Launch links - to help communities craft links launching directly

[consideRatio]

This issue is meant to be an umbrella issue to capture work related to enabling our communities create links where users launch directly with link-defined service choices.

Related work

This is a brain dump of work that I see related to helping our communities make use of "launch links" - links that for a user that is able to login or already logged in then either automatically launches a server takes them to an already started server.

• Add "explanation" docs to jupyterhub/jupyterhub related to Spawner.options_form
  • how spawner's can provide options_form to present a form with "Server options" for users
  • clarifying how the /hub/spawn web request handler can accept both GET and POST requests to launch a server
  • how a GET request with query parameters (besides next=) will trigger a launch
  • options_from_query and options_from_form, and how the former relies on the later by default
• Enable nbgitpuller's link generator to generate launch links bypassing server options
  • In scope for nbgitpuller: document "how to" identify a jupyterhub's launch options that can be passed.
  • Out of scope for nbgitpuller docs: document how these Spawner things work, so nbgitpuller should link to the "explanation" docs added to jupyterhub/jupyterhub for that.
• Add 2i2c docs about launch links
  • Should first clarify how to just start a server (without nbgitpuller involved)
  • Should then also clarify that the nbgitpuller link generator can be used together with this
• Consider if a blog post should be written about this work -> write and publish it

Related

• Related notes in nbgitpuller
  Add a FAQ entry for 'nbgitpuller link selecting profile options' jupyterhub/nbgitpuller#322 (comment)
• Bonus work: add non-reference docs for KubeSpawner's profile_list
  • Add a tutorial "Exposing server options with profile_list" to docs jupyterhub/kubespawner#784
• Request from leap community to craft direct launch links with nbgitpuller functionality: https://2i2c.freshdesk.com/a/tickets/389