# Confused by binderhub/launcher extra\_args

**URL:** <https://discourse.jupyter.org/t/confused-by-binderhub-launcher-extra-args/15716>\
**Category:** BinderHub\
**Tags:** help-wanted\
**Created:** [September 9, 2022, 6:56pm UTC](https://discourse.jupyter.org/t/confused-by-binderhub-launcher-extra-args/15716 "2022-09-09T18:56:52Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![afterthought](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.jupyter.org/afterthought/32/7911_2.png) [@afterthought](https://discourse.jupyter.org/u/afterthought)\
**Post date:** [September 9, 2022, 6:56pm UTC](https://discourse.jupyter.org/t/confused-by-binderhub-launcher-extra-args/15716/1 "2022-09-09T18:56:52Z")

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[https://binderhub.readthedocs.io/en/latest/reference/launcher.html#binderhub.launcher.Launcher.launch](https://binderhub.readthedocs.io/en/latest/reference/launcher.html#binderhub.launcher.Launcher.launch)

The launch function takes an extra\_args param that will be posted to the jupyterhub api. I am struggling to figure out how to set these. I assumed maybe adding ?myparam=foobar to the url might work. However, i do not see this documented anywhere and it doesn’t seem to work for me.

I am using:

[0.2.0-0.dev.git.2752.h3450e52]  
[1.1.3-n721.h0acbcf43]

My goal is to pass the profile slug to jupyterhub to avoid conflicts with other profiles not meant for binders.

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**Author:** ![manics](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.jupyter.org/manics/32/85_2.png) [@manics](https://discourse.jupyter.org/u/manics)\
**Post date:** [September 10, 2022, 9:19pm UTC](https://discourse.jupyter.org/t/confused-by-binderhub-launcher-extra-args/15716/2 "2022-09-10T21:19:04Z")

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The document you’ve linked to describes an internal BinderHub Python function. It’s not exposed via any public URL parameters.

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<div class="post-metadata">

**Author:** ![afterthought](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.jupyter.org/afterthought/32/7911_2.png) [@afterthought](https://discourse.jupyter.org/u/afterthought)\
**Post date:** [September 12, 2022, 8:02pm UTC](https://discourse.jupyter.org/t/confused-by-binderhub-launcher-extra-args/15716/3 "2022-09-12T20:02:36Z")

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Fair enough. It would however be quite nice if we could have Binderhub specify a profile in Jupyterhub.

p.s. It doesn’t really seem internal if it’s documented on the Launcher spec?

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<div class="post-metadata">

**Author:** ![afterthought](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.jupyter.org/afterthought/32/7911_2.png) [@afterthought](https://discourse.jupyter.org/u/afterthought)\
**Post date:** [September 14, 2022, 3:38am UTC](https://discourse.jupyter.org/t/confused-by-binderhub-launcher-extra-args/15716/4 "2022-09-14T03:38:09Z")

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Also, this: [Query parameter naming scheme? · Issue #712 · jupyterhub/binderhub · GitHub](https://github.com/jupyterhub/binderhub/issues/712)