feat(work): headless Secret Service for gcx keychain tokens

gcx stores its OAuth access and refresh tokens in the system keychain
unconditionally -- its config file keeps only opaque `keychain:gcx:v2:...`
handles -- and exposes no plaintext fallback. With nothing owning
org.freedesktop.secrets on this headless WSL box, `gcx login` authenticates
against Grafana and then dies writing its config: "The name is not activatable".

Add services.headlessSecretService: gnome-keyring as a systemd --user service,
unlocking the login keyring at start. home-manager's own services.gnome-keyring
does not fit here on two counts -- it is WantedBy graphical-session-pre.target,
which never activates without a desktop session, and it passes no --unlock, so
writes would block on a GUI prompter that does not exist.

Only the secrets component is started. The ssh component is deliberately off: it
would claim SSH_AUTH_SOCK and displace services.ssh-agent, breaking SSH auth and
signed commits.

The unlock password defaults to a random one generated on first activation under
$XDG_DATA_HOME. The passwordFile option is the seam for supplying it from an
agenix secret instead, once that lands.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

README.md

@@ -30,7 +30,7 @@ profiles. The full module catalogue is below.
 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
+home/                  # home-manager profile: shell, git, editor, claude, secret-service, 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)
@@ -94,8 +94,9 @@ 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
+  toolchain (kubectl/helm/az/etc.), work-only LSP servers, the corporate ssh
-  handling; imports
+  handling, and the headless Secret Service that gcx needs for its keychain
+  tokens (see [`home/secret-service.nix`](./home/secret-service.nix)); imports
   [`users/emmathorpe/renovate-review.nix`](./users/emmathorpe/renovate-review.nix),
   the daily headless Renovate-PR review timer (EDaaS only).
 

flake.nix

@@ -435,6 +435,7 @@
           git = ./home/git.nix;
           editor = ./home/editor.nix;
           claude = ./home/claude.nix;
+          secret-service = ./home/secret-service.nix;
           desktop = ./home/desktop.nix;
           sway = ./home/sway.nix;
         };

home/default.nix

@@ -8,6 +8,9 @@
     ./git.nix
     ./editor.nix
     ./claude.nix
+    # Declares services.headlessSecretService; opt-in, off by default. Graphical
+    # hosts should prefer home-manager's own services.gnome-keyring.
+    ./secret-service.nix
   ];
 
   # Manage the XDG base-directory layout and ~/.config files. Tools above

home/secret-service.nix

@@ -0,0 +1,142 @@
+# Headless Secret Service (org.freedesktop.secrets) on the user session bus,
+# for CLI tools that keep credentials in the system keychain rather than in a
+# config file of their own.
+#
+# Current consumer: gcx, the Grafana Cloud CLI (users/emmathorpe/work.nix). gcx
+# stores its OAuth access and refresh tokens in the keychain unconditionally --
+# its config file holds only opaque `keychain:gcx:v2:...` handles -- and offers
+# no plaintext fallback (there is no environment variable or config key to
+# select a file-backed store). With nothing owning org.freedesktop.secrets,
+# `gcx login` authenticates against Grafana successfully and then dies writing
+# its config: "The name is not activatable".
+#
+# home-manager already ships services.gnome-keyring, but it does not fit a
+# headless host on two counts:
+#
+#   * it is WantedBy graphical-session-pre.target, which never activates
+#     without a desktop session, so the service would simply never start; and
+#   * it cannot unlock the login keyring (it passes no --unlock). An unlocked
+#     collection is mandatory: writing to a locked one blocks on a GUI prompter
+#     (gcr) that does not exist here, so the caller hangs rather than fails.
+#
+# Security posture, stated plainly: the login keyring is encrypted at rest, but
+# the password unlocking it is readable by the same user on the same machine.
+# That protects the tokens from something reading the keyring file directly; it
+# protects them from nothing already running as this user. It is the same
+# posture as the existing ~/.jenkinsenv and ~/.splunkenv token files, and it is
+# the price of unattended operation -- systemd --user timers start with no
+# human present to type a passphrase.
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  cfg = config.services.headlessSecretService;
+
+  # Where the generated unlock password lives when no external passwordFile is
+  # supplied. Under $XDG_DATA_HOME rather than the nix store, which is
+  # world-readable.
+  defaultPasswordFile = "${config.xdg.dataHome}/gnome-keyring/login-password";
+
+  passwordFile = if cfg.passwordFile != null then cfg.passwordFile else defaultPasswordFile;
+
+  keyringDaemon = pkgs.writeShellApplication {
+    name = "headless-secret-service";
+    runtimeInputs = [
+      pkgs.gnome-keyring
+      pkgs.coreutils
+    ];
+    text = ''
+      pwfile=${lib.escapeShellArg passwordFile}
+
+      if [ ! -s "$pwfile" ]; then
+        echo "headless-secret-service: no keyring password at $pwfile" >&2
+        exit 1
+      fi
+
+      # The daemon takes the whole of stdin as the password, so a trailing
+      # newline would silently become part of it. Strip it, so a hand-written or
+      # agenix-managed file unlocks the same keyring the generated one created.
+      #
+      # --components=secrets ONLY. The ssh component must stay off: it would
+      # claim SSH_AUTH_SOCK and displace services.ssh-agent, breaking SSH auth
+      # and signed commits. pkcs11 is not needed by anything here.
+      tr -d '\n' <"$pwfile" |
+        exec gnome-keyring-daemon --foreground --components=secrets --unlock
+    '';
+  };
+in
+{
+  options.services.headlessSecretService = {
+    enable = lib.mkEnableOption ''
+      a headless gnome-keyring serving org.freedesktop.secrets on the user
+      session bus, with the login keyring unlocked at service start'';
+
+    passwordFile = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = null;
+      example = "/run/agenix/gnome-keyring-login";
+      description = ''
+        Path to a file holding the login keyring password. It is read at service
+        start, not at build time, so it need not exist when the system is built
+        -- this is the seam for an agenix-managed secret.
+
+        When null, a random 32-byte password is generated on first activation at
+        ${defaultPasswordFile} (mode 0600) and reused from then on.
+
+        Pointing this at a different file after the login keyring already exists
+        does NOT re-key the keyring: the daemon will fail to unlock it. To
+        change the password, delete ~/.local/share/keyrings and re-authenticate
+        every tool that stored a secret there.
+      '';
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    # secret-tool, for inspecting or repairing the keyring by hand when a stored
+    # credential misbehaves (`secret-tool search --all service gcx`).
+    home.packages = [ pkgs.libsecret ];
+
+    # Generate the unlock password on first activation. Guarded on us owning it:
+    # an externally supplied passwordFile is never created or written here.
+    home.activation = lib.mkIf (cfg.passwordFile == null) {
+      headlessSecretServicePassword = lib.hm.dag.entryAfter [ "writeBoundary" ] ''
+        pwfile=${lib.escapeShellArg defaultPasswordFile}
+        if [ ! -s "$pwfile" ]; then
+          run mkdir -p "$(dirname "$pwfile")"
+          # Create the file empty at 0600 first, then fill it: the redirect
+          # keeps the existing mode, so the password is never briefly readable.
+          run install -m 600 /dev/null "$pwfile"
+          run ${pkgs.bash}/bin/sh -c \
+            'head -c 32 /dev/urandom | base64 -w0 > "$1"' sh "$pwfile"
+        fi
+      '';
+    };
+
+    systemd.user.services.headless-secret-service = {
+      Unit = {
+        Description = "GNOME Keyring (Secret Service, headless)";
+        Documentation = "man:gnome-keyring-daemon(1)";
+        # The daemon claims its name on the user session bus.
+        Requires = [ "dbus.socket" ];
+        After = [ "dbus.socket" ];
+      };
+
+      Service = {
+        Type = "simple";
+        ExecStart = lib.getExe keyringDaemon;
+        Restart = "on-failure";
+        RestartSec = 2;
+      };
+
+      # default.target, not graphical-session-pre.target: there is no graphical
+      # session on this host. With `linger` enabled (see the host table in
+      # flake.nix) default.target is reached at boot, so the keyring is also up
+      # for unattended systemd --user timers, not just interactive logins.
+      Install.WantedBy = [ "default.target" ];
+    };
+  };
+}

