From 2b095237a634a9865e324b5b46c15b089e64ba67 Mon Sep 17 00:00:00 2001
From: lmr <lmr@592f7852-d20e-0410-864c-8624ca9c26a4>
Date: Wed, 25 May 2011 20:12:12 +0000
Subject: [PATCH] scheduler monitor (monitor_db_babysitter): Add --background
 option

The init script libraries for Red Hat based systems don't contain
the start-stop-daemon function present on /lib/lsb/init-functions,
commonly present on debian/ubuntu boxes. So, in order to implement
a init script for RH-based systems, introduce the --background
option for the scheduler monitor, which will fork it and detach it
from the parent terminal. In order to do that, defer the logging
configuration a little, also modify the interfaces for the logging
config functions of this module a little.

Signed-off-by: James Laska <jlaska@redhat.com>
Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>


git-svn-id: svn://test.kernel.org/autotest/trunk@5380 592f7852-d20e-0410-864c-8624ca9c26a4
---
 scheduler/babysitter_logging_config.py |  7 ++++-
 scheduler/monitor_db_babysitter        | 53 +++++++++++++++++++++++++---------
 2 files changed, 46 insertions(+), 14 deletions(-)

diff --git a/scheduler/babysitter_logging_config.py b/scheduler/babysitter_logging_config.py
index cf2d699c..dde41a85 100644
--- a/scheduler/babysitter_logging_config.py
+++ b/scheduler/babysitter_logging_config.py
@@ -3,8 +3,13 @@ import logging
 from autotest_lib.client.common_lib import logging_config
 
 class BabysitterLoggingConfig(logging_config.LoggingConfig):
+    def __init__(self, use_console=True):
+        self.use_console = use_console
+        super(BabysitterLoggingConfig, self).__init__()
+
     def configure_logging(self):
-        super(BabysitterLoggingConfig, self).configure_logging(use_console=True)
+        super(BabysitterLoggingConfig, self).configure_logging(
+                                                  use_console=self.use_console)
 
         self.add_file_handler(self.get_timestamped_log_name('babysitter'),
                               logging.DEBUG,
diff --git a/scheduler/monitor_db_babysitter b/scheduler/monitor_db_babysitter
index aac6c4e8..4625781d 100755
--- a/scheduler/monitor_db_babysitter
+++ b/scheduler/monitor_db_babysitter
@@ -12,7 +12,11 @@ PAUSE_LENGTH = 60
 STALL_TIMEOUT = 2*60*60
 
 parser = OptionParser()
-parser.add_option("-r", action="store_true", dest="recover")
+parser.add_option("-r", action="store_true", dest="recover",
+                  help=("run recovery mode (implicit after any crash)"))
+parser.add_option("--background", dest="background", action="store_true",
+                  default=False, help=("runs the scheduler monitor on "
+                                       "background"))
 (options, args) = parser.parse_args()
 
 autodir = os.path.abspath(os.path.join(os.path.dirname(__file__), '..'))
@@ -20,15 +24,8 @@ results_dir = os.path.join(autodir, 'results')
 monitor_db_path = os.path.join(autodir, 'scheduler/monitor_db.py')
 recover = (options.recover == True)
 
-# load logging settings
-logging_manager.configure_logging(
-        babysitter_logging_config.BabysitterLoggingConfig())
-
 if len(args) != 0:
-    print "Usage: %s [options]" % __file__
-    print "  -r    Run recovery mode.  (Note: recovery is implicit after"
-    print "        any crash!)"
-    print
+    parser.print_help()
     sys.exit(1)
 
 
@@ -142,17 +139,47 @@ class MonitorProc(SiteMonitorProc):
         log.close()
 
 
-logging.info("initializing")
-
 if os.getuid() == 0:
-    logging.critical("running as root, aborting!")
+    logging.critical("Running as root, aborting!")
     sys.exit(1)
 
 if utils.program_is_alive(monitor_db.BABYSITTER_PID_FILE_PREFIX):
-    logging.critical("monitor_db_babysitter already running, aborting!")
+    logging.critical("Monitor_db_babysitter already running, aborting!")
     sys.exit(1)
+
 utils.write_pid(monitor_db.BABYSITTER_PID_FILE_PREFIX)
 
+if options.background:
+    logging_manager.configure_logging(
+           babysitter_logging_config.BabysitterLoggingConfig(use_console=False))
+
+    # Double fork - see http://code.activestate.com/recipes/66012/
+    try:
+        pid = os.fork()
+        if (pid > 0):
+            sys.exit(0) # exit from first parent
+    except OSError, e:
+        sys.stderr.write("fork #1 failed: (%d) %s\n" % (e.errno, e.strerror))
+        sys.exit(1)
+
+    # Decouple from parent environment
+    os.chdir("/")
+    os.umask(0)
+    os.setsid()
+
+    # Second fork
+    try:
+        pid = os.fork()
+        if (pid > 0):
+            sys.exit(0) # exit from second parent
+    except OSError, e:
+        sys.stderr.write("fork #2 failed: (%d) %s\n" % (e.errno, e.strerror))
+        sys.exit(1)
+else:
+    logging_manager.configure_logging(
+                            babysitter_logging_config.BabysitterLoggingConfig())
+
+
 while True:
     proc = MonitorProc(do_recovery=recover)
     proc.start()
-- 
2.11.4.GIT