salmon/utils.py

   1 """
   2 Mostly utility functions Salmon uses internally that don't
   3 really belong anywhere else in the modules.  This module
   4 is kind of a dumping ground, so if you find something that
   5 can be improved feel free to work up a patch.
   6 """
   7 import imp
   8 import importlib
   9 import logging
  10 import os
  11 import sys
  12
  13 from lockfile import pidlockfile
  14 import daemon
  15
  16 from salmon import routing, server
  17
  18 settings = None
  19
  20
  21 def import_settings(boot_also, boot_module="config.boot"):
  22     """Returns the current settings module, there is no harm in calling it
  23     multiple times
  24
  25     The location of the settings module can be control via
  26     ``SALMON_SETTINGS_MODULE``"""
  27     global settings
  28
  29     if settings is None:
  30         settings_module = os.getenv("SALMON_SETTINGS_MODULE", "config.settings")
  31         settings = importlib.import_module(settings_module)
  32
  33     if boot_also:
  34         importlib.import_module(boot_module)
  35
  36     return settings
  37
  38
  39 def daemonize(pid, chdir, chroot, umask, files_preserve=None, do_open=True):
  40     """
  41     Uses python-daemonize to do all the junk needed to make a
  42     server a server.  It supports all the features daemonize
  43     has, except that chroot probably won't work at all without
  44     some serious configuration on the system.
  45     """
  46     logs_dir = os.path.join(chdir, "logs")
  47     pid_dir = os.path.join(chdir, os.path.dirname(pid) or ".")
  48     if chroot:
  49         logs_dir = os.path.join(chroot, logs_dir)
  50         pid_dir = os.path.join(chroot, pid_dir)
  51     if not os.path.exists(logs_dir):
  52         os.mkdir(logs_dir)
  53     if not os.path.exists(pid_dir):
  54         os.mkdir(pid_dir)
  55
  56     context = daemon.DaemonContext()
  57     context.pidfile = pidlockfile.PIDLockFile(pid)
  58     context.stdout = open(os.path.join(logs_dir, "salmon.out"), "a+")
  59     context.stderr = open(os.path.join(logs_dir, "salmon.err"), "a+")
  60     context.files_preserve = files_preserve or []
  61     context.working_directory = os.path.expanduser(chdir)
  62
  63     if chroot:
  64         context.chroot_directory = os.path.expanduser(chroot)
  65     if umask is not None:
  66         context.umask = umask
  67
  68     if do_open:
  69         context.open()
  70
  71     return context
  72
  73
  74 def drop_priv(uid, gid):
  75     """
  76     Changes the uid/gid to the two given, you should give utils.daemonize
  77     0,0 for the uid,gid so that it becomes root, which will allow you to then
  78     do this.
  79     """
  80     logging.debug("Dropping to uid=%d, gid=%d", uid, gid)
  81     daemon.daemon.change_process_owner(uid, gid)
  82     logging.debug("Now running as uid=%d, gid=%d", os.getgid(), os.getuid())
  83
  84
  85 def make_fake_settings(host, port):
  86     """
  87     When running as a logging server we need a fake settings module to work with
  88     since the logging server can be run in any directory, so there may not be
  89     a settings module to import.
  90     """
  91     global settings
  92
  93     if settings is None:
  94         logging.basicConfig(filename="logs/logger.log", level=logging.DEBUG)
  95         routing.Router.load(['salmon.handlers.log', 'salmon.handlers.queue'])
  96         settings = imp.new_module('settings')
  97         settings.receiver = server.SMTPReceiver(host, port)
  98         settings.relay = None
  99         logging.info("Logging mode enabled, will not send email to anyone, just log.")
 100
 101     return settings
 102
 103
 104 def check_for_pid(pid, force):
 105     """Checks if a pid file is there, and if it is sys.exit.  If force given
 106     then it will remove the file and not exit if it's there."""
 107     if os.path.exists(pid):
 108         if not force:
 109             print("PID file %s exists, so assuming Salmon is running.  Give --force to force it to start." % pid)
 110             sys.exit(1)
 111         else:
 112             os.unlink(pid)
 113
 114
 115 def start_server(pid, force, chroot, chdir, uid, gid, umask, settings_loader, debug, daemon_proc):
 116     """
 117     Starts the server by doing a daemonize and then dropping priv
 118     accordingly.  It will only drop to the uid/gid given if both are given.
 119     """
 120     check_for_pid(pid, force)
 121
 122     if not debug and daemon_proc:
 123         daemonize(pid, chdir, chroot, umask, files_preserve=[])
 124
 125     sys.path.append(os.getcwd())
 126
 127     settings = settings_loader()
 128
 129     if uid and gid:
 130         drop_priv(uid, gid)
 131     elif uid or gid:
 132         logging.warning("You probably meant to give a uid and gid, but you gave: uid=%r, gid=%r. "
 133                         "Will not change to any user.", uid, gid)
 134
 135     settings.receiver.start()
 136
 137     if debug:
 138         print("Salmon started in debug mode. ctrl-c to quit...")
 139         import time
 140         try:
 141             while True:
 142                 time.sleep(100000)
 143         except KeyboardInterrupt:
 144             # hard quit, since receiver starts a new thread. dirty but works
 145             os._exit(1)