diff --git a/plugins/identity-backend/src/adapters/StaticJsonAdapter.ts b/plugins/identity-backend/src/adapters/StaticJsonAdapter.ts
index a88e561ee6..cd2a40ea78 100644
--- a/plugins/identity-backend/src/adapters/StaticJsonAdapter.ts
+++ b/plugins/identity-backend/src/adapters/StaticJsonAdapter.ts
@@ -14,14 +14,19 @@
  * limitations under the License.
  */
 
-import { Group, GroupsJson, GroupsResponse, IdentityApiAdapter } from './types';
+import {
+  Group,
+  GroupsJson,
+  GroupsResponse,
+  IdentityApi,
+  GroupsRequest,
+} from './types';
 import fs from 'fs-extra';
-import express from 'express';
 import path from 'path';
 
 const GROUPS_JSON_FILE = path.join(__dirname, 'data', 'userGroups.json');
 
-export class StaticJsonAdapter implements IdentityApiAdapter {
+export class StaticJsonAdapter implements IdentityApi {
   private readonly groups: Group[];
 
   constructor() {
@@ -31,16 +36,13 @@ export class StaticJsonAdapter implements IdentityApiAdapter {
     this.groups = groupsJson.groups;
   }
 
-  getUserGroups(
-    req: express.Request,
-    res: express.Response,
-  ): express.Response<GroupsResponse> {
-    const user = req.params.user;
-    const type = req.query.type?.toString() ?? '';
-
-    const userGroups = this._getUserGroups(this.groups, user);
-    const groups = this.filterGroupsByType(userGroups, type);
-    return res.json({ groups });
+  getUserGroups(req: GroupsRequest): Promise<GroupsResponse> {
+    return new Promise(resolve => {
+      const { user, type } = req;
+      const userGroups = this._getUserGroups(this.groups, user);
+      const groups = this.filterGroupsByType(userGroups, type);
+      resolve({ groups });
+    });
   }
 
   _getUserGroups(groups: Group[], user: string) {
diff --git a/plugins/identity-backend/src/adapters/types.ts b/plugins/identity-backend/src/adapters/types.ts
index 85719205f8..59fd1324d1 100644
--- a/plugins/identity-backend/src/adapters/types.ts
+++ b/plugins/identity-backend/src/adapters/types.ts
@@ -14,8 +14,6 @@
  * limitations under the License.
  */
 
-import express from 'express';
-
 export type User = {
   name: string;
 };
@@ -35,9 +33,10 @@ export type GroupsResponse = {
   groups: Group[];
 };
 
-export interface IdentityApiAdapter {
-  getUserGroups(
-    req: express.Request,
-    res: express.Response,
-  ): express.Response<GroupsResponse>;
+export type GroupsRequest = {
+  user: string;
+  type: string;
+};
+export interface IdentityApi {
+  getUserGroups(req: GroupsRequest): Promise<GroupsResponse>;
 }
diff --git a/plugins/identity-backend/src/service/router.ts b/plugins/identity-backend/src/service/router.ts
index ac6267ba75..256ef6ce3c 100644
--- a/plugins/identity-backend/src/service/router.ts
+++ b/plugins/identity-backend/src/service/router.ts
@@ -18,15 +18,21 @@ import express from 'express';
 import Router from 'express-promise-router';
 import { Logger } from 'winston';
 import { StaticJsonAdapter } from '../adapters';
-import { IdentityApiAdapter } from '../adapters/types';
+import { IdentityApi } from '../adapters/types';
 
 export interface RouterOptions {
   logger: Logger;
 }
 
-const makeRouter = (adapter: IdentityApiAdapter): express.Router => {
+const makeRouter = (adapter: IdentityApi): express.Router => {
   const router = Router();
-  router.get('/users/:user/groups', adapter.getUserGroups.bind(adapter));
+  router.get('/users/:user/groups', async (req, res) => {
+    const user = req.params.user;
+    const type = req.query.type?.toString() ?? '';
+
+    const response = await adapter.getUserGroups({ user, type });
+    res.send(response);
+  });
   return router;
 };
 
@@ -35,7 +41,7 @@ export async function createRouter(
 ): Promise<express.Router> {
   const logger = options.logger;
 
-  logger.info('Initializing identity provider');
+  logger.info('Initializing identity API backend');
   const adapter = new StaticJsonAdapter();
   return makeRouter(adapter);
 }