This is only needed once

Before you can start using this service, you need to enable the access from JupyterHub into your account on the target platform.

A unique SSH key pair is created for this purpose, and you will need to append the generated public SSH key into your ~/.ssh/authorized_keys in your ECMWF HOME space.

You will need to access  Atos HPCF,  ECS or VDI services via other means. From a terminal in one of those systems, you can then:

$ grep -q $USER@jupyter ~/.ssh/authorized_keys || echo "ssh-ed25519 AAAA...." >> ~/.ssh/authorized_keys

Note you should replace "ssh-ed25519 AAAA...." by the actual value of your SSH key that appears in the JupyterHub portal.