Add runafter script.

setup.py

@@ -63,6 +63,7 @@ setup(name=name,
           'pubsubserver = slapos.pubsub:main',
           'pubsubnotifier = slapos.pubsub.notifier:main',
           'logfollower = slapos.logfollower:run',
+          'runafter = slapos.runafter:main',
         ]
       },
     )

slapos/runafter.py

+##############################################################################
+#
+# Copyright (c) 2010 Vifib SARL and Contributors. All Rights Reserved.
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsibility of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# guarantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 3
+# of the License, or (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+#
+##############################################################################
+import argparse
+import os
+import sys
+import signal
+import struct
+
+children = []
+execution_failed = False
+
+def run_executable(executable, redirect_stderr):
+  if redirect_stderr:
+    # Redirect stderr to stdout
+    # and      stderr to devnull
+    stderr_fileno = sys.stderr.fileno()
+    stdout_fileno = sys.stdout.fileno()
+    null_fileno = os.open(os.devnull, os.O_WRONLY)
+
+    os.close(stderr_fileno)
+    os.dup2(stdout_fileno, stderr_fileno)
+    os.dup2(null_fileno, stdout_fileno)
+    os.close(null_fileno)
+  os.execl(executable, executable)
+
+def forkandrun(executable, redirect_stderr):
+  global children
+  try:
+    pid = os.fork()
+    if pid > 0: # Parent process
+      children.append(pid)
+    else: # Children process
+      run_executable(executable, redirect_stderr)
+  except OSError:
+    print >> sys.stderr, "Failed to run %r" % executable
+
+def split_status(status_code):
+  return struct.unpack('BB', struct.pack('H', status_code))
+
+def main():
+  global children, execution_failed
+
+  def sigchld_handler(signum, frame):
+    global children, execution_failed
+    pid, status = os.wait()
+    exitcode, sigcode = split_status(status)
+    if exitcode != 0 or sigcode != 0:
+      execution_failed = True
+    children.remove(pid)
+
+  def sigterm_handler(signum, frame):
+    global children
+    for pid in children:
+      try:
+        os.kill(pid, signal.SIGTERM)
+      except:
+        pass
+    raise SystemExit
+
+  signal.signal(signal.SIGTERM, sigterm_handler)
+  signal.signal(signal.SIGCHLD, sigchld_handler)
+
+  argument_parser = argparse.ArgumentParser(
+    description="Execute binary list of executable after the first one has "
+                "finished. This uses fork and wait for child. Sending a "
+                "SIGTERM to this program will properly send a SIGTERM to its "
+                "children."
+  )
+  argument_parser.add_argument('--stdout', required=False, action='store_true',
+                               help="Redirect stderr on stdout and ignore "
+                                    "stdout.")
+  argument_parser.add_argument('--first-one', '-f', metavar='main',
+                               required=True,
+                               help='First executable to run.')
+  argument_parser.add_argument('executables', metavar='executable', nargs='+')
+  arguments = argument_parser.parse_args()
+
+  forkandrun(arguments.first_one, arguments.stdout)
+  while children:
+    signal.pause()
+  if not execution_failed:
+    for executable in arguments.executables:
+      forkandrun(executable, arguments.stdout)
+    while children:
+      signal.pause()
+  else:
+    if arguments.stdout:
+      output = sys.stdout
+    else:
+      output = sys.stderr
+    print >> output, "Failed to run the first executable."
+
+  if execution_failed:
+    return 1
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())