openstack/glance
Code Issues Proposed changes

Zero downtime config reload (glance-control)

Browse Source 
Update glance-control to send a SIGHUP rather than
perform a start/stop for the 'reload' operation.

This allows picking up new configuration values without
interrupting the service.

Closes-bug: 1436275
Change-Id: I5a653daa3e582b665c0a2c402cf2d7c9e47e1c38
This commit is contained in:
Stuart McLaren 2014-10-21 16:59:43 +00:00 committed by Louis Taylor
parent 6dc5477a12
commit 0c7f172117
2 changed files with 37 additions and 2 deletions
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13
doc/source/controllingservers.rst
View File

@ -222,3 +222,16 @@ here::
$> sudo glance-control registry restart etc/glance-registry.conf
Stopping glance-registry pid: 17611 signal: 15
Starting glance-registry with /home/jpipes/repos/glance/trunk/etc/glance-registry.conf
Reloading a server
-------------------
You can reload a server with the ``glance-control`` program, as demonstrated
here::
$> sudo glance-control api reload
Reloading glance-api (pid 18506) with signal(1)
A reload sends a SIGHUP signal to the master process and causes new configuration
settings to be picked up without any interruption to the running service (provided
neither bind_host or bind_port has changed).

26
glance/cmd/control.py
View File

@ -54,6 +54,7 @@ CONF = cfg.CONF
ALL_COMMANDS = ['start', 'status', 'stop', 'shutdown', 'restart',
'reload', 'force-reload']
ALL_SERVERS = ['api', 'registry', 'scrubber']
RELOAD_SERVERS = ['glance-api', 'glance-registry']
GRACEFUL_SHUTDOWN_SERVERS = ['glance-api', 'glance-registry',
'glance-scrubber']
MAX_DESCRIPTORS = 32768
@ -242,6 +243,28 @@ def get_pid_file(server, pid_file):
return pid_file
def do_reload(pid_file, server):
if server not in RELOAD_SERVERS:
msg = (_('Reload of %(serv)s not supported') % {'serv': server})
sys.exit(msg)
pid = None
if os.path.exists(pid_file):
with open(pid_file, 'r') as pidfile:
pid = int(pidfile.read().strip())
else:
msg = (_('Server %(serv)s is stopped') % {'serv': server})
sys.exit(msg)
sig = signal.SIGHUP
try:
print(_('Reloading %(serv)s (pid %(pid)s) with signal(%(sig)s)')
% {'serv': server, 'pid': pid, 'sig': sig})
os.kill(pid, sig)
except OSError:
print(_("Process %d not running") % pid)
def do_stop(server, args, graceful=False):
if graceful and server in GRACEFUL_SHUTDOWN_SERVERS:
sig = signal.SIGHUP
@ -383,8 +406,7 @@ def main():
if CONF.server.command in ('reload', 'force-reload'):
for server in CONF.server.servers:
do_stop(server, CONF.server.args, graceful=True)
pid_file = get_pid_file(server, CONF.pid_file)
do_start('Restart', pid_file, server, CONF.server.args)
do_reload(pid_file, server)
sys.exit(exitcode)