Even though the application has been renamed from Piwik to Matomo, the most of the composer packages are still namespaced using piwik. This is being updated for Matomo 4 (matomo-org/matomo#12519).

1. Create a new app.
2. Connect a mysql database to the app.
3. Update config for database connection in config.ini.php as needed
4. Add config settings for SALT and TRUSTED_HOST (the domain name you access the Matomo app from)
5. Deploy app

The filesystem is ephemeral and will be wiped out on each deploy. Any settings that Matomo automatically updates in vendor/piwik/piwik/config/config.ini.php need to be manually duplicated in the config.ini.php in the repo, or they will be wiped out the next time the app is rebuilt.

Plugins are managed by composer. Plugins installed through Matomo's web interface will get erased when the app is rebuilt.

Most Matomo plugins do not include a composer.json file so you'll need to use the package option and define the settings for each plugin manually. See the configuration for the SecurityInfo plugin in composer.json for an example. By sure that "type": "piwik-plugin" is defined in the plugins package.json file.

1. composer require [plugin] to install the plugin
2. Add plugin to Plugins[] and PluginsInstalled[] lists in config.ini.php so that the plugin is activated when the app is re-deployed.

This setup is configured to use the GeoIp2 plugin included in the core Matomo package. The GeoLite databases are downloaded using a custom buildpack https://github.com/danstiner/heroku-buildpack-geoip-geolite2 defined in .buildpacks.

You can turn on this geolocation method on in Settings > System > Geolocation. Rebuilding the app will get a fresh copy of the GeoLite databases. You can also configure the plugin to download an updated database periodically.

Heroku no longer uses the .buildpacks file, so you will need to specify buildpacks using the heroku cli.

Install the cli if needed, then run the following to specify the buildpacks for your app:

heroku buildpacks:add --index 1 https://github.com/danstiner/heroku-buildpack-geoip-geolite2
heroku buildpacks:add --index 2 heroku/php