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Merge pull request 'C1: pin ringtail wired IP to 192.168.1.21 (static)' (#355) from ringtail-static-ip into main

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Erich Blume 2026-05-12 09:59:59 -07:00
commit bc8ceb502b
3 changed files with 33 additions and 1 deletions
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docs/changelog.d/ringtail-static-ip.infra.md Normal file
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Pin ringtail's wired IP to `192.168.1.21` via NixOS scripted networking; NetworkManager no longer manages `enp5s0`. Removes DHCP lease renewal as a failure mode after a silent lease teardown took ringtail offline. Also explicitly enables `net.ipv4.ip_forward` (previously set implicitly by scripted-DHCP) so k3s pod networking and Tailscale routing continue to work with static networking.

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docs/reference/infrastructure/ringtail.md
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@ -25,6 +25,19 @@ Service host and gaming PC. Custom-built PC running NixOS.
| **OS** | NixOS 25.11 (Sway/Wayland) |
| **Tailscale hostname** | `ringtail.tail8d86e.ts.net` |
## Networking
| Property | Value |
|----------|-------|
| **Interface (wired)** | `enp5s0` |
| **IP** | `192.168.1.21/24` (static, set by NixOS scripted networking) |
| **Gateway** | `192.168.1.1` (UX7) |
| **DNS** | `192.168.1.1`, `1.1.1.1` (used as Tailscale's upstream resolvers; `/etc/resolv.conf` is owned by Tailscale's MagicDNS at `100.100.100.100`) |
| **DHCP reservation** | UniFi "Fixed IP" tied to ringtail's MAC; belt-and-suspenders so the UX7 won't lease `192.168.1.21` to anyone else even though ringtail no longer asks for it |
| **Wireless** | `wlp6s0` still managed by NetworkManager as a fallback path |
NetworkManager is enabled but explicitly excluded from managing `enp5s0` via `networking.networkmanager.unmanaged = [ "interface-name:enp5s0" ]`. The wired address is configured by a deterministic `network-addresses-enp5s0.service` oneshot — no daemon, no lease, no renewal.
## Software
Managed declaratively via `nixos/ringtail/configuration.nix`. Home-manager handles ringtail-specific sway/waybar config; chezmoi manages cross-platform dotfiles.

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nixos/ringtail/configuration.nix
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@ -16,8 +16,26 @@ in
systemd.tpm2.enable = false;
# Networking
# Wired interface (enp5s0) uses a static IP configured by NixOS scripted
# networking; NetworkManager is left enabled for the wireless fallback only.
networking.hostName = "ringtail";
networking.networkmanager.enable = true;
networking.networkmanager = {
enable = true;
unmanaged = [ "interface-name:enp5s0" ];
};
networking.useDHCP = false;
networking.interfaces.enp5s0.ipv4.addresses = [{
address = "192.168.1.21";
prefixLength = 24;
}];
networking.defaultGateway = "192.168.1.1";
networking.nameservers = [ "192.168.1.1" "1.1.1.1" ];
# K3s pod networking and Tailscale tunnel routing require IP forwarding.
# NixOS leaves this off by default; previously it was being enabled
# implicitly by NM/scripted-DHCP setup, but with static networking we
# have to set it explicitly.
boot.kernel.sysctl."net.ipv4.ip_forward" = 1;
# Time zone
time.timeZone = "America/Los_Angeles";