profile: shell, git, editor, claude, desktop, sway
-users/                 # identity registry + per-user home extras (see "Users")
-hosts/<Name>/          # per-machine config: configuration.nix + hardware-configuration.nix
-lib/                   # small pure helpers (currently the Catppuccin Mocha palette)
-.gitea/workflows/      # CI (nix flake check + per-host eval)
-statix.toml            # lint config (house-style lints disabled)
-.editorconfig          # base whitespace style
-tf-inspect/            # UNRELATED scratch project (gitignored, its own git repo);
-                       #   RouterOS / home-services Terraform, not part of this flake
-```
-
-Each `nixosConfiguration` / `darwinConfiguration` is assembled in `flake.nix`
-from three layers: the shared `baseModules` (or `darwinBaseModules`), the
-per-form-factor and `nixos-hardware` modules listed in the host table, and the
-per-machine `hosts/<Name>/configuration.nix`. Home-manager is wired in as a
-system module; each user's home is composed from the `homeModules` list in that
-host's table entry.
-
-## Module catalogue
-
-Reusable NixOS modules under [`modules/`](./modules). "Imported by" says how a
-module reaches a host: **baseModules** (every NixOS host, via `flake.nix`),
-**host table** (listed explicitly per host in `flake.nix`), or **transitively**
-(pulled in by another module's `imports`).
-
-| Module               | Imported by                             | What it does / when to use it                                                                                                                                                                    |
-| -------------------- | --------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| `common-nixos.nix`   | baseModules (all NixOS)                 | Timezone/locale, store hygiene (auto-optimise, big download buffer, **no** auto-GC), the nix-community binary cache, `nix-ld`, base CLI (`git`, `fastfetch`), and the fleet-wide font stack.     |
-| `users.nix`          | baseModules (all NixOS)                 | Builds `users.users` from the registry for the host's `hostUsers`; enables zsh; enables Firefox + Thunderbird **only** when `features.swayDesktop.enable` is on. Applies per-user `linger`.       |
-| `features.nix`       | baseModules (all NixOS)                 | Declares feature-flag options (currently `features.swayDesktop.enable`) so any host can read/set them without importing the heavy implementation module.                                          |
-| `workstation.nix`    | transitively (via laptop/desktop)       | Form-factor-agnostic base for physical graphical hosts: turns on `swayDesktop`, Dvorak console, PipeWire, firewall (default-deny), fstrim, earlyoom, fwupd, thermald (x86), redistributable fw.  |
-| `laptop.nix`         | host table (MBP, T400)                  | `imports` workstation.nix, then adds the portable bits: iwd Wi-Fi, lid suspend/lock, Bluetooth + blueman.                                                                                        |
-| `desktop.nix`        | host table (Mac Pro)                    | `imports` workstation.nix, then swaps Wi-Fi for wired NetworkManager. Pair with `portable = false` in the host table.                                                                            |
-| `sway.nix`           | host table (graphical hosts)            | Implementation of `features.swayDesktop`: the system Sway package, the greetd/ReGreet (cage) greeter forced to Dvorak, xdg-portal, Wayland utility packages. Home-side Sway config is in `home/sway.nix`. |
-| `ssh.nix`            | host table (T400, Mac Pro, RPi5)        | Enables sshd, opens port 22, enforces a key-only policy (no password / keyboard-interactive, no root). Authorized keys come from the registry via `users.nix`.                                    |
-| `firmware/`          | referenced by MBP host config           | Committed Apple peripheral firmware blobs for the Asahi MBP (see "MacBook (Asahi) firmware").                                                                                                     |
-
-Form-factor decision: a **laptop** imports `laptop.nix` (default
-`portable = true`); a **wired desktop** imports `desktop.nix` and sets
-`portable = false`; a **headless server** imports neither (leaves
-`features.swayDesktop.enable` at its default `false`) and adds only what it
-serves. `portable` is threaded through to `home/sway.nix`, which drops the
-battery block and brightness keys on desktops.
 
 ## Users
 
@@ -89,16 +38,6 @@ Identity is data, kept separate from the reusable modules:
   identity into that user's home config as the `identity` module arg. A host can
   therefore declare any number of users.
 
