headscale: add OIDC login, stop overriding clients' local DNS

Two changes to the control server, plus the fallout on the hosts.

OIDC via Authentik, so `tailscale up --login-server ...` opens a browser
instead of needing a pre-auth key. This is a second Authentik application,
separate from headplane's, with headscale's own /oidc/callback redirect.
Headless hosts keep using pre-auth keys. Note that headscale runs OIDC
discovery at startup and a failure is FATAL -- pointing `issuer` at an
application that does not exist yet means the control server will not
boot, so verify the discovery document before deploying.

override_local_dns = false, because the upstream default of true replaces
resolv.conf with 100.100.100.100 on every node. That silently broke the
LAN's `.sol` names -- pihole serves those and the global nameservers
return NXDOMAIN for them -- and took ad blocking down with them. It also
made each node's entire DNS depend on tailscaled, which is what had
forced --accept-dns=false onto neptun and mercury individually; both of
those workarounds are now removed, and with MagicDNS resolving properly
again neptun no longer needs its hardcoded /etc/hosts pin for jupiter.

Also serves jellyfin and seerr from jupiter, matching the ports they
already use on its LAN vhosts, and rotates the tailnet pre-auth keys.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

hosts/mercury/configuration.nix

@@ -28,19 +28,9 @@
   networking.interfaces.eth0.ipv6.addresses = [
     { address = "fd18:df17:9078:0::10"; prefixLength = 64; }
   ];
-  # VERIFY with `ip route` on the Pi — assuming the router is .1.
   networking.defaultGateway = { address = "10.0.0.1"; interface = "eth0"; };
-  # Resolvers for the Pi's OWN lookups (not the LAN service). Kept public so the
-  # host resolves during boot without depending on its own pihole/unbound.
   networking.nameservers = [ "1.1.1.1" "9.9.9.9" ];
 
-  # Never take MagicDNS on THIS host. headscale pushes override_local_dns, so
-  # accepting it would repoint mercury's resolv.conf at 100.100.100.100 and
-  # make the LAN's DNS server depend on tailscaled to resolve anything — the
-  # same boot-time DNS deadlock this host already hit once (see CLAUDE.md),
-  # except a failure here takes the whole network's DNS down with it.
-  services.tailscale.extraUpFlags = [ "--accept-dns=false" ];
-
   # ---- pihole web admin password (from sops) ----
   # The pihole container reads FTLCONF_* env vars. Render an env file from the
   # sops secret and feed it to the container — password stays out of repo/store.

hosts/neptun/configuration.nix

@@ -43,20 +43,6 @@
   networking.defaultGateway6 = { address = "fe80::1"; interface = "eth0"; };
   networking.nameservers = [ "9.9.9.9" "1.1.1.1" "2620:fe::fe" ];
 
-  # ---- Don't take MagicDNS from our own control server ----
-  # headscale pushes override_local_dns, so joining the tailnet would point
-  # neptun's resolv.conf at a MagicDNS served by the tailscaled neptun itself
-  # hosts. A tailscaled failure would then also kill DNS, and with it ACME
-  # renewal — expiring the certs for the very control server every other node
-  # needs to recover. Keep the public resolvers above and resolve the one
-  # tailnet name we proxy to from /etc/hosts instead.
-  services.tailscale.extraUpFlags = [ "--accept-dns=false" ];
-
-  # ⚠️  PLACEHOLDER IP — replace once jupiter first enrols, with its address
-  #     from `headscale nodes list` on this box. Until then the audiobookshelf
-  #     vhost and the gitea SSH forward below both fail to connect.
-  networking.hosts."100.64.0.2" = [ "jupiter.hosts.mgaction.town" ];
-
   # firewall (enable + 22), caddy (80/443), tailscale (trust tailscale0 + join
   # headscale) come from ../../common.nix and ../../services/{caddy,tailscale}.nix.
 
