Kamal is an open-source command-line tool for deploying containerised web applications to servers the user controls, from bare metal to cloud virtual machines. 37signals built it for the Rails framework, but it works with any containerisable web app. It provides zero-downtime deploys, rolling restarts, remote builds and management of accessory services such as databases, configured through a single config file and SSH.
37signals LLC, the company behind Basecamp and HEY, publishes Kamal under the MIT licence and states that its own applications were moved from cloud hosting to its own hardware with this toolkit. The company's terms describe infrastructure located in the United States, so the vendor is a US company. Because Kamal runs on infrastructure the organisation controls and has no vendor cloud component, European organisations can deploy it on servers in the EU and keep application data within their own environment.