use GitLab group members REST API

Signed-off-by: Matteo Silvestri <matteosilv@gmail.com>

.changeset/flat-rules-rush.md

@@ -2,6 +2,13 @@
 '@backstage/plugin-catalog-backend-module-gitlab': patch
 ---
 
-fix: use publicEmail in GitLab client
+fix: use REST API to get root group memberships for GitLab SaaS users listing
 
-client was using commitEmail that is visible only for self-managed GitLab admins. publicEmail is visible, but only if the user explicitly enable the corresponding setting on GitLab.
+This API is the only one that shows `email` field for enterprise users and
+allows to filter out bot users not using a license using the `is_using_seat`
+field.
+
+ref:
+
+https://docs.gitlab.com/ee/user/enterprise_user/#get-users-email-addresses-through-the-api
+https://docs.gitlab.com/ee/api/members.html#limitations

plugins/catalog-backend-module-gitlab/src/lib/client.ts

@@ -91,6 +91,22 @@ export class GitLabClient {
     });
   }
 
+  async listSaaSUsers(
+    groupPath: string,
+    options?: CommonListOptions,
+  ): Promise<PagedResponse<GitLabUser>> {
+    return this.pagedRequest(
+      `/groups/${encodeURIComponent(groupPath)}/members`,
+      {
+        ...options,
+        show_seat_info: true,
+      },
+    ).then(resp => {
+      resp.items = resp.items.filter(user => user.is_using_seat);
+      return resp;
+    });
+  }
+
   async listGroups(
     options?: CommonListOptions,
   ): Promise<PagedResponse<GitLabGroup>> {

plugins/catalog-backend-module-gitlab/src/providers/GitlabOrgDiscoveryEntityProvider.ts

@@ -190,12 +190,14 @@ export class GitlabOrgDiscoveryEntityProvider implements EntityProvider {
       });
     } else {
       groups = (await client.listDescendantGroups(this.config.group)).items;
-      users = (
-        await client.getGroupMembers(this.config.group.split('/')[0], [
-          'DIRECT',
-          'DESCENDANTS',
-        ])
-      ).items;
+      const rootGroup = this.config.group.split('/')[0];
+      users = paginated<GitLabUser>(
+        options => client.listSaaSUsers(rootGroup, options),
+        {
+          page: 1,
+          per_page: 100,
+        },
+      );
     }
 
     const idMappedUser: { [userId: number]: GitLabUser } = {};