@@ -71,21 +57,49 @@
   # ---- Public reverse proxy vhosts ----
   # Caddy gets automatic public HTTPS (Let's Encrypt) for real domains; the
   # *.mgaction.town wildcard already points every name here (A + AAAA), and
-  # the module opens 80/443. Both of these live on jupiter and are reached
+  # the module opens 80/443. All of these live on jupiter and are reached over
-  # over the tailnet — see the /etc/hosts pin above.
+  # the tailnet by their MagicDNS name, which resolves because headscale no
-  #
+  # longer overrides local DNS (see services/vpn/headscale.nix).
-  # `abs`, not `audiobookshelf`: that's the name this has always been served
+
-  # under, and the mobile app is configured with it.
+  # ---- Audiobookshelf ----
   services.caddy.virtualHosts."abs.mgaction.town".extraConfig = ''
     reverse_proxy http://jupiter.hosts.mgaction.town:8000
   '';
+
+  # ---- Seerr ----
+  services.caddy.virtualHosts."seerr.mgaction.town".extraConfig = ''
+    reverse_proxy http://jupiter.hosts.mgaction.town:5055
+  '';
+
+  # ---- Jellyfin ----
+  services.caddy.virtualHosts."jellyfin.mgaction.town".extraConfig = ''
+    reverse_proxy http://jupiter.hosts.mgaction.town:8096
+  '';
+
+  # ---- Gitea WebUI ----
   # Gitea's web UI and HTTPS clones (services/dev/gitea.nix, HTTP_PORT 3000).
   # Its SSH side is the separate :2222 forward further down.
   services.caddy.virtualHosts."git.mgaction.town".extraConfig = ''
     reverse_proxy http://jupiter.hosts.mgaction.town:3000
   '';
-  # The apex mgaction.town is deliberately not served — it returns Caddy's
+
-  # default 404.
+  # ---- Gitea SSH forward ----
+  # Caddy only proxies HTTP; forward :2222 over the tailnet to gitea's own
+  # SSH server on jupiter (services/dev/gitea.nix), so
+  # `ssh://git@git.mgaction.town:2222/...` works. Also needs a matching
+  # inbound-2222 rule in netcup's edge firewall panel (not managed by Nix).
+  systemd.services.gitea-ssh-forward = {
+    description = "Forward :2222 to jupiter's gitea SSH server over tailscale";
+    after = [ "network-online.target" "tailscaled.service" ];
+    wants = [ "network-online.target" ];
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      DynamicUser = true;
+      ExecStart = "${pkgs.socat}/bin/socat TCP-LISTEN:2222,fork,reuseaddr TCP:jupiter.hosts.mgaction.town:2222";
+      Restart = "always";
+    };
+  };
+  networking.firewall.allowedTCPPorts = [ 2222 ];
 
   # ---- Authentik (identity/OIDC provider) ----
   # Runs locally on neptun (see services/identity/authentik.nix); Caddy just
@@ -113,23 +127,5 @@
     }
   '';
 
-  # ---- Gitea SSH forward ----
-  # Caddy only proxies HTTP; forward :2222 over the tailnet to gitea's own
-  # SSH server on jupiter (services/dev/gitea.nix), so
-  # `ssh://git@git.mgaction.town:2222/...` works. Also needs a matching
-  # inbound-2222 rule in netcup's edge firewall panel (not managed by Nix).
-  systemd.services.gitea-ssh-forward = {
-    description = "Forward :2222 to jupiter's gitea SSH server over tailscale";
-    after = [ "network-online.target" "tailscaled.service" ];
-    wants = [ "network-online.target" ];
-    wantedBy = [ "multi-user.target" ];
-    serviceConfig = {
-      DynamicUser = true;
-      ExecStart = "${pkgs.socat}/bin/socat TCP-LISTEN:2222,fork,reuseaddr TCP:jupiter.hosts.mgaction.town:2222";
-      Restart = "always";
-    };
-  };
-  networking.firewall.allowedTCPPorts = [ 2222 ];
-
   system.stateVersion = "26.05";   # set at install time; do NOT bump on upgrades
 }

