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

packages/server/src/utils/traefik/application.ts

@@ -292,6 +292,26 @@ export const writeTraefikConfigRemote = async (
 	}
 };
 
+const isEmptyHttpRoutersAndServices = (traefikConfig: FileConfig) =>
+	Object.keys(traefikConfig.http?.routers || {}).length === 0 &&
+	Object.keys(traefikConfig.http?.services || {}).length === 0;
+
+export const writeAppTraefikConfig = async (
+	traefikConfig: FileConfig,
+	appName: string,
+	serverId?: string | null,
+) => {
+	if (isEmptyHttpRoutersAndServices(traefikConfig)) {
+		await removeTraefikConfig(appName, serverId);
+		return;
+	}
+	if (serverId) {
+		await writeTraefikConfigRemote(traefikConfig, appName, serverId);
+	} else {
+		writeTraefikConfig(traefikConfig, appName);
+	}
+};
+
 export const createServiceConfig = (
 	appName: string,
 	domain: Domain,

packages/server/src/utils/traefik/redirect.ts

@@ -3,7 +3,7 @@ import type { ApplicationNested } from "../builders";
 import {
 	loadOrCreateConfig,
 	loadOrCreateConfigRemote,
-	writeTraefikConfig,
+	writeAppTraefikConfig,
 	writeTraefikConfigRemote,
 } from "./application";
 import type { FileConfig } from "./file-types";
@@ -89,11 +89,10 @@ export const createRedirectMiddleware = async (
 
 	if (serverId) {
 		await writeTraefikConfigRemote(config, "middlewares", serverId);
-		await writeTraefikConfigRemote(appConfig, appName, serverId);
 	} else {
 		writeMiddleware(config);
-		writeTraefikConfig(appConfig, appName);
 	}
+	await writeAppTraefikConfig(appConfig, appName, serverId);
 };
 
 export const removeRedirectMiddleware = async (
@@ -124,9 +123,8 @@ export const removeRedirectMiddleware = async (
 
 	if (serverId) {
 		await writeTraefikConfigRemote(config, "middlewares", serverId);
-		await writeTraefikConfigRemote(appConfig, appName, serverId);
 	} else {
-		writeTraefikConfig(appConfig, appName);
 		writeMiddleware(config);
 	}
+	await writeAppTraefikConfig(appConfig, appName, serverId);
 };

packages/server/src/utils/traefik/security.ts

@@ -4,7 +4,7 @@ import type { ApplicationNested } from "../builders";
 import {
 	loadOrCreateConfig,
 	loadOrCreateConfigRemote,
-	writeTraefikConfig,
+	writeAppTraefikConfig,
 	writeTraefikConfigRemote,
 } from "./application";
 import type {
@@ -62,11 +62,10 @@ export const createSecurityMiddleware = async (
 	addMiddleware(appConfig, middlewareName);
 	if (serverId) {
 		await writeTraefikConfigRemote(config, "middlewares", serverId);
-		await writeTraefikConfigRemote(appConfig, appName, serverId);
 	} else {
-		writeTraefikConfig(appConfig, appName);
 		writeMiddleware(config);
 	}
+	await writeAppTraefikConfig(appConfig, appName, serverId);
 };
 
 export const removeSecurityMiddleware = async (
@@ -89,6 +88,7 @@ export const removeSecurityMiddleware = async (
 		appConfig = loadOrCreateConfig(appName);
 	}
 	const middlewareName = `auth-${appName}`;
+	let removedLastUser = false;
 
 	if (config.http?.middlewares) {
 		const currentMiddleware = config.http.middlewares[middlewareName];
@@ -106,11 +106,7 @@ export const removeSecurityMiddleware = async (
 					delete config.http.middlewares[middlewareName];
 				}
 				deleteMiddleware(appConfig, middlewareName);
-				if (serverId) {
-					await writeTraefikConfigRemote(appConfig, appName, serverId);
-				} else {
-					writeTraefikConfig(appConfig, appName);
-				}
+				removedLastUser = true;
 			}
 		}
 	}
@@ -120,6 +116,9 @@ export const removeSecurityMiddleware = async (
 	} else {
 		writeMiddleware(config);
 	}
+	if (removedLastUser) {
+		await writeAppTraefikConfig(appConfig, appName, serverId);
+	}
 };
 
 const isBasicAuthMiddleware = (