-Per-user home extras live under `users/<name>/`:
-
-- [`users/lyrathorpe/home.nix`](./users/lyrathorpe/home.nix) — personal extras
-  (an ssh host shortcut, gammastep coordinates); imported on Lyra's hosts.
-- [`users/emmathorpe/work.nix`](./users/emmathorpe/work.nix) — the work
-  toolchain (kubectl/helm/az/etc.), work-only LSP servers, and the corporate ssh
-  handling; imports
-  [`users/emmathorpe/renovate-review.nix`](./users/emmathorpe/renovate-review.nix),
-  the daily headless Renovate-PR review timer (EDaaS only).
-
 ### Portable home (off-NixOS / external consumers)
 
 The home config is also exposed for use beyond these hosts:
@@ -113,6 +52,33 @@ The home config is also exposed for use beyond these hosts:
   (`inputs.<this>.homeModules.default`). Consumers must supply the module args
   these expect: `inputs` always, `identity` for git/desktop, `portable` for sway.
 
+## Directory authentication (SSSD → Authentik LDAP)
+
+Every NixOS host authenticates users against the Authentik LDAP outpost via
+SSSD, implemented in [`modules/sssd.nix`](./modules/sssd.nix) and enabled by
+default through the `services.authentikLdap.enable` option (added to
+`baseModules`). The **EDaaS** WSL box opts out
+(`services.authentikLdap.enable = false`) as a work-managed environment; the
+macOS host is unaffected (SSSD is Linux-only).
+
+- Connects over LDAPS to `ldap.lyrapup.pet:636`, search base
+  `dc=ldap,dc=goauthentik,dc=io`, binding as
+  `cn=sssd-bind,ou=users,dc=ldap,dc=goauthentik,dc=io`.
+- The schema mappings match Authentik's non-standard object classes
+  (`goauthentik.io/ldap/user`, `goauthentik.io/ldap/group`) over the POSIX
+  attributes (`uid`, `uidNumber`, `gidNumber`, `homeDirectory`).
+- Home directories are created on first login (`pam_mkhomedir`).
+
+### Secrets (agenix)
+
+The LDAP bind credential is an [agenix](https://github.com/ryantm/agenix)
+secret, decrypted at activation with each host's SSH host key. The decrypted
+plaintext is a full `sssd.conf` drop-in delivered to
+`/etc/sssd/conf.d/01-ldap-authtok.conf`, so the password never enters the Nix
+store. Owner setup (host recipient keys, encrypting the bind password, DNS for
+`ldap.lyrapup.pet`, rebuild) is documented in
+[`secrets/README.md`](./secrets/README.md).
+
 ## Applying
 
 ```sh
@@ -122,36 +88,6 @@ sudo nixos-rebuild switch --flake .#<configuration>
 darwin-rebuild switch --flake .#lyrathorpe-mac
 ```
 
-On a host whose `networking.hostName` matches its flake attribute (the WSL box
-and the Pi are set up this way), `nh os switch` resolves the configuration from
-the hostname with no `--flake`/`-H` flag.
-
-## Adding a new host
-
-1. **Create `hosts/<Name>/`.** Add `configuration.nix` with the host-specific
-   bits only: `networking.hostName`, bootloader (firmware-specific — it is
-   deliberately not set in the shared modules), and any per-machine hardware
-   quirks. Keep anything reusable in `modules/` instead.
-2. **Hardware config.** Generate `hardware-configuration.nix` on the real
-   machine with `nixos-generate-config` and commit it. If the machine does not
-   exist yet, commit a clearly-labelled placeholder so the host still evaluates
-   in CI (see the existing T400 / RPi5 placeholders), and replace it at install.
-   These files are excluded from the formatter and linters.
-3. **Add a host-table entry in `flake.nix`.** Under `hosts` (NixOS) or
-   `darwinHosts` (macOS), set `system`, the `modules` list (host config + form
-   factor + any `nixos-hardware` profiles), and the `users` map (each user's
-   `homeModules`). Choose the form factor per the decision note above; a headless
-   host imports neither `laptop.nix` nor `desktop.nix`.
-4. **Users.** If the host introduces a new person, add them to
-   `users/registry.nix` first; otherwise reference an existing username.
-5. **Verify.** `nix flake check` formats, lints, and evaluates every host —
-   including the new one — so a broken entry fails locally before CI. Then
-   `sudo nixos-rebuild switch --flake .#<configuration>` on the machine.
-
-No change to CI is needed: the host-eval step discovers hosts from the flake
-(`attrNames` of the configuration sets), so a new entry is picked up
-automatically.
-
 ## Shell environment & keybindings
 
