Docker containers encapsulate everything you need to describe and run a process, but the lifecycle of a process remains the same: it starts, it runs for a while, and then it ends. This talk will demonstrate how to combine Docker with a tool called CRIU to “roll-back” running processes to an earlier state. CRIU, which stands for Checkpoint & Restore in User Space, creates a complete snapshot of the state of a process, including things like memory contents, file descriptors, and even open tcp connections. It can be used for suspending and resuming processes, or live migrating them from one machine to another. Our developer tool, Tonic, uses it to allow developers to change their code in the middle of a program without restarting from the beginning. We’ll show how we use the Docker Remote API to do this in production thousands of times a day.
