Warn if permission backend is used without permissions enabled

Signed-off-by: Joe Porpeglia <josephp@spotify.com>

plugins/permission-backend/api-report.md

@@ -3,6 +3,7 @@
 > Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
 
 ```ts
+import { Config } from '@backstage/config';
 import express from 'express';
 import { IdentityClient } from '@backstage/plugin-auth-node';
 import { Logger as Logger_2 } from 'winston';
@@ -14,6 +15,8 @@ export function createRouter(options: RouterOptions): Promise<express.Router>;
 
 // @public
 export interface RouterOptions {
+  // (undocumented)
+  config: Config;
   // (undocumented)
   discovery: PluginEndpointDiscovery;
   // (undocumented)

plugins/permission-backend/src/service/router.test.ts

@@ -26,6 +26,7 @@ import {
 import { PermissionIntegrationClient } from './PermissionIntegrationClient';
 
 import { createRouter } from './router';
+import { ConfigReader } from '@backstage/config';
 
 const mockApplyConditions: jest.MockedFunction<
   InstanceType<typeof PermissionIntegrationClient>['applyConditions']
@@ -63,6 +64,7 @@ describe('createRouter', () => {
 
   beforeAll(async () => {
     const router = await createRouter({
+      config: new ConfigReader({ permission: { enabled: true } }),
       logger: getVoidLogger(),
       discovery: {
         getBaseUrl: jest.fn(),

plugins/permission-backend/src/service/router.ts

@@ -44,6 +44,7 @@ import {
 import { PermissionIntegrationClient } from './PermissionIntegrationClient';
 import { memoize } from 'lodash';
 import DataLoader from 'dataloader';
+import { Config } from '@backstage/config';
 
 const querySchema: z.ZodSchema<Identified<AuthorizeQuery>> = z.object({
   id: z.string(),
@@ -79,6 +80,7 @@ export interface RouterOptions {
   discovery: PluginEndpointDiscovery;
   policy: PermissionPolicy;
   identity: IdentityClient;
+  config: Config;
 }
 
 const handleRequest = async (
@@ -139,7 +141,13 @@ const handleRequest = async (
 export async function createRouter(
   options: RouterOptions,
 ): Promise<express.Router> {
-  const { policy, discovery, identity } = options;
+  const { policy, discovery, identity, config, logger } = options;
+
+  if (!config.getOptionalBoolean('permission.enabled')) {
+    logger.warn(
+      'Permission backend started with permissions disabled. Enable permissions by setting permission.enabled=true.',
+    );
+  }
 
   const permissionIntegrationClient = new PermissionIntegrationClient({
     discovery,