Switch to JupyterHub service

[trungleduc]

Changes

This PR converts extra hub handlers into a hub-managed service. This service can be started by this command:

python -m tljh_repo2docker

The available settings for this service are:

• port: Port of the service; defaults to 6789
• ip: Internal IP of the service; defaults to 127.0.0.1
• default_memory_limit: Default memory limit of a user server; defaults to None
• default_cpu_limit: Default CPU limit of a user server; defaults to None
• machine_profiles: Instead of entering directly the CPU and Memory value, tljh-repo2docker can be configured with pre-defined machine profiles and users can only choose from the available option; defaults to []

Here is an example of registering tljh_repo2docker's service with JupyterHub

# jupyterhub_config.py

from tljh_repo2docker import TLJH_R2D_ADMIN_SCOPE

c.JupyterHub.services.extend(
    [
        {
            "name": "tljh_repo2docker",
            "url": "http://127.0.0.1:6789", # URL must match the `ip` and `port` config
            "command": [
                sys.executable,
                "-m",
                "tljh_repo2docker",
                "--ip",
                "127.0.0.1",
                "--port",
                "6789"
            ],
            "oauth_no_confirm": True,
        }
    ]
)
# Set required scopes for the service and users
c.JupyterHub.load_roles = [
    {
        "description": "Role for tljh_repo2docker service",
        "name": "tljh-repo2docker-service",
        "scopes": ["read:users", "read:servers", "read:roles:users"],
        "services": ["tljh_repo2docker"],
    },
    {
        "name": "user",
        "scopes": [
            "self",
            # access to the serve page
            "access:services!service=tljh_repo2docker",
        ],
    },
]

[jtpio]

Thanks @trungleduc for looking into this!

[jtpio]

Wondering if this snapshot update is intended? It looks like the refresh icon appears instead of "Open Server"

[jtpio]

The navbar changes look relevant due to the switch to the service. So it's likely only the refresh icon.

[trungleduc]

The updated snapshot is for the nav bar, the refresh icon, or the "Open Server" button depending on the runner's processing speed; sometimes it fires the server quickly enough to show the open server button.
We have a maxDiffPixelRatio: 0.001 config to catch this inconsistency

[jtpio]

cc @yuvipanda this is one step towards #72 (in case you are interested in following progress on that)

[yuvipanda]

oooooh will look!

[jtpio]

Thanks!