Step 1: an invariant that holds of any raised scenario

The address collision was found by eye. This is the mechanical form of it: no two machines hold one address on one segment. Pure over already-collected facts, so the logic is tested without a hypervisor — including the cases that would make it useless if got wrong: the same address on DIFFERENT segments is normal and must not be reported, and one machine holding an address twice is not two machines. Asserted against whatever the integration suite has standing, read from the hypervisor rather than from the declaration. The declaration is what was accepted, and it was accepted.
2026-08-25 00:21:09 +02:00
parent a6b7d67e19
commit 715f367147
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+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { duplicateAddresses, describeConflicts } from "../src/lifecycle/invariants.ts";
+
+/**
+ * The fault this defends against, in the shape it actually occurred: two gateways declared
+ * with the same public address became two router containers, both holding it on one segment.
+ */
+
+test("two machines holding one address on one segment is a conflict", () => {
+  const conflicts = duplicateAddresses([
+    { machine: "gw-home", segment: "isp-home", address: "198.51.100.7/24" },
+    { machine: "gw-devices", segment: "isp-home", address: "198.51.100.7/24" },
+    { machine: "transit", segment: "isp-home", address: "198.51.100.254/24" },
+  ]);
+  assert.equal(conflicts.length, 1);
+  assert.equal(conflicts[0]?.address, "198.51.100.7");
+  assert.deepEqual(conflicts[0]?.machines, ["gw-devices", "gw-home"]);
+  assert.match(describeConflicts(conflicts), /198\.51\.100\.7 is held by gw-devices and gw-home/);
+});
+
+test("the same address on different segments is NOT a conflict", () => {
+  // Every private network has its own `.1`. Reporting that would make the check useless.
+  assert.deepEqual(
+    duplicateAddresses([
+      { machine: "gw-a", segment: "home", address: "192.168.1.1/24" },
+      { machine: "gw-b", segment: "cafe", address: "192.168.1.1/24" },
+    ]),
+    [],
+  );
+});
+
+test("one machine holding an address twice is not two machines", () => {
+  // A machine multi-homed onto the same segment, or an address read back from two places.
+  assert.deepEqual(
+    duplicateAddresses([
+      { machine: "gw", segment: "isp", address: "198.51.100.7/24" },
+      { machine: "gw", segment: "isp", address: "198.51.100.7" },
+    ]),
+    [],
+  );
+});
+
+test("the prefix length is not part of the address", () => {
+  // The same address declared /24 in one place and /16 in another is still one address.
+  const conflicts = duplicateAddresses([
+    { machine: "a", segment: "isp", address: "198.51.100.7/24" },
+    { machine: "b", segment: "isp", address: "198.51.100.7/16" },
+  ]);
+  assert.equal(conflicts.length, 1);
+});
+
+test("both families are checked", () => {
+  const conflicts = duplicateAddresses([
+    { machine: "a", segment: "isp", address: "2001:db8:b::7/48" },
+    { machine: "b", segment: "isp", address: "2001:db8:b::7/48" },
+  ]);
+  assert.equal(conflicts.length, 1);
+  assert.equal(conflicts[0]?.address, "2001:db8:b::7");
+});