jupyterhub/docs/source/reference/rest.md

# Using JupyterHub's REST API

This section will give you information on:

- what you can do with the API
- create an API token
- add API tokens to the config files
- make an API request programmatically using the requests library
- learn more about JupyterHub's API

## What you can do with the API

Using the [JupyterHub REST API][], you can perform actions on the Hub,
such as:

- checking which users are active
- adding or removing users
- stopping or starting single user notebook servers
- authenticating services

A [REST](https://en.wikipedia.org/wiki/Representational_state_transfer)
API provides a standard way for users to get and send information to the
Hub.

## Create an API token

To send requests using JupyterHub API, you must pass an API token with
the request.

As of [version 0.6.0](../changelog.html), the preferred way of
generating an API token is:

```bash
openssl rand -hex 32
```

This `openssl` command generates a potential token that can then be
added to JupyterHub using `.api_tokens` configuration setting in
`jupyterhub_config.py`.

Alternatively, use the `jupyterhub token` command to generate a token
for a specific hub user by passing the 'username':

```bash
jupyterhub token <username>
```

This command generates a random string to use as a token and registers
it for the given user with the Hub's database.

In [version 0.8.0](../changelog.html), a TOKEN request page for
generating an API token is available from the JupyterHub user interface:

![Request API TOKEN page](../images/token-request.png)

![API TOKEN success page](../images/token-request-success.png)

## Add API tokens to the config file

You may also add a dictionary of API tokens and usernames to the hub's
configuration file, `jupyterhub_config.py` (note that
the **key** is the 'secret-token' while the **value** is the 'username'):

```python
c.JupyterHub.api_tokens = {
    'secret-token': 'username',
}
```

## Make an API request

To authenticate your requests, pass the API token in the request's
Authorization header.

### Use requests

Using the popular Python [requests](http://docs.python-requests.org/en/master/)
library, here's example code to make an API request for the users of a JupyterHub
deployment. An API GET request is made, and the request sends an API token for
authorization. The response contains information about the users:

```python
import requests

api_url = 'http://127.0.0.1:8081/hub/api'

r = requests.get(api_url + '/users',
    headers={
             'Authorization': 'token %s' % token,
            }
    )

r.raise_for_status()
users = r.json()
```

This example provides a slightly more complicated request, yet the
process is very similar:

```python
import requests

api_url = 'http://127.0.0.1:8081/hub/api'

data = {'name': 'mygroup', 'users': ['user1', 'user2']}

r = requests.post(api_url + '/groups/formgrade-data301/users',
    headers={
             'Authorization': 'token %s' % token,
            },
    json=data
)
r.raise_for_status()
r.json()
```

The same API token can also authorize access to the [Jupyter Notebook REST API][]
provided by notebook servers managed by JupyterHub.
To do so, the following must be true:

1. The token used is tied to an admin user or service
2. `c.JupyterHub.admin_access` must be set to `True`

## Enabling users to spawn multiple named-servers via the API

With JupyterHub version 0.8, support for multiple servers per user has landed.
Prior to that, each user could only launch a single default server via the API
like this:

```bash
curl -X POST -H "Authorization: token <token>" "http://127.0.0.1:8081/hub/api/users/<user>/server"
```

With the named-server functionality, it's now possible to launch more than one
specifically named servers against a given user.  This could be used, for instance,
to launch each server based on a different image.

First you must enable named-servers by including the following setting in the `jupyterhub_config.py` file.

`c.JupyterHub.allow_named_servers = True`

If using the [zero-to-jupyterhub-k8s](https://github.com/jupyterhub/zero-to-jupyterhub-k8s) set-up to run JupyterHub, 
then instead of editing the `jupyterhub_config.py` file directly, you could pass 
the following as part of the `config.yaml` file, as per the [tutorial](https://zero-to-jupyterhub.readthedocs.io/en/latest/):

```bash
hub:
  extraConfig: |
    c.JupyterHub.allow_named_servers = True
```

With that setting in place, a new named-server is activated like this:
```bash
curl -X POST -H "Authorization: token <token>" "http://127.0.0.1:8081/hub/api/users/<user>/servers/<serverA>"
curl -X POST -H "Authorization: token <token>" "http://127.0.0.1:8081/hub/api/users/<user>/servers/<serverB>"
```

The same servers can be stopped by substituting `DELETE` for `POST` above.

### Some caveats for using named-servers

The named-server capabilities are not fully implemented for JupyterHub as yet.
While it's possible to start/stop a server via the API, the UI on the 
JupyterHub control-panel has not been implemented, and so it may not be obvious
to those viewing the panel that a named-server may be running for a given user.

For named-servers via the API to work, the spawner used to spawn these servers
will need to be able to handle the case of multiple servers per user and ensure
uniqueness of names, particularly if servers are spawned via docker containers
or kubernetes pods.


## Learn more about the API

You can see the full [JupyterHub REST API][] for details. This REST API Spec can
be viewed in a more [interactive style on swagger's petstore][].
Both resources contain the same information and differ only in its display.
Note: The Swagger specification is being renamed the [OpenAPI Initiative][].

[interactive style on swagger's petstore]: http://petstore.swagger.io/?url=https://raw.githubusercontent.com/jupyterhub/jupyterhub/master/docs/rest-api.yml#!/default
[OpenAPI Initiative]: https://www.openapis.org/
[JupyterHub REST API]: ../_static/rest-api/index.html
[Jupyter Notebook REST API]: http://petstore.swagger.io/?url=https://raw.githubusercontent.com/jupyter/notebook/master/notebook/services/api/api.yaml