hosts/neptun/secrets.nix

@@ -43,9 +43,14 @@
   # placeholders (see services/vpn/headplane.nix) until Authentik/headscale are
   # actually deployed and those get created for real.
   #
-  # owner: unlike authentik's EnvironmentFile above, headplane opens these
+  # owner: unlike authentik's EnvironmentFile above, headscale and headplane
-  # paths itself, already running as headscale's user — so root:root 0400
+  # open these paths themselves, already running as the headscale user — so
-  # would fail and each needs an explicit owner.
+  # the root:root 0400 default would fail and each needs an explicit owner.
+  #
+  # headscale's OIDC client is a SEPARATE Authentik application from
+  # headplane's (services/vpn/headscale.nix), hence the second client secret.
+  sops.secrets.headscale_oidc_client_secret.owner = "headscale";
+
   sops.secrets.headplane_cookie_secret.owner = "headscale";
   sops.secrets.headplane_oidc_client_secret.owner = "headscale";
   sops.secrets.headplane_headscale_api_key.owner = "headscale";

secrets/jupiter.yaml

@@ -1,6 +1,6 @@
 samba_password: ENC[AES256_GCM,data:K3FtKC0CrOLMyfQokmxxlyUnDPo=,iv:9bTE/S/i05LJYldOHuBuz3+g8JdTuq0ysFFgXOmfti8=,tag:77NIxy7qpHRqCmbOR83AfA==,type:str]
 darman_password: ENC[AES256_GCM,data:DOHHlM4Qdw4WgkN+/M51n2LMjJqq5MS0FeGEH8Pz3297yUZ8jBDOKRS/Tek9stC05JKEQRtn/vVVbAY0nXs20MwrsDMo+IEFXx7Ms90vVyYIYe5O5/0aQkPq84vcwGN0RW1Rj5Y3s38vWA==,iv:DAqHbvOBq7FT7ALbmBXJ0HadEGEsL8V2e7R99H5ZH0s=,tag:9XpiRFIbaZjMn59uHCOA1g==,type:str]
-tailscale_authkey: ENC[AES256_GCM,data:LjRXyFW1SbhUiXbCQnRKinJluGfQWsjS7TTP/TMvx2noP6aFNrcYMvitG+OqLAlNEQAy0bcxZejZgJN+yNS+5iuy2F7OXhrpO7Df0JHkyMvQpnaH2XBEsw==,iv:QxVkB6GtZOYWFAOFVdBQMU2Hb/2OwBRCLHdfxoDF/ME=,tag:PBL0TV6yZJSu4+TGpycf/A==,type:str]
+tailscale_authkey: ENC[AES256_GCM,data:dwBoHIJNcRSLxk1rbMsrEHVoYdxdnvYpPq44utfQ8t4XkXEzto96FEctv/QuPYVGgUxdyPczmc0/97m4AAKjaBVGFXpt/XlnFQI2XgzgSJ0qhNWyfJ1F/g==,iv:1b9nMeeZwr4O8cKjxQ0f+j/yxMUBZpicmdXw7bb9hZk=,tag:FWgrKtKgqailQk+BcZNXhw==,type:str]
 mediamanager_token_secret: ENC[AES256_GCM,data:g75vj1E6B029O076yV3DS/1z99Tq6wMhEVx+ULYDjHsplyA+vqVRvBlviC64V47IMqKd9k2eTGBJ98Ptv3UIjbr446xZinz0c7PZgHU0XOX4EUcB1ORloMFZIv1zUv8VRjUISUQnn/vRk60e7u8eXrOrgXjxfnoBKrdKZmqxhAM=,iv:2t0XBExC9RvbTomezka+99/LtJl64zNwneA7WWc4ju0=,tag:SVCYuw0n6JevnvoQOIkjPw==,type:str]
 sabnzbd_api_key: ENC[AES256_GCM,data:6UW1u2Ikmnq34t4H4k/4C44SJeFHRlaPjWwUjEfH1GQ=,iv:sGsd8Sd2pfUhTUDg6PlRzfVYejRbF69jmDTIa2fvY4M=,tag:3fOLgU1K1gKHxQ3J1+3oRQ==,type:str]
 prowlarr_api_key: ENC[AES256_GCM,data:ab1QACaagI8ACJXFUy8r9X9lgYwRo1byUmhBPSRWwKk=,iv:EcuF6EN/4mWxlXi6R1qDzv4rOw6AT+OGSNQaaBwjJHg=,tag:hixHrbQWU6QQZNMM5rNDsg==,type:str]
@@ -25,7 +25,7 @@ sops:
             CzjSDQZTcseEXZNwuzZcfB5Mvq0BQvjOj7lGuxzuE4qwWkdJWGfVLQ==
             -----END AGE ENCRYPTED FILE-----
           recipient: age1zak7glavmg4026p2389fyqe769vqm4jrryknuqckgqq4merz5f7q44rkkt
-    lastmodified: "2026-07-20T07:51:55Z"
+    lastmodified: "2026-07-20T18:42:14Z"
-    mac: ENC[AES256_GCM,data:CBQrHpdIOn35CIrZaqZqZd/V4pp+bMNygXJoYwlOvwAtb49ElqmQgSZxWVgTKpTNZpMkqYie6HQB0c4vsmU/BYeLQKJNYBQvBxIrTQr4wMURj2jBMhtVT2osX5cUpNakoHZUdz6ARXyYGEVOBzMY77vSxk6VkVi5CFmeOETkcik=,iv:a6iTeIlR2S65pTrH+juS6kEhpbiaAmhcPLssasUPZ58=,tag:QP+LMclWU9SO5/uPI/Nwwg==,type:str]
+    mac: ENC[AES256_GCM,data:l9O/KAd/5KfC+LXwE2y5+ybflyy9Xl0PikoRfcOzIFu+fVWESyi0D22emWen6J4mpvsXgjAp4GCu4RKNTGyy47mfkaHh/KdxozEOmP8VlKOJXtqzU9lTgZwhHqkF9RKsRLKHvmREugwzWnpplJ8J7bg5Z3llBIM36FlElzQ9hUw=,iv:x0lM9Ctcn1XCsXftB9Ze8WV8Rp4YA26MQ/AdGC78MyY=,tag:gtfaSDQAcAkngRw2Ph2N0A==,type:str]
     unencrypted_suffix: _unencrypted
     version: 3.13.1

