cloudflare / shellflip

Graceful process restarts in Rust

shellflip

Graceful process restarts in Rust.

This crate facilitates upgrading or reconfiguring a service without disrupting existing connections. This is achieved by forking the process and communicating a small amount of state between the old and new processes; once the new process has started successfully the old process may terminate.

This crate has the following goals:

• No old code keeps running after a successful upgrade (and inevitable shutdown of the old process)
• The new process has a grace period for performing initialisation
• Crashing during initialisation is OK
• Only a single upgrade is ever run in parallel
• It is possible for the user/process initiating the upgrade to know if the upgrade succeeded

Inspired by the tableflip go package but not a direct replacement.

Using the library

A full example is given in the restarter example service.

The main struct of interest is RestartConfig which has methods for detecting or initiating restart. For shutting down a restarted process, the ShutdownCoordinator provides the means for both signalling a shutdown event to spawned tasks, and awaiting their completion.

License

BSD licensed. See the LICENSE file for details.

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