# Upgrading

## Backup

Before performing an upgrade, you might want to back up some components of the stack.

### Database

JupyterHub keeps the state in a sqlite database, with information such as the last login and whether a user is an admin or not.

TLJH keeps the database in the `/opt/tljh/state` directory on the server. The full path to the database is `/opt/tljh/state/jupyterhub.sqlite`.

To know more about backing up the database please refer to:

- [The JupyterHub documentation](https://jupyterhub.readthedocs.io/en/stable/admin/upgrading.html#backup-database-config)
- [The TLJH documentation on the state files](http://tljh.jupyter.org/en/latest/topic/installer-actions.html#state-files)

For more info on where TLJH is installed: [What does the installer do?](http://tljh.jupyter.org/en/latest/topic/installer-actions.html)

### Plasma TLJH Plugin

This TLJH plugin is a regular Python package.

It is installed in `/opt/tljh/hub/lib/python3.6/site-packages/tljh_plasma`, and doesn't need to be backed up
as it doesn't hold any state.

### User Environments

The user environments correspond to Docker images on the host. There is no need to back them up as they
will stay untouched if not removed manually.

### User Data

It is generally recommended to have a backup strategy for important data such as user data.

This can be achieved by setting up tools that for example sync the user home directories to another machine on a regular basis.

Check out the {ref}`persistence-user-data` section to know more about user data.

## Running the playbook

To perform an upgrade of the setup, you can re-run the playbooks as explained in {ref}`install-ansible`.

Re-running the playbooks will:

- Update the TLJH Plasma plugin
- Update TLJH
- Restart JupyterHub and the Proxy to take new changes into account

However, performing an upgrade does not:

- Stop user servers
- Remove user environments (Docker images)
- Delete user data

In most cases, it is enough to only run the `tljh.yml` playbook to perform the upgrade.

Refer to {ref}`install-individual-playbook` for more info.