the-littlest-jupyterhub/docs/howto/content/share-data.md

(howto-content-share-data)=

# Share data with your users

There are a few options for sharing data with your users, this page covers
a few useful patterns.

## Option 1: Distributing data with `nbgitpuller`

For small datasets, the simplest way to share data with your users is via
`nbgitpuller` links. In this case, users click on your link and the dataset
contained in the link's target repository is downloaded to the user's home
directory. Note that a copy of the dataset will be made for each user.

For information on creating and sharing `nbgitpuller` links, see
{ref}`howto/content/nbgitpuller`.

## Option 2: Create a read-only shared folder for data

If your data is large or you don't want copies of it to exist, you can create
a read-only shared folder that users have access to. To do this, follow these
steps:

1. **Log** in to your JupyterHub as an **administrator user**.

2. **Create a terminal session** with your JupyterHub interface.

   ```{image} ../../images/notebook/new-terminal-button.png
   :alt: New terminal button.
   ```

3. **Create a folder** where your data will live. We recommend placing shared
   data in `/srv`. The following command creates two folders (`/srv/data` and
   `/srv/data/my_shared_data_folder`).

   ```bash
   sudo mkdir -p /srv/data/my_shared_data_folder
   ```

4. **Download the data** into this folder. See {ref}`howto/content/add-data` for
   details on how to do this.

5. All users now have read access to the data in this folder.

### Add a link to the shared folder in the user home directory

Optionally, you may also **create a symbolic link to the shared data folder**
that you created above in each **new user's** home directory.

To do this, you can use the server's **user skeleton directory** (`/etc/skel`).
Anything that is placed in this directory will also
show up in a new user's home directory.

To create a link to the shared folder in the user skeleton directory,
follow these steps:

1. `cd` into the skeleton directory:

   ```bash
   cd /etc/skel
   ```

2. **Create a symbolic link** to the data folder

   ```bash
   sudo ln -s /srv/data/my_shared_data_folder my_shared_data_folder
   ```

3. **Confirm that this worked** by logging in as a new user. You can do this
   by opening a new "incognito" browser window and accessing your JupyterHub.
   After you log in as a **new user**, the folder should appear in your new
   user home directory.

From now on, when a new user account is created, their home directory will
have this symbolic link (and any other files in `/etc/skel`) in their home
directory. This will have **no effect on the directories of existing
users**.

## Option 3: Create a directory for users to share Notebooks and other files

You may want a place for users to share files with each other rather than
only having administrators share files with users (Option 2). In this
configuration, any user can put files into `/srv/scratch` that other users
can read. However, only the user that created the file can edit the file.

One way for users to share or "publish" Notebooks in a JupyterHub environment
is to create a shared directory. Any user can create files in the directory,
but only the creator may edit that file afterwards.

For instance, in a Hub with three users, User A develops a Notebook in their
`/home` directory. When it is ready to share, User A copies it to the
`shared` directory. At that time, User B and User C can see User A's
Notebook and run it themselves (or view it in a Dashboard layout
such as `voila` or `panel` if that is running in the Hub), but User B
and User C cannot edit the Notebook. Only User A can make changes.

1. **Log** in to your JupyterHub as an **administrator user**.

2. **Create a terminal session** with your JupyterHub interface.

   ```{image} ../../images/notebook/new-terminal-button.png
   :alt: New terminal button.
   ```

3. **Create a folder** where your data will live. We recommend placing shared
   data in `/srv`. The following command creates a directory `/srv/scratch`

   ```bash
   sudo mkdir -p /srv/scratch
   ```

4. **Change group ownership** of the new folder

   ```bash
   sudo chown  root:jupyterhub-users /srv/scratch
   ```

5. **Change default permissions to use group**. The default permissions for new
   sub-directories uses the global umask (`drwxr-sr-x`), the `chmod g+s` tells
   new files to use the default permissions for the group `jupyterhub-users`
   (`rw-r--r--`)

   ```bash
   sudo chmod 777 /srv/scratch
   sudo chmod g+s /srv/scratch
   ```

6. **Create a symbolic link** to the scratch folder in users home directories

   ```bash
   sudo ln -s /srv/scratch /etc/skel/scratch
   ```

:::{note}
The TLJH Plugin at <https://github.com/kafonek/tljh-shared-directory> installs `voila` and sets up the directories as specified above.
Include `--plugin git+https://github.com/kafonek/tljh-shared-directory` in your deployment startup script to install it.
:::