Using the Snapcraft app package Plume which is a publishing/blogging package using ActivityPub.
The only, current problem is when an instance other than the one I've installed attempts to 'like' or 'boost' a post it's unable to retrieve an SSL certificate (Let's Encrypt). Mastodon returns this error:
503 Remove SSL certificate could not be verified
A reverse proxy is used on the Plume server.
The SSL cert is properly configured in the Apache .vhost file and is working when accessing via https.
The Snapcraft SSL directory is empty for this app. Apparently Snapcraft does not permit adding symlink (as su) which I'd thought would be a straightforward way to correct this.
Over all this Plume instance does federate using Activity Hub both in and outbound.
Have tried inquiring at Snapcraft and the Plume developers (it's in alpha) with no success.
Wondering if anyone has come across a similar issue with a Snapcraft install?