 - Interactive shell features (zsh, tmux, git, ssh, CLI tools, auto-tmux):
@@ -202,7 +138,4 @@ A dev shell and a formatting/lint gate are wired through the flake:
 
 [`.gitea/workflows/ci.yaml`](./.gitea/workflows/ci.yaml) runs `nix flake check`
 (formatting, `deadnix`, `statix`, the pre-commit hooks) and evaluates every
-NixOS and Darwin host configuration on push/PR. It always runs (no `paths:`
+NixOS and Darwin host configuration on push/PR.
-filter) so the required check never hangs pending; the heavy Nix steps are
-skipped when a PR touches no `.nix`/lockfile/workflow file, and the job still
-reports green.

flake.nix

@@ -46,6 +46,15 @@
       url = "github:cachix/git-hooks.nix";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    # agenix: age-encrypted secrets, decrypted at activation with each host's
+    # SSH host key. Provides the SSSD LDAP bind credential (secrets/, see
+    # modules/sssd.nix). The darwin module is intentionally unused (SSSD is
+    # Linux-only).
+    agenix = {
+      url = "github:ryantm/agenix";
+      inputs.nixpkgs.follows = "nixpkgs";
+      inputs.home-manager.follows = "home-manager";
+    };
     # Declarative Neovim (the editor; see home/editor.nix). Release
     # branch matched to the pinned nixpkgs (26.05); follows our nixpkgs to keep a
     # single nixpkgs in the closure. editor.nix sets programs.nixvim.nixpkgs.source
@@ -123,7 +132,9 @@
           ./modules/users.nix
           ./modules/common-nixos.nix
           ./modules/features.nix
+          ./modules/sssd.nix
           commonModule
+          inputs.agenix.nixosModules.default
           home-manager.nixosModules.home-manager
           {
             home-manager.useGlobalPkgs = true;

hosts/Darwin/README.md

@@ -1,51 +0,0 @@
-# macOS (nix-darwin) — `lyrathorpe-mac`
-
-Flake host: `lyrathorpe-mac` (`aarch64-darwin`). Apple Silicon Mac managed by
-**nix-darwin** from this same flake. Built via `mkDarwinHost` (single-user —
-macOS owns the account; identity still comes from the registry). Files:
-`configuration.nix`.
-
-## What this host is
-
-A macOS workstation. The interactive user environment (shell, git, editor,
-Claude) is the **shared `../../home` bundle** — the same modules the Linux hosts
-use — so the terminal experience matches. The Linux-only `desktop.nix`/`sway.nix`
-are intentionally left out. This host config covers the macOS-specific layer:
-system packages, Homebrew, and macOS UI defaults.
-
-## Package sourcing
-
-- **nixpkgs** (`environment.systemPackages`) for CLI tooling and libraries.
-- **Homebrew**, owned declaratively by `nix-homebrew` (Rosetta enabled for
-  x86_64 formulae). The `brews`/`casks` lists are **authoritative**:
-  `onActivation.cleanup = "zap"` uninstalls anything not declared. GUI apps are
-  casks (nixpkgs darwin GUI support is unreliable); a few version-pinned
-  toolchains and the PWA host stay on brew for continuity.
-- **Mac App Store** apps are **not** declarative: nix-darwin 26.05 runs
-  activation as root, and `mas` cannot reach the App Store session from root.
-  Install them by hand with `mas install <id>` from a GUI Terminal (the `mas`
-  CLI is in `environment.systemPackages`).
-
-## macOS integration
-
-- `security.pam.services.sudo_local` — **Touch ID for sudo** (and
-  `darwin-rebuild`'s sudo prompt), kept in `sudo_local` so it survives OS
-  updates. `reattach` pulls in `pam_reattach` so Touch ID works inside tmux
-  (which the terminals auto-start).
-- `system.defaults` — declarative dock / finder / global / trackpad preferences,
-  applied on activation and reversible. This is the main reason to run nix-darwin
-  beyond package management.
-- The JetBrainsMono Nerd Font is installed to `/Library/Fonts`; set it in
-  iTerm2 (Settings → Profiles → Text → Font) so the tmux statusline glyphs
-  render.
-
-## stateVersion
-
-`system.stateVersion = 5` (the nix-darwin state version, an integer — not a
-NixOS release string). Read `darwin-rebuild changelog` before changing it.
-
-## Apply
-
-```sh
-darwin-rebuild switch --flake .#lyrathorpe-mac
-```