secrets/mercury.yaml

@@ -1,6 +1,6 @@
 darman_password: ENC[AES256_GCM,data:iZQERcXtyH+91yUc3r7U6jnFYrGQPFeCPk/9ZDfxOhPLlGMX3/iEZ+SzZ7a7rDKUeUAaQUsrqANLDLclRYm4Ngo09EkbDxBx5x2GpQwlqSAS45LHnTen9LTzisWghdy79Xnilq322eaB3g==,iv:ozx/BPLR8nZTKHZroKrrh2z6ZlVCuLydQ3aNY4XvcIg=,tag:CSrq5ZipYxtXTT8RintuHQ==,type:str]
 pihole_webpassword: ENC[AES256_GCM,data:5iOTqD0CcbOCnM1b4+RbajMTyAU=,iv:2ZRW7dshnPzWkuudrn6n92y4Z2n/6fdnBB7BO5/ypS4=,tag:8UZSqJM6dVECQgrF6v5Fuw==,type:str]
-tailscale_authkey: ENC[AES256_GCM,data:CZe1wkh2DNF2g4wy30Wph0c4/3f1M2K9Up+3oAcLEVdZjJzLRJotAU/0Nw2PSGoDZTtqOSfDaEXsaa45DBIJj2EUvWKSYrkV4XkLCio6ZWoGhmxH9PYfkw==,iv:UqNZz7grRPT/d1a2Tv1PW4H2k5FeZCuDy/fK+jVou9E=,tag:cYbLk+7JqU/1by8j2ri0Xg==,type:str]
+tailscale_authkey: ENC[AES256_GCM,data:Ogm5RTcbJl5lsL19qgTcqXLWK7ypxXrAHNYgriduQQSSRoRWvsnJ3A2Lbynb+r756WxJyFSFqY3WGr9pHaCYo8LAf5oD1MJE26I7JtsAVcHY0QS29b2MnQ==,iv:3H0YMk6llOBapqtMkxsdlY8wQhzIXa+6W4ZrWD0iq2M=,tag:3rPQS7FX8ODLAQK5gOL7lw==,type:str]
 sops:
     age:
         - enc: |
@@ -21,7 +21,7 @@ sops:
             x6FfYadcRfqvSX60l6+TGdzq6xDpxLIZOJ8q19qZsAvB0in50HW5gg==
             -----END AGE ENCRYPTED FILE-----
           recipient: age1cpty7zrgnn6l97upq00w5wa8zcvnkxkdt2jvhlj97jh83exure4slha43t
-    lastmodified: "2026-07-20T08:31:19Z"
+    lastmodified: "2026-07-20T18:41:59Z"
-    mac: ENC[AES256_GCM,data:kdWGhCOENvnUAnwbLW58JH8Ur+g+f4Z1pr3seZGGOFa04xeXb5HOzegpIH+x7OT5OvsKZsMKWf7sBGgB/nx+m2ZKy4NLC39dLbV8V5hs18NhRKl5vKZBZHE1D2xAK4+REwRYT6LiXArQssPv9e2q5fcW6q3rtnlHMF0tUsWip9o=,iv:BkKv2ZBxZMX4agHTzF2Mcmasxpp+hqkiu9mH0mUeLS4=,tag:t0MeKRPikYR5MAmU8r77sg==,type:str]
+    mac: ENC[AES256_GCM,data:Ay3JLVmJu9S5wlxyL5mrACgLv+jbAsKB5/5r8/z5m4fPjfaYnBQbn1b2s8G764yI0+L3JVWyAdvdy2Gqplrds87lWqlf+gpJKGOoargsiIZAfJmJEzZOYZLPT8YanvGMHniAJszeZ9CnL7Uf9fn0RpT4ObeT7didSqIds6xVeRs=,iv:whZ9L1+tMTkTZaVUdshghIsS9Gmde4RozMDe3XN1ek8=,tag:015mccmr9A/YW+7E+1CsGg==,type:str]
     unencrypted_suffix: _unencrypted
     version: 3.13.1

