Docker container for Alerta based on the offical docker container found here. The only difference between this container and the offical one is that this container includes a plugin for sending alerts via matrix.
You can find the image on Docker Hub here and the source code can be found here with a mirror on GitHub
For setting up Alerta you can follow the instructions for the offical alerta container, as they are the same for this container.
To configure the matrix plugin you can follow the instructions found in the git repo here or in the alerta-contrib git repo here.