Hide the launch button when all backends are disabled

[MountComb]

Describe the bug

context When I disable the default binder link in _config.yml:

launch_buttons:
  binderhub_url: ""

expectation I expected the launch button to disappear.

bug But instead the launch button still showed up on the top, with an empty dropdown list:

Also, if I set repository url to empty, an error occors:

ValueError: You must provide the key: `repository_url` to use launch buttons.

problem This is a problem for people trying to fully disable the launch button.

workaround Currently the launch button can be disabled directly via the sphinx config:

sphinx:
  config:
    html_theme_options:
      launch_buttons: {}

Reproduce the bug

jupyter-book create test
cat >> _config.yml <<EOF
launch_buttons:
  binderhub_url: ""
EOF
jupyter-book build test

see _build/html/notebooks.html and _build/html/markdown-notebooks.html

List your environment

$ jupyter-book --version
Jupyter Book      : 0.13.0
External ToC      : 0.2.4
MyST-Parser       : 0.15.2
MyST-NB           : 0.13.2
Sphinx Book Theme : 0.3.2
Jupyter-Cache     : 0.4.3
NbClient          : 0.5.13

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[vfscalfani]

I had the same issue, thanks so much for sharing this workaround. One minor limitation with the workaround is that it also disables the GitHub Repository and Issues links. I could not not find a workaround for that yet; that is disable/ hide the launch button, but keep the GitHub button.

[vvssttkk]

the same problem too

[jeromedockes]

another workaround could be to hide the button, adding a rule like

.menu-dropdown-launch-buttons {
    display: none !important;
}

to a .css file in the _static folder

of course this isn't very robust and would need to be updated whenever a new jupyter book version changes the class name of the launch button