scripts/wrap-job

   1 #!/usr/bin/python
   2 """
   3 Wrap a command, setuid/setgid, change directory to the reddit
   4 code, and send output to syslog.
   5
   6 The following environment variables may be used to control
   7 the environment the wrapped command runs in:
   8
   9 REDDIT_USER
  10
  11     The user to run the job as. Defaults to "reddit".
  12
  13 REDDIT_GROUP
  14
  15     The group to run the job as. Defaults to $REDDIT_USER.
  16
  17 REDDIT_ROOT
  18
  19     The root directory of the reddit package. It's where the makefile lives.
  20
  21 REDDIT_LOG_FACILITY
  22
  23     The syslog facility to write messages to.
  24 """
  25
  26 import os
  27 import sys
  28 import grp
  29 import pwd
  30 import syslog
  31 import subprocess
  32
  33
  34 CONSUMER_PREFIX = "reddit-consumer-"
  35
  36
  37 # drop permissions
  38 user = os.environ.get("REDDIT_USER", "reddit")
  39 group = os.environ.get("REDDIT_GROUP", user)
  40 uid = pwd.getpwnam(user).pw_uid
  41 gid = grp.getgrnam(group).gr_gid
  42 os.setgroups([])
  43 os.setgid(gid)
  44 os.setuid(uid)
  45
  46 # change directory to the reddit code root
  47 root = os.environ.get("REDDIT_ROOT", "/opt/reddit/lib/public/r2")
  48 os.chdir(root)
  49
  50 # configure syslog
  51 job_name = os.environ.get("UPSTART_JOB", "-".join(sys.argv[1:]))
  52 if job_name.startswith(CONSUMER_PREFIX):
  53     # consumers are a bit different from crons, while crons want an
  54     # ident of reddit-job-JOBNAME, we want consumers to have an ident
  55     # of CONSUMERNAME_INSTANCE
  56     job_name = (job_name[len(CONSUMER_PREFIX):] +
  57                 "_" +
  58                 os.environ.get("UPSTART_INSTANCE", ""))
  59 facility = getattr(syslog, "LOG_" + os.environ.get("REDDIT_LOG_FACILITY", "CRON"))
  60 syslog.openlog(ident=job_name, facility=facility)
  61
  62 # run the wrapped command
  63 child = subprocess.Popen(sys.argv[1:],
  64                          stdout=subprocess.PIPE,
  65                          stderr=subprocess.STDOUT,
  66                          bufsize=1)
  67
  68 # write out to syslog
  69 while True:
  70     line = child.stdout.readline()
  71
  72     if not line:
  73         break
  74
  75     line = line.rstrip('\n')
  76     syslog.syslog(syslog.LOG_NOTICE, line)
  77     print line
  78
  79 # our success depends on our child's success
  80 child.wait()
  81 sys.exit(child.returncode)