hosts/EDaaS/README.md

@@ -38,6 +38,40 @@ the daily headless **Renovate PR review** timer firing — defined in
 (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.
 
+## Secret Service (keychain)
+
+`work.nix` sets `services.headlessSecretService.enable = true`, which runs
+`gnome-keyring` as a `systemd --user` service owning `org.freedesktop.secrets`
+on the session bus, with the login keyring unlocked at start.
+
+This exists for **gcx**, the Grafana Cloud CLI. gcx stores its OAuth access and
+refresh tokens in the keychain unconditionally (its config keeps only opaque
+`keychain:gcx:v2:...` handles) and has no plaintext fallback, so without a
+Secret Service `gcx login` authenticates and then fails to persist with "The
+name is not activatable".
+
+Home-manager's own `services.gnome-keyring` does not work here: it is
+`WantedBy=graphical-session-pre.target`, which never activates on this headless
+box, and it cannot unlock the keyring. See
+[`../../home/secret-service.nix`](../../home/secret-service.nix) for the full
+rationale and the security trade-off of an auto-unlocked keyring.
+
+Only the `secrets` component is started. The `ssh` component is deliberately off
+— it would claim `SSH_AUTH_SOCK` and displace `services.ssh-agent`, breaking SSH
+auth and signed commits.
+
+Checking it:
+
+```sh
+systemctl --user status headless-secret-service
+busctl --user list | grep secrets     # expect org.freedesktop.secrets
+secret-tool search --all service gcx  # inspect what gcx stored
+gcx config check                      # end-to-end
+```
+
+If the keyring password is ever lost or changed, the login keyring cannot be
+unlocked: delete `~/.local/share/keyrings` and re-run `gcx login`.
+
 ## stateVersion
 
 `system.stateVersion = "24.11"` — the release this box was first installed on.

users/emmathorpe/work.nix

@@ -49,6 +49,13 @@
     pkgs.gcx # Grafana Cloud CLI (dashboards, SLOs, synthetics, alerts)
   ];
   services.ssh-agent.enable = true;
+
+  # gcx (above) keeps its OAuth tokens in the system keychain and has no
+  # plaintext fallback, so this WSL box needs something owning
+  # org.freedesktop.secrets. See home/secret-service.nix for why
+  # home-manager's services.gnome-keyring cannot be used on a headless host,
+  # and for the security trade-off of an auto-unlocked keyring.
+  services.headlessSecretService.enable = true;
   home.shellAliases = {
     docker = "/run/current-system/sw/bin/docker";
   };