My pluggable workspace definitions are not showing up in my project.

If you create a Compute Environment with pluggable definitions, for example, those documented here...

...but the workspace icons do not show up when you look at the workspaces tab of your project, ask your admin to verify if the following Feature Flag is set to true or false...

ShortLived.PluggableInteractiveSessionSubdomains

If this is set to false then the following must be added to the httpProxy stanza of the pluggable workbook definition,

requireSubdomain: false

For example...

 jupyter:
   title: "Jupyter (Python, R, Julia)"
   iconUrl: "https://raw.github.com/dominodatalab/workspace-configs/develop/workspace-logos/Jupyter.svg?sanitize=true"
   start: [ "/var/opt/workspaces/jupyter/start" ]
   httpProxy:
     requireSubdomain: false
     port: 8888
     rewrite: false
     internalPath: "/{{#if pathToOpen}}tree/{{pathToOpen}}{{/if}}"
   supportedFileExtensions: [ ".ipynb" ]