secrets/neptun.yaml

@@ -2,10 +2,11 @@ darman_password: ENC[AES256_GCM,data:7G2Hgh13TxI6ugw2ebp9UtLTQ7HRC/hrCga0FmZo8h8
 authentik_secret_key: ENC[AES256_GCM,data:qLrAWBywlMqT6D3FYDqE9I/5Ep+zDVu9ns9TA4UVOBSQ1uFGEj01TU9norqPf12pi9/Qs32mVzm5BqDG259DxdGT9DZVQc03QVwiIQYtmWo=,iv:OVCIxIP1Xv+nHmYsrxaPgYWQiwzVPUe8pnbyMBVAuoI=,tag:+ywkwPqkY1Dkx1R5cUJ7PA==,type:str]
 authentik_bootstrap_email: ENC[AES256_GCM,data:OmqpKAiiFyS/rytnHYRZ,iv:VXiPV5VfduC/IW+E3gDlNAeE+hr+IZ9W7Ty6Npuu59Y=,tag:rjvTHnBxN/pMvpQC5W9S6Q==,type:str]
 authentik_bootstrap_password: ENC[AES256_GCM,data:QPCY0ni3jBQY5HyK+vRlyT4YTEo=,iv:41u1Jf+WYksPUY4pvKdHQA1RHW21GAfdVDRuQ7XtdYc=,tag:SYmzv26GbE1kwleXyKLG4Q==,type:str]
-tailscale_authkey: ENC[AES256_GCM,data:t8oKG+oSZrGF1Xb2YX7qWxo/z/dfsq/56kah/cvIdfQihuOSWNuMEWDcph1wlRCgRmNhQE8oqbO61m8xNQuOn+bNHsAEmh9GO9dt+uFuRKdwXJ2vM0nA+Q==,iv:6aq6buNvJ+Y0AUWBLNCdsl+svGGlXzpn5J3Oy7dPDys=,tag:T/lwzHUtyvcbjbKbu6jWeA==,type:str]
+tailscale_authkey: ENC[AES256_GCM,data:0Rkz9igafuEwHFDNqCaT6bVgL4pF7uyW4PKqimONMfZy4zrrHBO9SFedyrOjmByZxQjmHsb9VmBiHsrStPVnPmMRqZJG5lyuiWjorHcyoG+NxpAo6Az87Q==,iv:UnSWVQOFc/nEbJs5s4rF+F9XYRY0VVpIxoMp+VqKh/o=,tag:Gv6f+s+zwY2jU7NZUx0rrA==,type:str]
 headplane_cookie_secret: ENC[AES256_GCM,data:oXYRG4z16u6HS7zXoWrV2q/HL2o24n4UwVXnQvqBmbY=,iv:itAiy/w6ue4VzqO5xYnvSYN3uCLLmu52dvAAxZ2pCGc=,tag:MEFP171GpSQpAqUFsWY+VA==,type:str]
 headplane_oidc_client_secret: ENC[AES256_GCM,data:RiEESz1WHYH/smlJKmKFpPoF5HRYp8gHJoKqc49xRRuU9WnQCnmETie/68u37sSVniQmQZSOmXxdmvuuJgP5LMcPdkrQmQE+QX80RQhtTVvg2AhqRaK4V+qfQleD/aJjoIHojeM3UBUi4kYOhDJF0FFTP+qR4oitH6W8/2jxRsc=,iv:hXquOglPhRv+QTVRw5fkY7BWuwLtJxK5tNERGBOOmt8=,tag:2KczveRWoq7iTOdwjO+AUw==,type:str]
