Shedding old code with ecdysis: graceful restarts for Rust services at Cloudflare

Cloudflare open-sourced ecdysis, a Rust library enabling zero-downtime graceful process restarts for high-traffic network services.

• •The naive restart approach creates connection gaps and drops live connections; SO_REUSEPORT introduces orphaned connections during process transitions
• •ecdysis follows NGINX's fork-exec model: parent forks a child, child inherits listening sockets via named pipe, and parent drains existing connections before shutting down
• •The child gets a safe initialization window; if it crashes, the parent continues serving with no dropped connections
• •Provides first-class Tokio async integration, systemd-notify support, and systemd socket activation out of the box
• •Security is maintained via fork-then-exec (clean address space), explicit fd inheritance with CLOEXEC, though seccomp filters must allow fork/execve