hosts/EDaaS/README.md

@@ -1,53 +0,0 @@
-# Work WSL box — `emmathorpe-edaas`
-
-Flake host: `emmathorpe-edaas` (`x86_64-linux`). NixOS running under
-**NixOS-WSL** on the corporate Windows machine. Headless: no Sway desktop
-(`features.swayDesktop.enable = false`), plain WSL shell login. Files:
-`configuration.nix`.
-
-## What this host is
-
-The day-to-day work environment. It layers the corporate Kubernetes / Helm /
-Terraform / cloud toolchain and a couple of work-only editor language servers on
-top of the shared home profile. The system config here is thin — it is mostly
-WSL plumbing; the user-facing tooling lives in
-[`../../users/emmathorpe/work.nix`](../../users/emmathorpe/work.nix).
-
-## WSL specifics
-
-- `wsl.enable`, default user `emmathorpe`, Windows PATH interop and start-menu
-  launchers on. `/etc/hosts` generation is off (`generateHosts = false`).
-- **Docker Desktop integration**, not the native daemon as the primary path:
-  `wsl.extraBin` shims the coreutils/`groupadd`/`usermod` binaries Docker
-  Desktop's `wsl-distro-proxy` expects, and `docker-desktop-proxy.script` is
-  patched to the real proxy path. The native `virtualisation.docker` is also
-  enabled (with `enableOnBoot` + `autoPrune`).
-- `programs.ssh.systemd-ssh-proxy.enable = false` — the NixOS-WSL store is a
-  read-only VHD owned by `nobody`, and OpenSSH rejects the generated
-  `ssh-proxy` Include as "Bad owner or permissions", which would break ssh/git
-  for every command. The vsock proxy it provides is unused under WSL.
-- `networking.hostName = "emmathorpe-edaas"` matches the flake attribute so
-  `nh os switch` resolves without `-H`.
-
-## Renovate review timer
-
-The host-table entry sets `users.emmathorpe.linger = true` so the user's
-`systemd --user` instance stays alive without an open login session. That keeps
-the daily headless **Renovate PR review** timer firing — defined in
-[`../../users/emmathorpe/renovate-review.nix`](../../users/emmathorpe/renovate-review.nix)
-(imported only from `work.nix`, so it exists on this machine alone). See that
-file's header for the auth (Vertex AI ADC), triage policy, and caveats.
-
-## stateVersion
-
-`system.stateVersion = "24.11"` — the release this box was first installed on.
-Leave it; it freezes stateful defaults and is not meant to track the current
-nixpkgs.
-
-## Apply
-
-```sh
-sudo nixos-rebuild switch --flake .#emmathorpe-edaas
-# or, since the hostname matches the attribute:
-nh os switch
-```

hosts/EDaaS/configuration.nix

@@ -62,6 +62,11 @@
 
   features.swayDesktop.enable = false;
 
+  # Opt out of fleet-wide SSSD/Authentik LDAP auth: this is a work-managed WSL
+  # box, not part of the personal directory. Every other NixOS host inherits the
+  # default-true from modules/sssd.nix.
+  services.authentikLdap.enable = false;
+
   # NOTE: this user's systemd --user lingering -- so the home-manager renovate
   # timer fires without an open login session -- is enabled from the host table
   # in flake.nix (users.emmathorpe.linger = true) and applied by

hosts/MacPro31/README.md

@@ -48,7 +48,7 @@ gigabit ports.
 ## Login
 
 Graphical login via a Wayland greeter — `greetd` running ReGreet inside the
-`cage` kiosk compositor — configured centrally in `../../modules/sway.nix` for
+`cage` kiosk compositor — configured centrally in `lyrathorpe/swaywm.nix` for
 every Sway host (gated on `features.swayDesktop.enable`). The greeter is forced
 to the Dvorak layout to match the console and Sway session. Set the user
 password (`passwd lyrathorpe`) after install, or the greeter cannot

