[Twisted-Python] twistctl - start/stop/restart revisited
Clark C. Evans
cce at clarkevans.com
Sat Apr 5 16:14:16 MST 2003
Toward the end of the discussion this past morning, we seemed
to have come to the agreement that start/stop/restart behavior
does not belong in twistd. So, I've taken my original submit
and rephrased it as 'twistctl' which is a wrapper on twistd
providing those features.
To get twistctl to work nicely with twistd, a few refactors
in twistd were needed:
1. refactor runApp to factor out the signal code into
'signalApp' so that killApp in twistctl could use it.
In general, runApp is quite huge and could use
a few breakdowns anyway
2. refactor the code to get the passphrase (if the
application is encrypted) and the code which
parses options in run() into a 'parseOptions'
method so that it can be called from twistctl
Neither of these changes affect behavior, they only
expose chunks of reusable code for twistctl
This is a first pass of this, and I'd like to do two
things in the repository: (a) commit the twistd.py.diff
changes, and (b) to put twistctl into the sandbox so
that people can play with it over the next month or
so and after we have a better idea of how it should
behave, we can then add it to the scripts directory.
The twistctl script needs help in many areas:
1. Moshez objected to the killApp implementation,
when I get time I'll look at it. But right now
it works on my platform just wonderfully.
The beauty of open source projects is that people
can hack at it till it works for everyone...
2. The restartApp and startApp behavior are not
exactly clear as to how they should use -shutdown.tap
and a bit more research and experimenting is
needed before this should be formalized. Really,
I'm still too new to taps to grok this fully.
In particular, Moshez said that he thinks this script
should *call* the twistd script via OS methods and
thus the refactor above is not needed. I respectfully
disagree with his assertion. Calling python from python
via python call mechanism is far superior as it allows
for better error handling, is less platform dependent,
and numerous other factors; such as being able to
send a passphrase between the two modules easily.
Anyway, please comment. And Glyph, I'd like permission
to commit the twistd.py.diff as specified below.
Clark
-------------- next part --------------
--- twistd.py.orig Sat Apr 5 17:37:59 2003
+++ twistd.py Sat Apr 5 17:36:14 2003
@@ -1,4 +1,3 @@
-
# Copyright (C) 2001 Matthew W. Lefkowitz
#
# This library is free software; you can redistribute it and/or
@@ -190,11 +189,11 @@
return filename, decode, mode
-def loadApplication(config, passphrase):
+def loadApplication(config):
filename, decode, mode = createApplicationDecoder(config)
if config['encrypted']:
data = open(filename, 'rb').read()
- data = decrypt(passphrase, data)
+ data = decrypt(config['passphrase'], data)
try:
return decode(filename, data)
except:
@@ -211,6 +210,33 @@
import pdb
pdb.set_trace()
+def signalApp(config, signal = 0):
+ if os.path.exists(config['pidfile']):
+ try:
+ pid = int(open(config['pidfile']).read())
+ except ValueError:
+ msg = 'Pidfile %s contains non numeric value'
+ sys.exit(msg % config['pidfile'])
+
+ try:
+ os.kill(pid, signal)
+ except OSError, why:
+ if why[0] == errno.ESRCH:
+ # The pid doesnt exists.
+ if not config['quiet']:
+ print 'Removing stale pidfile %s' % config['pidfile']
+ os.remove(config['pidfile'])
+ else:
+ msg = 'Can\'t check status of PID %s from pidfile %s: %s'
+ sys.exit(msg % (pid, config['pidfile'], why[1]))
+ else:
+ if not(signal):
+ sys.exit("""\
+Another twistd server is running, PID %s\n
+This could either be a previously started instance of your application or a
+different application entirely. To start a new one, either run it in some other
+directory, or use my --pidfile and --logfile parameters to avoid clashes.
+""" % pid)
def runApp(config):
global initRun
@@ -238,39 +264,11 @@
# only posix can fork, and debugging requires nodaemon
config['nodaemon'] = 1
- if config['encrypted']:
- import getpass
- passphrase = getpass.getpass('Passphrase: ')
- else:
- passphrase = None
-
# Load the servers.
# This will fix up accidental function definitions in evaluation spaces
# and the like.
initRun = 0
- if os.path.exists(config['pidfile']):
- try:
- pid = int(open(config['pidfile']).read())
- except ValueError:
- sys.exit('Pidfile %s contains non numeric value' % config['pidfile'])
-
- try:
- os.kill(pid, 0)
- except OSError, why:
- if why[0] == errno.ESRCH:
- # The pid doesnt exists.
- if not config['quiet']:
- print 'Removing stale pidfile %s' % config['pidfile']
- os.remove(config['pidfile'])
- else:
- sys.exit('Can\'t check status of PID %s from pidfile %s: %s' % (pid, config['pidfile'], why[1]))
- else:
- sys.exit("""\
-Another twistd server is running, PID %s\n
-This could either be a previously started instance of your application or a
-different application entirely. To start a new one, either run it in some other
-directory, or use my --pidfile and --logfile parameters to avoid clashes.
-""" % pid)
+ signalApp(config)
if config['logfile'] == '-':
if not config['nodaemon']:
@@ -316,7 +314,7 @@
log.msg('reactor class: %s' % reactor.__class__)
try:
- application = loadApplication(config, passphrase)
+ application = loadApplication(config)
except Exception, e:
s = "Failed to load application: %s" % (e,)
traceback.print_exc(file=log.logfile)
@@ -457,18 +455,22 @@
log.err("--report-profile specified but application has no name (--appname unspecified)")
log.msg("Server Shut Down.")
-
-def run():
+def parseOptions(config):
# make default be "--help"
if len(sys.argv) == 1:
sys.argv.append("--help")
-
- config = ServerOptions()
try:
config.parseOptions()
except usage.error, ue:
config.opt_help()
print "%s: %s" % (sys.argv[0], ue)
os._exit(1)
+ if config['encrypted']:
+ import getpass
+ config['passphrase'] = getpass.getpass('Passphrase: ')
+ else:
+ config['passphaase'] = None
+ return config
- runApp(config)
+def run():
+ runApp(parseOptions(ServerOptions()))
-------------- next part --------------
# Copyright (C) 2001 Matthew W. Lefkowitz
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of version 2.1 of the GNU Lesser General Public
# License as published by the Free Software Foundation.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
from __future__ import nested_scopes
from twisted.scripts import twistd
from twisted.python import usage
class ServerOptions(twistd.ServerOptions):
synopsis = "Usage: twistctl [options] [start|stop|restart]"
subCommands = [['start', None, usage.Options,
'starts the application requested (default)'],
['stop', None, usage.Options,
'shuts the given application down if it is running'],
['restart',None, usage.Options,
'restarts the application']]
def stopApp(config):
from signal import SIGTERM
from os.path import exists
from time import sleep
twistd.signalApp(config, SIGTERM)
nWait = 0 # processes do not die instantly
while exists(config['pidfile']) and nWait < 20:
sleep(.1)
nWait += 1
def restartApp(config):
stopApp(config)
runApp(config)
def run():
config = twistd.parseOptions(ServerOptions())
cmd = getattr(config,'subCommand','start')
if 'stop' == cmd: return stopApp(config)
if 'restart' == cmd: return restartApp(config)
twistd.runApp(config)
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