Cache plugin manifests to improve meeting creation speed

[gustavotrott]

This is actually a BBB Core issue, but I’m opening it here to keep all plugin-related issues in one place.

Currently, all plugin manifests are downloaded during the /create request. When a plugin is hosted on an external server, this can add several seconds to the Create request’s response time because the manifests need to be fetched.

I suggest adding a mechanism to cache manifest files on the BBB server using a hash based on the manifest URL. Before downloading from the external URL, BBB would check if the file is already cached and reuse it if available. This would significantly reduce meeting creation time.

The feature could be controlled with a config flag:
pluginManifestCacheEnabled=true

For cache invalidation, the hash could be generated using ManifestURL + currentDate(Y-m-d), ensuring that BBB retrieves a fresh manifest once per day.

To prevent stale files from accumulating, cache files could be stored under /var/bigbluebutton/plugin-manifests-cache/, which would be included in BBB’s routine cleanup process.