Merge pull request 'Add global DNS search domain to fix NFS mounts on lxc-docker' (#23) from worktree-fix-container-dns-search-domain into main

Reviewed-on: #23

modules/common/configuration.nix

@@ -13,6 +13,24 @@
 
   networking.networkmanager.enable = true; # Easiest to use and most distros use this by default.
 
+  # No host declares a DNS search domain anywhere else, and cross-host
+  # references throughout this repo (vars.nfsServerHost, vars.nixCacheHost,
+  # vars.dockerHost, ...) are bare short names, not FQDNs -- resolving them
+  # depends entirely on whatever network stack happens to be in play
+  # picking up the DHCP-advertised domain as a search suffix. NetworkManager
+  # does that by default, which is why this went unnoticed on
+  # NetworkManager-managed hosts, but LXC containers (modules/platforms/lxc.nix
+  # force-disables NetworkManager and Proxmox writes their systemd-networkd
+  # config itself) never get one. Confirmed live on lxc-docker: systemd-resolved
+  # had no search domain for eth0, "server" failed to resolve
+  # ("Name or service not known") while "server.sweet.home" resolved fine via
+  # the same DNS server, so every NFS mount in modules/docker/mount-data.nix
+  # failed even after fixing the automount/mount=nfs bugs. This applies the
+  # search domain globally via systemd-resolved's own config rather than the
+  # per-link DHCP path, so it isn't at the mercy of whichever component owns
+  # a given host's interface file.
+  networking.search = [ vars.homeDomain ];
+
   # Recommended over the true default (bypasses ZFS's own import safeguards)
   # per the option's own docs; matches hosts/docker/host.nix and
   # modules/services/zfs/enable-service.nix, which already set this