Create ability to refresh user thumbnails after deleting media_store cache on homeserver

[gbolcer]

Discussed in https://github.com/matrix-org/synapse/discussions/10850

^{Originally posted by gbolcer September 19, 2021}
I ran out of disk space on my homeserver and there was some unwanted user avatars from blocked users. To do this, I deleted the content in the media_store incorrectly--on the file system versus through the API. I mistakenly thought it would just re-populate the cache.

Right now I can get the homeserver.com/_matrix/media/r0/download/matrix.org/nXyZyXXXXX URL for the avatar which is broken. If I swap out homeserver.com for matrix.org I get the correct avatar (at least for the ones registered at matrix.org).

Is there an easy way to repopulate the local media_store cache on the homeserver? Force it to reload the images from the original user account/cache?

[erikjohnston]

FTR it looks like you can manually call the purge remote media admin API on the files you deleted (as it ignores missing files), which should cause Synapse to refetch the remote media again next time it is requested.

[gbolcer]

Thank you, I did end up calling the purge API, but it didn't seem to fix it. Do I need to call purge with each individual URL? Let me test with one and see what happens.

Just for the record, I am running Synapse 1.37.1 as the upgrade to 1.42/1.43rc caused my Java SDK to break for my bot.

[dklimpel]

Related or duplicate to #1555 ?

[richvdh]

looks like it.