Kamal Proxy is a small HTTP proxy designed for seamless zero-downtime deployments of web applications. By running your apps behind Kamal Proxy, changes can be deployed without disrupting ongoing traffic, and no cooperation from the application itself is needed. Kamal Proxy is part of Kamal, offering a complete deployment solution including container packaging. It can be used standalone or with other deployment tools. Host-based routing allows multiple apps on one server, each with its own host. Kamal Proxy also offers automatic TLS certificate management. Environment variables can be used for configuration. Deployments take place with zero downtime, ensuring smooth transitions.
https://github.com/basecamp/kamal-proxy