Add graceful exit.
A SIGUSR1 will cause zuul to queue new events, wait for existing
jobs to finish, then save the queue and exit.
It will likely take quite a while to complete (perhaps an hour),
so it's not implemented as a SIGTERM handler.
Can be used in an init script to implement a graceful restart.
Change-Id: I09fce571e971f16b5d20c5d69d595a05c7f6a4ba
diff --git a/etc/zuul.conf-sample b/etc/zuul.conf-sample
index c1b2a19..41f2386 100644
--- a/etc/zuul.conf-sample
+++ b/etc/zuul.conf-sample
@@ -12,3 +12,4 @@
layout_config=/etc/zuul/layout.yaml
log_config=/etc/zuul/logging.yaml
pidfile=/var/run/zuul/zuul.pid
+state_dir=/var/lib/zuul