I configured Free Radical to use S3 to serve media assets, like images and videos, almost immediately after launching it. There are compelling reasons to use something like S3 instead of serving those files directly from the Mastodon server, such as freeing that server from getting clogged with a zillion media requests. In theory, it should be cheaper, too.

Well.

In October 2022, our AWS S3 storage bill was $12.54 for storing about 330GB of media files and serving about 113GB of files to users.

I woke up to the terrible news that our good friends on another instance had lost their database during a software upgrade. Godspeed and good luck in bringing it back online. We’re pulling for you!

The Free Radical site backs itself up hourly to a private S3 bucket, and keeps a month’s worth of these snapshots. It’s configured to upload all media files to S3 and serve them from there. In the event of a complete server failure, I could – assuming all goes well – re-deploy the software on a new server and restore from backup without losing more than just users and posts created since the last hour’s backup.

I’m serving Free Radical’s images etc. from S3. When I updated to Mastodon v2.1.0, I noticed that all the page’s images were missing. Safari’s Show JavaScript Console menu revealed a lot of errors like:

[Error] Refused to load https://s3-us-west-2.amazonaws.com/freeradical-system/accounts/avatars/000/014/309/static/91f9782fad3f6284.png because it does not appear in the img-src directive of the Content Security Policy.

Turns out that some time between the releases of v2.0.0 and v2.1.0, the Mastodon switched from generating S3 URLs like:

A couple of weeks ago, I described a month’s worth of experience with hosting Free Radical’s media on S3. This update responds to some predictions now that I have an entire calendar month under my belt.

When I was estimating Free Radical’s operating costs, I predicted that S3 storage growth would be linear. That turned out to be very much the case.

I had no idea how much it would cost to host a Mastodon instance. This is for everyone like I was who’s thinking about running their own server but wants to know what to expect.

Free Radical currently has 62 users. The numbers here are what I pay our small little instance and would certainly jump up if we grew by a factor of 100x.

This morning, I moved all of the user-generated content on Free Radical from local storage to S3. It was completely painless and Just Worked – yay! There are a few reasons why this can be a great idea: