From dbcfb41bd025a9a05423ac278851706623192800 Mon Sep 17 00:00:00 2001
From: Morgan Helton <mhelton@gmail.com>
Date: Sun, 30 Aug 2026 11:18:01 -0500
Subject: [PATCH] feat(chopper): add an echoip microvm guest

echoip is trivial enough that it makes plain whether a guest booted and
reached the network, which makes it a reasonable first VM on the host
support added previously.

It takes a static address from below the DHCP pool, so Kea has nothing to
hand out, and a vsock CID of 3. Everything else comes from common.nix.
---
 hosts/chopper/microvm/default.nix |  1 +
 hosts/chopper/microvm/echoip.nix  | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 hosts/chopper/microvm/echoip.nix

diff --git a/hosts/chopper/microvm/default.nix b/hosts/chopper/microvm/default.nix
index cc4934c..bcf855c 100644
--- a/hosts/chopper/microvm/default.nix
+++ b/hosts/chopper/microvm/default.nix
@@ -2,6 +2,7 @@
 {
   imports = [
     inputs.microvm.nixosModules.host
+    ./echoip.nix
   ];
 
   users.users.microvm.extraGroups = [ "tailscale-key" ];
diff --git a/hosts/chopper/microvm/echoip.nix b/hosts/chopper/microvm/echoip.nix
new file mode 100644
index 0000000..253a954
--- /dev/null
+++ b/hosts/chopper/microvm/echoip.nix
@@ -0,0 +1,25 @@
+{ ... }:
+{
+  microvm.vms.echoip = {
+    extraModules = [ ./common.nix ];
+    config = {
+      microvm = {
+        vcpu = 1;
+        mem = 512;
+        vsock.cid = 3;
+        interfaces = [
+          {
+            type = "tap";
+            id = "vm-echoip";
+            mac = "02:00:00:00:20:01";
+          }
+        ];
+      };
+
+      systemd.network.networks."20-lan".address = [ "192.168.20.50/23" ];
+
+      services.echoip.enable = true;
+      networking.firewall.allowedTCPPorts = [ 8080 ];
+    };
+  };
+}