# Scivision - Hub23 chat 25/05/22

Use case:
- each of the three post-docs hve sample notebooks. These are online in the form of binder links. These take a long time to spin up.

Jupyterhub:
- method to divvy up compute when jupyter is the interface.
- Q. Can you use any interface?
- come via jupyter plugin python packages.
- Two different distributions of jupyterhub - 1) scalable, 2) littlest jupyterhub, single machine.
- Uses:
- active work. researchers.
- features:
- home dir
- persistent
- shared directories
- pre-defined environments. containers. packages installed here aren't necessary kept.

Binderhub:
- jupyterhub + dynamic computational environment.
- repo2docker + proxy serve to redirect user to mybinder/url.
- Uses:
- interactive tutorials
- scientific comms
- reproducible papers
- interactive docs
- docs.
- Features:
- dynamic env generation
- generated URLs for easy sharing
- ephemeral.

The only thing that is useful for researchers from binderhub is the dynamic environment generation.

Future work: bringing `persistent binderhub` which is repo2docker functionality in Jupyterhub.

This will be a feature flag to jupyterhub.

Binder is slow because it is building a docker image. But even just one commit will cause it to build again. `nbgitpuller` is a way round this because you technically. have a separate binder branch that has a separate binder link and use nbgitpuller to pull from master. Binder only builds then when there are new commits into the binder branch.
alejandro - is `.binder` enough to do avoid a reset? No. it will still rebuild if there is a commit on your branch.
there is a `repo2docker` action.

binder is also slow because of the federation redirector:
- checks if novel repo
- if yes, where did I build it lst time, send it there.
- also what is the load of clusters.
- members do not share a container registry.
- you're also limited at the kubernetes level.
- pods need provisions
- if nodes are full time taken to provide new nodes.

- workshops hub23 on jupyerhub.
- repo2docker will work with a hub.
- you can spin up a new hub23.
- **Requirementsx for a new Hub**
- What GPU/CPU is needed?
- What software?
- 2i2c.
- Dask/xarray is not currently available on Hub23. Not part of the roadmap, but could be.