 headplane_headscale_api_key: ENC[AES256_GCM,data:KcwcprV100wfAkn+YM4+1oTfXkmyeAMAbXNpQKf2iIq0VxwqVep+fORrKmHiwDViciDoyxdMiT4scGlmd4vQRsWEHdDpkuH7MRHYu0hQepE3rSSQAMbK,iv:NEhmi2hiOE+uSIRZ4uXOK1UGpN+FQx/NpooWzTgwik8=,tag:KcPsD4gp51ERaFwgfA0BrQ==,type:str]
+headscale_oidc_client_secret: ENC[AES256_GCM,data:262lZGgtmuXTuk3He1WyqyjcXrdnIiwNyWlXEYCGKYbKkWe0JPbUdWcwGVlZ+wXt71pzKuRDpZjgdibVTWYd71mohD/Ni6CwJm7dhf517DqznnYrxojZaSxRYXg/sCVSkwEvVseJ5z2yf/Led1VLNd3I1PaUIlwkdm2P91ps7mM=,iv:w/hu7siWwNAIw7g14bake5BP8ouA/b1SZdeukZXa/dw=,tag:vAXqWfSHwIdGAjR78gSpRg==,type:str]
 caddy_acme_email: ENC[AES256_GCM,data:j+iPz4lt0Gqs2SKHTS53,iv:DQNfcpYy2v93sKeCvXzLOoBhAo0PjZrxHgFD1oVqYu8=,tag:1yPH/2cW/IiRi9lT8dELEg==,type:str]
 sops:
     age:
@@ -27,7 +28,7 @@ sops:
             Wptkf76aP9UpjhgNkxzedRebQPB7ti+UiVqCvLVimtuHcsm/NJPcRg==
             -----END AGE ENCRYPTED FILE-----
           recipient: age1hp72xyx2cnd05937e4eww95g5kdtn0wsf9j2nypw330pa69gfdxqn0lpkp
-    lastmodified: "2026-07-20T08:15:48Z"
+    lastmodified: "2026-07-20T18:41:45Z"
-    mac: ENC[AES256_GCM,data:yDiCTDaIwMCXZfzE4khI7AHNoYi3AHFX+nSXtioNRqLEOu1fBCA3OqHpzTi4Cskv2o7r9nlxx5AGPM+2d3bSHkXW7SJk680IMA/XzfDIKGU6A7+3NDt14/PgxOvPeVTfNWwlWIW9tXPtTVJmnoItTzPsxcLO3OyfbbO+vZhj/j4=,iv:xeqYTLjG0B6yCWoke0lulHetVNlShmw7Nm+8mmwOZ5I=,tag:JUEqRfEprzGMGoGsXp9rKQ==,type:str]
+    mac: ENC[AES256_GCM,data:Ie+xvOMKI4ARsYEvKc9iKuCahNQWWmjHQ56NpGsPbYF7XMv2HoOor/Nj7VJNhUD8DnoSq5A67qglfmTSk+KB65yMVSeDYJam5hwUzuo+IB9fHC1sWPNiWCVuG1iKh7ruiTaW/r3uA59+vQ2Ww5fFM/tTIuR1wtYtzVJ+5GKB/fA=,iv:5oYnhxlRfUDaxgR0FXPwE1eBrpqh/1eRWKTG8B+BgmQ=,tag:28Kxp4lp6F/mxTNXCCW8ZQ==,type:str]
     unencrypted_suffix: _unencrypted
     version: 3.13.1

