This post reminded me of a very old article from Yahoo/Tumblr explaining how they were (ab)using Ceph to generate thumbnails on the fly as pictures were uploaded using the Ceph OSD plugin interface.
Unfortunately the post seems to have disappeared from the internet (it was probably around 6 years ago), so here are some other teasers:
Talk is from Lua workshop 2017. Relevant content begins at 15m40s.
https://youtu.be/bGQc-PpJAyk?t=15m40s