So I figured I'd do a real quick write up on using PBS + TrueNAS S3. It took me a bit, but honestly pretty quick, easy and painless. The hardest part overall was getting PBS to see the TrueNAS S3 buckets; due to the fact that PBS requires the usage of TLS certificates for S3 endpoints. Since I am using TrueNAS's self signed certificate, all I did was go into the web browser, viewed the UI's certificate in Firefox & copied the SHA256 value and put it in the S3 endpoints fingerprint location. I also used their official S3 guide to get myself set up on the TrueNAS side. (Just make sure TLS is enabled on the TrueNAS side too.
https://cdn.truenas.com/docs/scale/shares/s3/configurings3/
Otherwise everything was painless. With the S3 rollout on TrueNAS 27; backup solutions can be so much easier.
EDIT: Also in Proxmox Backup Server you must enable path style in the s3 endpoint. Was getting 405 errors without it checking that box.
EDIT: I am in the works of rebuilding my homelab, adding ACME DNS-01 for all of my certs across the board here soon. It will likely fair better without the fingerprint requirement and no other configuration will be needed,
Source: r/truenas · by /u/ChubbyWabbit