hosts/RPi5/README.md

@@ -15,7 +15,7 @@ Headless `aarch64-linux` server with two roles:
    ```sh
    nixos-generate-config --root /mnt
    # copy /mnt/etc/nixos/hardware-configuration.nix over
-   # hosts/RPi5/hardware-configuration.nix in this repo, then commit
+   # system/machine/RPi5/hardware-configuration.nix in this repo, then commit
    ```
    `hardware-configuration.nix` in this directory is a **placeholder** committed
    only so the host evaluates in CI. The machine will not boot correctly until it
@@ -28,8 +28,7 @@ Headless `aarch64-linux` server with two roles:
    nh os switch
    ```
 4. Give the login user a password (`passwd lyrathorpe`) and confirm the key in
-   the user registry (`../../users/registry.nix`, applied by
+   `system/modules/ssh.nix` is the one you will connect with.
-   `../../modules/ssh.nix`) is the one you will connect with.
 
 ## Docker socket (security)
 

hosts/T400/README.md

@@ -35,7 +35,7 @@ change and `radeon` stays idle.
 ## Login
 
 Graphical login via a Wayland greeter — `greetd` running ReGreet inside the
-`cage` kiosk compositor — configured centrally in `../../modules/sway.nix` for
+`cage` kiosk compositor — configured centrally in `lyrathorpe/swaywm.nix` for
 every Sway host (gated on `features.swayDesktop.enable`). The greeter is forced
 to the Dvorak layout to match the console and Sway session. Set the user
 password (`passwd lyrathorpe`) after install, or the greeter cannot

