Add NOVA_SHUTDOWN_TIMEOUT variable

This adds a variable to control the [DEFAULT]/shutdown_timeout
config in nova to control whether or not a guest should have
a graceful shutdown of the OS or if it should just stop
immediately (no timeout). Since devstack uses CirrOS images
by default, the default value for the NOVA_SHUTDOWN_TIMEOUT
variable is 0 which should speed up tempest runs. The default
in nova.conf [1] is 60 seconds.

[1] https://docs.openstack.org/nova/latest/configuration/config.html#DEFAULT.shutdown_timeout

Change-Id: Ida83f70a1c4e61e5248f2bd42b4c24f7ac6d2310
Related-Bug: #1829896

Author: mriedem

lib/nova

@@ -153,6 +153,11 @@ ISCSID_DEBUG_LEVEL=${ISCSID_DEBUG_LEVEL:-4}
 # Other options include "versioned" and "both".
 NOVA_NOTIFICATION_FORMAT=${NOVA_NOTIFICATION_FORMAT:-unversioned}
 
+# Timeout for servers to gracefully shutdown the OS during operations
+# like shelve, rescue, stop, rebuild. Defaults to 0 since the default
+# image in devstack is CirrOS.
+NOVA_SHUTDOWN_TIMEOUT=${NOVA_SHUTDOWN_TIMEOUT:-0}
+
 # Functions
 # ---------
 
@@ -401,6 +406,7 @@ function create_nova_conf {
     iniset $NOVA_CONF DEFAULT instance_name_template "${INSTANCE_NAME_PREFIX}%08x"
     iniset $NOVA_CONF DEFAULT osapi_compute_listen "$NOVA_SERVICE_LISTEN_ADDRESS"
     iniset $NOVA_CONF DEFAULT metadata_listen "$NOVA_SERVICE_LISTEN_ADDRESS"
+    iniset $NOVA_CONF DEFAULT shutdown_timeout $NOVA_SHUTDOWN_TIMEOUT
 
     iniset $NOVA_CONF key_manager backend nova.keymgr.conf_key_mgr.ConfKeyManager