Package sdnotify implements both sides of the systemd readiness
protocol. Servers can use sdnotify.Ready() to signal that they are
ready to receive traffic, and process managers can use
sdnotify.Exec() to run processes that implement this protocol.
Exec the given command in the background using the systemd
notification protocol. This function returns once the command has
either exited or signaled that it is ready. If the command exits
with a non-zero status before signaling readiness, returns an
exec.ExitError.
Ready sends a readiness signal using the systemd notification
protocol. It should be called (once) by a server after it has
completed its initialization (including but not necessarily limited
to binding ports) and is ready to receive traffic.