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C1: pin ringtail wired IP to 192.168.1.21 (static)

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Removes DHCP lease renewal as a failure mode on ringtail after an outage
on 2026-05-12 where the IP and routes silently disappeared from enp5s0
without any kernel link event. NetworkManager stays enabled for wireless
fallback but no longer manages the wired interface.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Erich Blume 2026-05-12 09:33:57 -07:00
commit d0b5423135
3 changed files with 27 additions and 1 deletions
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1
docs/changelog.d/ringtail-static-ip.infra.md Normal file
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@ -0,0 +1 @@
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.

13
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) | | **OS** | NixOS 25.11 (Sway/Wayland) |
| **Tailscale hostname** | `ringtail.tail8d86e.ts.net` | | **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 ## Software
Managed declaratively via `nixos/ringtail/configuration.nix`. Home-manager handles ringtail-specific sway/waybar config; chezmoi manages cross-platform dotfiles. Managed declaratively via `nixos/ringtail/configuration.nix`. Home-manager handles ringtail-specific sway/waybar config; chezmoi manages cross-platform dotfiles.

14
nixos/ringtail/configuration.nix
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@ -16,8 +16,20 @@ in
systemd.tpm2.enable = false; systemd.tpm2.enable = false;
# Networking # 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.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" ];
# Time zone # Time zone
time.timeZone = "America/Los_Angeles"; time.timeZone = "America/Los_Angeles";