Address review of host pairing

Revoking a host now unassigns its instances instead of being refused
while it has any, and removes its system metrics.

Approving and revoking no longer force a save. Hosts are saved by
autosave and on exit like everything else, which also removes the
approving state from pairing requests.

The approval code and link are logged as warnings so they show up in
the systemd service, which only prints warnings and above. The pairing
limits are now the controller.host_pairing_timeout and
controller.host_pairing_max_pending config values, 0 removes the limit.

Subscribers take an optional permitted function, used for the pairing
requests instead of overrides in a subclass.

test/controller/ControlConnection.test.js

@@ -326,16 +326,9 @@ describe("controller/src/ControlConnection", function() {
 				await connection.handleHostRevokeRequest(new lib.HostRevokeRequest(hostId));
 			}
 
-			it("deletes and saves the host record", async function() {
-				let savedWithoutHost;
-				const originalSave = controller.hosts.save;
-				controller.hosts.save = async function() {
-					savedWithoutHost = !this.has(10);
-					return await originalSave.call(this);
-				};
+			it("deletes the host record", async function() {
 				await revoke();
 				assert.equal(controller.hosts.has(10), false);
-				assert.equal(savedWithoutHost, true, "hosts were not saved after deleting the record");
 				assert.deepEqual(broadcasts, [{ id: 10, isDeleted: true }]);
 				assert.equal(audits.length, 1);
 				assert.match(audits[0], /User admin revoked host host-10 \(10\)/);
@@ -356,15 +349,6 @@ describe("controller/src/ControlConnection", function() {
 				await revoke();
 				assert.equal(terminated, true);
 			});
-			it("terminates the connection of the host when saving fails", async function() {
-				let terminated = false;
-				controller.wsServer.hostConnections.set(10, { connector: { terminate() { terminated = true; } } });
-				controller.hosts.save = async () => { throw new Error("EPERM: operation not permitted"); };
-				await assert.rejects(revoke(), /EPERM/);
-				assert.equal(terminated, true, "revoked host kept its connection");
-				assert.equal(controller.hosts.has(10), false);
-				assert.equal(controller.notes.get("host/10"), undefined);
-			});
 			it("does not leave a host record behind when the connection closes", async function() {
 				const connector = new MockConnector(addr("controller"), addr({ hostId: 10 }));
 				connector.terminate = () => { connector.emit("close"); };
@@ -378,27 +362,31 @@ describe("controller/src/ControlConnection", function() {
 				assert.equal(controller.hosts.has(10), false, "host record was recreated");
 				assert.deepEqual(broadcasts.at(-1), { id: 10, isDeleted: true });
 			});
-			it("refuses to revoke a host with assigned instances", async function() {
-				controller.setNote("host", "10", "rack 3", "someone");
-				let terminated = false;
-				controller.wsServer.hostConnections.set(10, { connector: { terminate() { terminated = true; } } });
+			it("unassigns the instances of the host without waiting for it", async function() {
+				let closing = false;
+				controller.wsServer.hostConnections.set(10, {
+					connector: { terminate() { closing = true; }, get closing() { return closing; } },
+					send: () => new Promise(() => {}),
+				});
 				assignInstance(101, "alpha", 10);
 				assignInstance(102, "beta", 10);
 				assignInstance(201, "gamma", 20);
 
-				await assert.rejects(
-					revoke(),
-					new lib.ConflictError("Cannot revoke host host-10 while instances are assigned to it: alpha, beta"),
-				);
-				assert.equal(controller.hosts.get(10), record);
-				assert.equal(controller.notes.get("host/10").isDeleted, false);
-				assert.equal(terminated, false);
-				assert.deepEqual(broadcasts, []);
-			});
-			it("ignores instances assigned to other hosts", async function() {
-				assignInstance(201, "gamma", 20);
 				await revoke();
 				assert.equal(controller.hosts.has(10), false);
+				for (const id of [101, 102]) {
+					const instance = controller.instances.get(id);
+					assert.equal(instance.config.get("instance.assigned_host"), null);
+					assert.equal(instance.status, "unassigned");
+				}
+				assert.equal(controller.instances.get(201).config.get("instance.assigned_host"), 20);
+			});
+			it("removes the system metrics of the host", async function() {
+				controller.systems.set(await lib.gatherSystemInfo(10, false, false, 0));
+				controller.systems.set(await lib.gatherSystemInfo("controller", false, false, 0));
+				await revoke();
+				assert.equal(controller.systems.has(10), false);
+				assert.equal(controller.systems.has("controller"), true);
 			});
 			it("throws NotFoundError for an unknown host", async function() {
 				await assert.rejects(revoke(99), new lib.NotFoundError("Unknown host id (99)"));
@@ -421,7 +409,7 @@ describe("controller/src/ControlConnection", function() {
 				const rejected = controller.hostPairing.create("Host C", "", "10.0.0.3");
 				const pending = controller.hostPairing.create("Host D", "", "10.0.0.4");
 				controller.hostPairing._bySecret.get(expired.requestId).lastPollMs -= 60e3;
-				await controller.hostPairing.approve(approved.code, undefined, "admin");
+				controller.hostPairing.approve(approved.code, undefined, "admin");
 				controller.hostPairing.reject(rejected.code, "admin");
 
 				const list = await connection.handleHostPairingListRequest(new lib.HostPairingListRequest());
@@ -440,7 +428,7 @@ describe("controller/src/ControlConnection", function() {
 			it("rejects a request", async function() {
 				const { requestId, code } = controller.hostPairing.create("Host A", "", "10.0.0.1");
 				await connection.handleHostPairingRejectRequest(new lib.HostPairingRejectRequest(code.toLowerCase()));
-				assert.equal(controller.hostPairing.requests.has(code), false);
+				assert.equal(controller.hostPairing.records.has(code), false);
 				assert.throws(() => controller.hostPairing.poll(requestId), /Request was rejected/);
 				assert.equal(controller.hosts.size, 0);
 				assert(audits.some(msg => msg.startsWith(`User admin rejected host Host A with code ${code}`)));