Decidim on Docker
There is an image available for a default Decidim app, with core modules. It gets updated with each new version release.
Note that the usual requirements for Docker and Rails deployments apply here:
A persistent volume is required for file uploads, logs and any changing, persisted data. Docker images are stateless by design, so they can be easily updated, restarted and replicated.
Rails file uploads are handled by Rails' Active Storage. Their guide will have the ins and outs of configuring file storage on Rails, including delegating it to file storage in the cloud, for example.
For a more elaborate example of docker compose usage, including setting volumes and SSL, among other things, please see the docker-compose.yml for the Decidim instance deployed for the city of Sabadell, in Catalunya.