Hi @bkhwang,
are you speaking of Splunk Enterprise (on premise) or Splunk Cloud?
In Splunk Cloud, you can upload an app from Splunkbase using [Apps -- Find more apps] and there isn't any additional check because the apps are already tested.
If you want to update a custom App, you have two ways: creating directly in Splunk Cloud in [Apps -- Manage apps - Create app] or upload you own [Apps -- Manage apps - Install app from file].
To upload your own app, you have to create it following some criteria, e.g. not using scripts, put all configurations in default and not in local, etc...
You have to create and package your app following the instructions at https://dev.splunk.com/enterprise/docs/releaseapps/packageapps/
After upload, Splunk Cloud makes a check and sometimes (iId say usually!) rejects the app listing and describing the found errors, so you can correct the errors and retry.
If instead you're speaking of Splunk Enterprise there isn't any limitatin to your app, only that it must follow the app structure (folders and files).
Ciao.
Giuseppe