modules/sssd.nix

@@ -0,0 +1,130 @@
+# Authentik LDAP authentication for NixOS hosts.
+#
+# Wires SSSD (System Security Services Daemon) to the Authentik LDAP outpost so
+# every Linux host authenticates users against the same directory that backs the
+# SSO stack. Enabled by default on every NixOS host via baseModules; the EDaaS
+# WSL box opts out (services.authentikLdap.enable = false) because it is a
+# work-managed Windows-hosted environment.
+#
+# The Authentik LDAP provider exposes NON-standard object classes/attributes
+# (goauthentik.io/ldap/user, goauthentik.io/ldap/group) alongside the POSIX
+# attributes (uid, uidNumber, gidNumber, homeDirectory), so the schema mappings
+# below are explicit rather than relying on an RFC2307 default.
+#
+# The bind password is NOT inlined: services.sssd.config renders to the world-
+# readable Nix store, so the credential is delivered out-of-band by agenix as an
+# sssd.conf drop-in under /etc/sssd/conf.d/ (SSSD merges conf.d/*.conf after the
+# main file). See secrets/README.md.
+{
+  config,
+  lib,
+  ...
+}:
+let
+  cfg = config.services.authentikLdap;
+
+  # Directory coordinates for the Authentik LDAP provider.
+  ldapUri = "ldaps://ldap.lyrapup.pet:636";
+  searchBase = "dc=ldap,dc=goauthentik,dc=io";
+  bindDn = "cn=sssd-bind,ou=users,dc=ldap,dc=goauthentik,dc=io";
+in
+{
+  options.services.authentikLdap.enable =
+    lib.mkEnableOption "SSSD authentication against the Authentik LDAP outpost"
+    // {
+      default = true;
+    };
+
+  config = lib.mkIf cfg.enable {
+    services.sssd = {
+      enable = true;
+
+      # Non-secret sssd.conf. The bind password is injected separately via the
+      # agenix conf.d drop-in (ldap_default_authtok lives there, not here) to
+      # keep it out of the Nix store.
+      config = ''
+        [sssd]
+        config_file_version = 2
+        services = nss, pam
+        domains = default
+
+        [nss]
+        # Do not walk the whole directory for `getent passwd` etc.
+        filter_users = root
+        filter_groups = root
+
+        [pam]
+
+        [domain/default]
+        # --- Providers --------------------------------------------------------
+        id_provider = ldap
+        auth_provider = ldap
+        chpass_provider = none
+        access_provider = permit
+
+        # --- Connection -------------------------------------------------------
+        ldap_uri = ${ldapUri}
+        ldap_search_base = ${searchBase}
+        ldap_default_bind_dn = ${bindDn}
+        ldap_default_authtok_type = password
+        # ldap_default_authtok is supplied by the agenix drop-in in conf.d.
+
+        # --- TLS (LDAPS on 636; no StartTLS) ---------------------------------
+        ldap_id_use_start_tls = false
+        ldap_tls_reqcert = demand
+
+        # --- Schema: Authentik LDAP provider ---------------------------------
+        # Authentik returns DN-valued group membership (member/memberOf), so
+        # rfc2307bis (not rfc2307) is the correct base schema.
+        ldap_schema = rfc2307bis
+
+        # Users: goauthentik.io/ldap/user, keyed by uid; POSIX attrs are
+        # standard names (uidNumber/gidNumber/homeDirectory).
+        ldap_user_object_class = goauthentik.io/ldap/user
+        ldap_user_name = uid
+        ldap_user_uid_number = uidNumber
+        ldap_user_gid_number = gidNumber
+        ldap_user_home_directory = homeDirectory
+        ldap_user_gecos = displayName
+        ldap_user_shell = loginShell
+
+        # Groups: goauthentik.io/ldap/group, keyed by cn.
+        ldap_group_object_class = goauthentik.io/ldap/group
+        ldap_group_name = cn
+        ldap_group_gid_number = gidNumber
+        ldap_group_member = member
+
+        # --- Behaviour --------------------------------------------------------
+        cache_credentials = true
+        enumerate = false
+      '';
+    };
+
+    # agenix delivers the bind password as an sssd.conf drop-in. The decrypted
+    # plaintext IS a valid conf.d snippet:
+    #
+    #   [domain/default]
+    #   ldap_default_authtok = <the bind password>
+    #
+    # SSSD requires conf.d files to be root-owned and 0600 or it ignores them.
+    age.secrets.ldap-bind = {
+      file = ../secrets/ldap-bind.age;
+      path = "/etc/sssd/conf.d/01-ldap-authtok.conf";
+      owner = "root";
+      group = "root";
+      mode = "0600";
+    };
+
+    # Restart SSSD when the credential drop-in changes. agenix writes secrets in
+    # a system activation script that runs before systemd (re)starts services on
+    # a `switch`, so the file is present by the time sssd starts; the trigger
+    # picks up rotations of the bind password.
+    systemd.services.sssd.restartTriggers = [ config.age.secrets.ldap-bind.path ];
+
+    # Create home directories on first login for LDAP users (they have no
+    # locally-provisioned home). NixOS wires nss + the SSSD PAM stack when
+    # services.sssd.enable is true; mkHomeDir adds pam_mkhomedir to it.
+    security.pam.services.login.makeHomeDir = true;
+    security.pam.services.sshd.makeHomeDir = true;
+  };
+}

