Source Code

Our goal is to provide the best possible Mastodon experience for our members. One way to deliver on that is by delivering the most up-to-date Mastodon code. We "run off main", which means using the latest commits to the main branch of the Mastodon codebase found on the project's official GitHub repository.

We take a clean copy of the latest Mastodon code and then apply a limited set of modification with a custom script. We then build the modified code inside a Docker container, publish it to GitHub Container Registry, for consumption by our Kubernetes cluster.

Our server specific customizations include:

  • Customizing the Mastodon logo, if needed, for events like Pride Month (SVG)
  • Raising the post character count limit from 500 to 640
  • Removing the Hiredis driver in favor of the native Redis driver
  • Adding the Elephant and Tangerine themes (vmstan/mastodon #6)

Individual container builds may include additional changes which are being tested on vmst.io, and may be sourced from PR's in the project repository or in other development repos.

Container Availability

Primary Image

Our customized container image is available from both Docker and GitHub container registries. This is suitable for the web/Puma and Sidekiq services.

Streaming Image

Mastodon 4.3-based images and beyond use a seperate container image for the Streaming API.

Redis TLS Changes

DigitalOcean requires encrypted/TLS connections to their managed Redis services, however the Mastodon codebase uses a Redis driver (hiredis) which does not have a native TLS capability. To accommodate this, we have in the past used HAProxy or Stunnel to take the un-encrypted connection requests and encrypt those connections between the Mastodon components and Redis.

We have chosen to remove the hiredis driver from our installation and use redis-rb instead. Using the native redis-rb driver provides support for TLS connections. This is done by patching a stock Mastodon installation with the following commands, downloading updated bundles and node components, and recompiling:

sed -i '/gem '\''hiredis'\'', '\''~> 0.6'\''/d' ./Gemfile
sed -i '/hiredis/d' ./Gemfile.lock
sed -i '/hiredis/d' ./lib/mastodon/redis_config.rb
sed -i '/hiredis/d' ./lib/tasks/mastodon.rake
sed -i 's/, driver: :hiredis//g' ./app/lib/redis_configuration.rb
sed -i 's/, require: \['\''redis'\'', '\''redis\/connection\/hiredis'\''\]//' ./Gemfile

Compared to running with hiredis through HAProxy or Stunnel, we have not seen any negative impact in performance by using redis-rb.

Character Limit Change

Mastodon does not have an individual environment variable that allows this to be easily changed, but as of version 4.3 can be done by changing the hard-coded limit in app/validators/status_length_validator.rb

sed -i '' 's/500/640/g' app/validators/status_length_validator.rb
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