fix: remove empty routers/services traefik config instead of writing invalid yaml

Attaching Basic Auth or a Redirect to an application with no domains
wrote an empty routers/services block to the app's dynamic config
file. Traefik's file provider rejects that as invalid and aborts its
watcher, blocking config updates for every other application.

Fixes #5189

apps/dokploy/__test__/traefik/write-app-traefik-config.test.ts

@@ -0,0 +1,104 @@
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { writeAppTraefikConfig } from "@dokploy/server/utils/traefik/application";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+const mocks = vi.hoisted(() => ({
+	execAsyncRemote: vi.fn(),
+}));
+
+vi.mock("@dokploy/server/utils/process/execAsync", async (importOriginal) => {
+	const actual =
+		await importOriginal<typeof import("@dokploy/server/utils/process/execAsync")>();
+	return {
+		...actual,
+		execAsyncRemote: mocks.execAsyncRemote,
+	};
+});
+
+describe("writeAppTraefikConfig", () => {
+	let cwd: string;
+	let dynamicPath: string;
+
+	beforeEach(() => {
+		cwd = fs.mkdtempSync(path.join(os.tmpdir(), "dokploy-traefik-"));
+		dynamicPath = path.join(cwd, ".docker", "traefik", "dynamic");
+		fs.mkdirSync(dynamicPath, { recursive: true });
+		vi.spyOn(process, "cwd").mockReturnValue(cwd);
+		vi.clearAllMocks();
+	});
+
+	afterEach(() => {
+		vi.restoreAllMocks();
+		fs.rmSync(cwd, { recursive: true, force: true });
+	});
+
+	// Regression test for #5189: Traefik's file provider rejects a standalone
+	// `routers: {}` / `services: {}` map and aborts its watcher for every
+	// dynamic config once it hits one, so an app with no domains must never
+	// get an on-disk config file at all.
+	it("removes the file instead of writing empty routers/services", async () => {
+		const appName = "no-domain-app";
+		const configPath = path.join(dynamicPath, `${appName}.yml`);
+		fs.writeFileSync(configPath, "stale content", "utf8");
+
+		await writeAppTraefikConfig(
+			{ http: { routers: {}, services: {} } },
+			appName,
+		);
+
+		expect(fs.existsSync(configPath)).toBe(false);
+	});
+
+	it("writes the file when routers/services are present", async () => {
+		const appName = "with-domain-app";
+		const configPath = path.join(dynamicPath, `${appName}.yml`);
+
+		await writeAppTraefikConfig(
+			{
+				http: {
+					routers: { [`${appName}-router-1`]: { rule: "Host(`x`)" } },
+					services: {},
+				},
+			},
+			appName,
+		);
+
+		expect(fs.existsSync(configPath)).toBe(true);
+	});
+
+	it("removes the remote file instead of writing empty routers/services", async () => {
+		mocks.execAsyncRemote.mockResolvedValue({ stdout: "", stderr: "" });
+
+		await writeAppTraefikConfig(
+			{ http: { routers: {}, services: {} } },
+			"no-domain-app",
+			"server-id",
+		);
+
+		expect(mocks.execAsyncRemote).toHaveBeenCalledOnce();
+		const [, command] = mocks.execAsyncRemote.mock.calls[0];
+		expect(command).toMatch(/^rm -f /);
+		expect(command).toContain("no-domain-app.yml");
+	});
+
+	it("writes the remote file when routers/services are present", async () => {
+		mocks.execAsyncRemote.mockResolvedValue({ stdout: "", stderr: "" });
+
+		await writeAppTraefikConfig(
+			{
+				http: {
+					routers: { "with-domain-app-router-1": { rule: "Host(`x`)" } },
+					services: {},
+				},
+			},
+			"with-domain-app",
+			"server-id",
+		);
+
+		expect(mocks.execAsyncRemote).toHaveBeenCalledOnce();
+		const [, command] = mocks.execAsyncRemote.mock.calls[0];
+		expect(command).toMatch(/^echo /);
+	});
+});