services/vpn/headscale.nix

@@ -1,4 +1,4 @@
-{ ... }:
+{ config, ... }:
 
 # Headscale — self-hosted control server for the tailnet. Every host's
 # services/vpn/tailscale.nix points --login-server at https://vpn.mgaction.town
@@ -19,6 +19,39 @@
       dns = {
         base_domain = "hosts.mgaction.town";
         nameservers.global = [ "1.1.1.1" "9.9.9.9" ];
+
+        # Leave each client's own resolvers alone; only route base_domain to
+        # MagicDNS. Upstream defaults this to true, which replaces resolv.conf
+        # with 100.100.100.100 on every node — that silently breaks the LAN's
+        # `.sol` names (pihole on mercury serves those, and the global
+        # nameservers above return NXDOMAIN for them) and takes ad blocking
+        # with it. It also makes a node's entire DNS depend on tailscaled
+        # being up, which is what forced --accept-dns=false onto neptun and
+        # mercury individually.
+        override_local_dns = false;
+      };
+
+      # Authentik as the login provider, so `tailscale up --login-server ...`
+      # sends you to a browser instead of needing a pre-auth key. This is a
+      # SEPARATE Authentik application from headplane's — its own provider,
+      # slug `headscale`, redirect https://vpn.mgaction.town/oidc/callback
+      # (headscale's own callback; headplane's is under /admin).
+      #
+      # ⚠️  headscale performs OIDC discovery at STARTUP and a failure is
+      # FATAL ("creating OIDC provider from issuer config: 404 Not Found") —
+      # it will not boot, taking the whole tailnet's control plane with it.
+      # Never point `issuer` at an application that doesn't exist yet; verify
+      # with:
+      #   curl -s <issuer>.well-known/openid-configuration
+      #
+      # Headless hosts still enrol with pre-auth keys. Note also that users
+      # created here are distinct from `headscale users create` ones: matching
+      # is by the OIDC `sub` claim against the user's providerId, and 0.28
+      # dropped map_legacy_users, so CLI-made users never gain one.
+      oidc = {
+        issuer = "https://auth.mgaction.town/application/o/headscale/";
+        client_id = "14vhRYaLiONHmI2YFIxbQEveJDLu5cCvzSkTb9oq";
+        client_secret_path = config.sops.secrets.headscale_oidc_client_secret.path;
       };
 
       # Run our own DERP relay instead of pulling Tailscale's map.