Bump clan-core and nixos-mailserver to 26.05 (NixOS 26.05) and adapt to
the breaking changes surfaced by nix flake check:
- mesh-hosts/clan.nix: read the new shared, instance-scoped zerotier vars
(zerotier-ip-<machine>-zerotier, zerotier-network-zerotier); admit
external members via the controller's native allowedIds.
- monitoring/server.nix: Grafana lost its built-in secret_key default;
mint one via a clan generator and pass it with $__file{}.
- dns/authoritative.nix: services.resolved.extraConfig removed -> settings.
- mail.nix: SNM cert API change (x509.useACMEHost + acme extraDomainNames)
and accounts/dkim option renames.
- docs: mesh runbook updated for the new var paths and allowedIds.
mx1 runs Simple NixOS Mailserver (Postfix/Dovecot/Rspamd/OpenDKIM) for
cnx.email. The TLS cert is obtained via ACME DNS-01 using a dedicated,
scoped TSIG key (acme_mx1) that ns1 authorizes for only
_acme-challenge.mx1 and _acme-challenge.mta-sts on the cnx.email zone, so
the credential can write nothing else. Mailbox passwords are auto-minted
by a clan vars generator (four-word passphrase + number).
DANE TLSA (3 1 1) is published for _25._tcp.mx1; --reuse-key keeps the
key digest stable across renewals. MTA-STS is enforced via a Caddy vhost
serving the policy on :443 from the same cert (mta-sts SAN). Firewall
opens 25/587/465/143/993/443; 80 stays closed.
kurogeek
Berwn