user_group_admin — User-Managed Groups

Let users create and manage their own Nextcloud groups, with optional storage grants allocated to members.

Author: Frederik Orellana, Technical University of Denmark (fror@dtu.dk) — developed for the ScienceData cloud platform.
License: AGPL-3.0

Overview

user_group_admin extends Nextcloud's group system so ordinary users can:

• Create groups and invite members (invite/accept workflow)
• Allow open-join groups (no invite required)
• Keep private groups (hidden from non-members)
• Allocate a storage grant from their own quota to the group — usage consumed by the grant is billed to the group owner, not the members
• Cross-silo sync: group membership changes are propagated to all registered silos via the files_sharding internal API

In a ScienceData sharded deployment the master holds the authoritative group registry; silo nodes mirror it so that group membership is available locally for DAV and sharing operations.

Requirements

• Nextcloud 34+
• PHP 8.2+
• Node.js 18+ and webpack (for frontend build)
• files_sharding (optional) — required for cross-silo group sync

Installation

occ app:enable user_group_admin

Migrations run automatically and create two tables:

• user_group_admin_groups — group metadata (name, owner, type, storage grant)
• user_group_admin_members — member roster with invitation state

Features

Invite workflow

Group owners invite users by username. Invited users see a pending invitation in their interface and can accept or decline. Accepted memberships are immediately synced to all silos.

Open-join groups

When a group is set to open-join, any user can join without an invitation. The owner can still remove members.

Private groups

Private groups are not visible to non-members in search or group listings.

Storage grant

A group owner can allocate a fixed storage amount (e.g. 10 GB) to the group. Members of the group can use storage up to that grant without it counting against their own free quota. The consumed storage is billed to the group owner by files_accounting.

The grant is configured in the group's Settings tab:

Storage grant — Allocate storage from your own quota to group members.
Amount: [dropdown: None / 1 GB / 5 GB / 10 GB / 50 GB / 100 GB / 500 GB / 1 TB]

Cross-silo sync

When a group is created, updated, or deleted on the master, files_sharding propagates the change to all registered silos via POST /internal/users/{userId}/update and related endpoints. Silos store a local mirror so group membership is available without a round-trip to the master.

Architecture

Custom group backend

user_group_admin registers a custom IGroupBackend with Nextcloud. Groups whose names match the app's prefix are resolved through this backend rather than the default database backend. The backend reads from user_group_admin_groups and user_group_admin_members.

DB schema

user_group_admin_groups

Column	Type	Description
id	int (PK)	Auto-increment
gid	varchar	Group identifier
owner	varchar	User ID of group owner
type	varchar	invite / open / private
storage_grant	bigint	Grant size in bytes (0 = none)

user_group_admin_members

Column	Type	Description
id	int (PK)	Auto-increment
gid	varchar	Group identifier
uid	varchar	Member user ID
state	varchar	invited / member

Sharding adapter

When files_sharding is present, write operations (create group, add member, remove member, delete group) are wrapped to also POST to each registered silo's internal API so the mirror stays current.

OCS API

All endpoints under /ocs/v2.php/apps/user_group_admin/api/v1/. Authentication via Nextcloud session or admin token.

Method	URL	Description
GET	/groups	List groups (owner or member)
POST	/groups	Create group
DELETE	/groups/{gid}	Delete group (owner only)
GET	/groups/{gid}/members	List members
POST	/groups/{gid}/members	Invite or add member
DELETE	/groups/{gid}/members/{uid}	Remove member
POST	/groups/{gid}/accept	Accept invitation
PUT	/groups/{gid}	Update group settings (type, storage grant)

Build

The frontend (Vue 2) must be built with webpack via build/frontend-legacy. The app's entry point is registered in build/frontend-legacy/webpack.modules.cjs:

user_group_admin: {
    main: path.join(__dirname, 'apps/user_group_admin/src', 'main.js'),
},

A symlink must exist at build/frontend-legacy/apps/user_group_admin → ../../apps/user_group_admin.

Always do a full webpack build (no MODULE= flag) to avoid splitChunks producing oversized bundles with wrong initialisation order:

cd /home/claude/code/nextcloud/build/frontend-legacy
node node_modules/webpack/bin/webpack.js --node-env production

Copy the built bundle into the app:

mkdir -p /home/claude/code/nextcloud/apps/user_group_admin/js
cp /home/claude/code/nextcloud/dist/user_group_admin-main.js* \
   /home/claude/code/nextcloud/apps/user_group_admin/js/
# Fix source map reference
sed -i 's|sourceMappingURL=user_group_admin-main.js.map|sourceMappingURL=main.js.map|' \
   /home/claude/code/nextcloud/apps/user_group_admin/js/main.js

Deployment

# Master
rsync -av --delete apps/user_group_admin/ master:/var/www/nextcloud/apps/user_group_admin/

# Silo1
rsync -av --delete apps/user_group_admin/ silo1:/var/www/nextcloud/apps/user_group_admin/

# Silo2
rsync -av --delete apps/user_group_admin/ silo2:/var/www/nextcloud/apps/user_group_admin/

# Enable on each node (runs migrations automatically)
occ app:enable user_group_admin

After deploying JavaScript changes, reload PHP-FPM to clear OPcache:

service php8.3-fpm reload