secrets/README.md

@@ -0,0 +1,92 @@
+# Secrets (agenix)
+
+Encrypted secrets for the fleet, managed with [agenix](https://github.com/ryantm/agenix).
+
+Each secret is an age-encrypted file (`*.age`) encrypted to a set of recipient
+public keys declared in [`secrets.nix`](./secrets.nix). A host decrypts its
+secrets at activation using its SSH **host** key
+(`/etc/ssh/ssh_host_ed25519_key`), so every host that must read a secret has to
+be listed as a recipient for it.
+
+`secrets.nix` is read only by the `agenix` CLI. It is never imported into the
+NixOS evaluation.
+
+## Secrets in this repo
+
+| File            | Purpose                                                                 | Recipients                          |
+| --------------- | ----------------------------------------------------------------------- | ----------------------------------- |
+| `ldap-bind.age` | SSSD → Authentik LDAP bind credential, as an `sssd.conf` drop-in snippet | all SSSD-enabled hosts (not EDaaS)  |
+
+Consumed by [`modules/sssd.nix`](../modules/sssd.nix) via
+`age.secrets.ldap-bind.path`, which places the decrypted snippet at
+`/etc/sssd/conf.d/01-ldap-authtok.conf`.
+
+> **`ldap-bind.age` is not committed yet.** Only `ldap-bind.age.PLACEHOLDER`
+> ships in this change (real host recipient keys and the real password were not
+> available when it was written). Follow the steps below to create the real
+> secret, then delete the `.PLACEHOLDER`.
+
+## Owner setup checklist
+
+Run these once (per new host or when the bind password rotates):
+
+### 1. Collect host recipient keys
+
+On each SSSD-enabled host (all Linux hosts **except** EDaaS):
+
+```sh
+cat /etc/ssh/ssh_host_ed25519_key.pub
+```
+
+Paste each value into the matching placeholder in `secrets.nix`, replacing the
+`AAAA_PLACEHOLDER_REPLACE_ME_*` strings. (Optionally uncomment and set `admin`
+to an operator user key so the secret can be edited off-host.)
+
+### 2. Encrypt the bind password
+
+The plaintext must be a **full sssd.conf drop-in snippet**, because SSSD cannot
+read `ldap_default_authtok` from a separate file — it only merges `conf.d/*.conf`.
+The content is exactly:
+
+```ini
+[domain/default]
+ldap_default_authtok = <the sssd-bind service-account password>
+```
+
+Use the password of the `sssd-bind` (Terraform: `sssd-bind`) Authentik LDAP
+service account. Then, from the repo root:
+
+```sh
+# Requires the agenix CLI: `nix run github:ryantm/agenix -- -e secrets/ldap-bind.age`
+cd secrets
+agenix -e ldap-bind.age
+```
+
+An `$EDITOR` opens; paste the two-line snippet above, save, quit. agenix writes
+the encrypted `ldap-bind.age`. Commit it and delete `ldap-bind.age.PLACEHOLDER`.
+
+### 3. Rekey after changing recipients
+
+If you add/remove hosts in `secrets.nix`, re-encrypt every secret to the new
+recipient set:
+
+```sh
+cd secrets
+agenix -r
+```
+
+### 4. DNS
+
+`ldap.lyrapup.pet` must resolve to the Authentik LDAP outpost and serve LDAPS on
+port 636 with a certificate the hosts trust (`ldap_tls_reqcert = demand`). If the
+cert is not from a system-trusted CA, add it to the hosts' trust store
+(`security.pki.certificateFiles`) or relax `ldap_tls_reqcert` in
+`modules/sssd.nix`.
+
+### 5. Rebuild
+
+```sh
+sudo nixos-rebuild switch --flake .#<host>
+```
+
+Verify with `getent passwd <ldap-user>` and `id <ldap-user>`.

secrets/ldap-bind.age.PLACEHOLDER

@@ -0,0 +1,21 @@
+THIS IS A PLACEHOLDER, NOT A REAL AGE SECRET.
+
+The real secrets/ldap-bind.age is produced by the repo owner with `agenix -e`
+(see secrets/README.md) and is a binary age-encrypted blob. It is intentionally
+NOT committed here because:
+  * the real host age recipients are not available to the author of this change
+    (they are each host's /etc/ssh/ssh_host_ed25519_key.pub), and
+  * fabricating an encrypted blob or fake host keys would be misleading.
+
+Committing this file as `ldap-bind.age` would let modules/sssd.nix reference
+`../secrets/ldap-bind.age` and evaluate, but SSSD would fail to decrypt it at
+runtime. Do ONE of the following before deploying:
+
+  1. Preferred: generate the real secret (secrets/README.md), commit it as
+     secrets/ldap-bind.age, and delete this .PLACEHOLDER file.
+
+The decrypted plaintext must be a valid sssd.conf drop-in (NOT the bare
+password):
+
+    [domain/default]
+    ldap_default_authtok = <the sssd-bind service-account password>

secrets/secrets.nix

@@ -0,0 +1,15 @@
+let
+  lyrathorpe-mbp = "ssh-ed25519 AAAA_PLACEHOLDER_REPLACE_ME_mbp";
+  lyrathorpe-t400 = "ssh-ed25519 AAAA_PLACEHOLDER_REPLACE_ME_t400";
+  lyrathorpe-macpro31 = "ssh-ed25519 AAAA_PLACEHOLDER_REPLACE_ME_macpro31";
+  lyrathorpe-rpi5 = "ssh-ed25519 AAAA_PLACEHOLDER_REPLACE_ME_rpi5";
+  sssdHosts = [
+    lyrathorpe-mbp
+    lyrathorpe-t400
+    lyrathorpe-macpro31
+    lyrathorpe-rpi5
+  ];
+in
+{
+  "ldap-bind.age".publicKeys = sssdHosts;
+}