support 'power_state' cloud-config for specifying shutdown

this adds 'power-state-change' config module that allows the user to
specify in cloud-config syntax that a system reboot or shutdown should occur
after cloud-init is done.

1 files changed, 155 insertions, 0 deletions

diff --git a/cloudinit/config/cc_power_state_change.py b/cloudinit/config/cc_power_state_change.py
new file mode 100644
index 00000000..aefa3aff
--- /dev/null
+++ b/cloudinit/config/cc_power_state_change.py
@@ -0,0 +1,155 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2011 Canonical Ltd.
+#
+#    Author: Scott Moser <scott.moser@canonical.com>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License version 3, as
+#    published by the Free Software Foundation.
+#
+#    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, see <http://www.gnu.org/licenses/>.
+
+from cloudinit.settings import PER_INSTANCE
+from cloudinit import util
+
+import errno
+import os
+import re
+import subprocess
+import time
+
+frequency = PER_INSTANCE
+
+EXIT_FAIL = 254
+
+
+def handle(_name, cfg, _cloud, log, _args):
+
+    try:
+        (args, timeout) = load_power_state(cfg)
+        if args is None:
+            log.debug("no power_state provided. doing nothing")
+            return
+    except Exception as e:
+        log.warn("%s Not performing power state change!" % str(e))
+        return
+
+    mypid = os.getpid()
+    cmdline = util.load_file("/proc/%s/cmdline" % mypid)
+
+    if not cmdline:
+        log.warn("power_state: failed to get cmdline of current process")
+        return
+
+    devnull_fp = open(os.devnull, "w")
+
+    log.debug("After pid %s ends, will execute: %s" % (mypid, ' '.join(args)))
+
+    util.fork_cb(run_after_pid_gone, mypid, cmdline, timeout, log, execmd,
+                 [args, devnull_fp])
+
+
+def load_power_state(cfg):
+    # returns a tuple of shutdown_command, timeout
+    # shutdown_command is None if no config found
+    pstate = cfg.get('power_state')
+
+    if pstate is None:
+        return (None, None)
+
+    if not isinstance(pstate, dict):
+        raise TypeError("power_state is not a dict.")
+
+    opt_map = {'halt': '-H', 'poweroff': '-P', 'reboot': '-r'}
+
+    mode = pstate.get("mode")
+    if mode not in opt_map:
+        raise TypeError("power_state[mode] required, must be one of: %s." %
+                        ','.join(opt_map.keys()))
+
+    delay = pstate.get("delay", "now")
+    if delay != "now" and not re.match("\+[0-9]+", delay):
+        raise TypeError("power_state[delay] must be 'now' or '+m' (minutes).")
+
+    args = ["shutdown", opt_map[mode], delay]
+    if pstate.get("message"):
+        args.append(pstate.get("message"))
+
+    try:
+        timeout = float(pstate.get('timeout', 30.0))
+    except ValueError:
+        raise ValueError("failed to convert timeout '%s' to float." %
+                         pstate['timeout'])
+
+    return (args, timeout)
+
+
+def doexit(sysexit):
+    os._exit(sysexit)  # pylint: disable=W0212
+
+
+def execmd(exe_args, output=None, data_in=None):
+    try:
+        proc = subprocess.Popen(exe_args, stdin=subprocess.PIPE,
+                                stdout=output, stderr=subprocess.STDOUT)
+        proc.communicate(data_in)
+        ret = proc.returncode
+    except Exception:
+        doexit(EXIT_FAIL)
+    doexit(ret)
+
+
+def run_after_pid_gone(pid, pidcmdline, timeout, log, func, args):
+    # wait until pid, with /proc/pid/cmdline contents of pidcmdline
+    # is no longer alive.  After it is gone, or timeout has passed
+    # execute func(args)
+    msg = None
+    end_time = time.time() + timeout
+
+    cmdline_f = "/proc/%s/cmdline" % pid
+
+    def fatal(msg):
+        if log:
+            log.warn(msg)
+        doexit(EXIT_FAIL)
+
+    known_errnos = (errno.ENOENT, errno.ESRCH)
+
+    while True:
+        if time.time() > end_time:
+            msg = "timeout reached before %s ended" % pid
+            break
+
+        try:
+            cmdline = ""
+            with open(cmdline_f) as fp:
+                cmdline = fp.read()
+            if cmdline != pidcmdline:
+                msg = "cmdline changed for %s [now: %s]" % (pid, cmdline)
+                break
+
+        except IOError as ioerr:
+            if ioerr.errno in known_errnos:
+                msg = "pidfile '%s' gone [%d]" % (cmdline_f, ioerr.errno)
+            else:
+                fatal("IOError during wait: %s" % ioerr)
+            break
+
+        except Exception as e:
+            fatal("Unexpected Exception: %s" % e)
+
+        time.sleep(.25)
+
+    if not msg:
+        fatal("Unexpected error in run_after_pid_gone")
+
+    if log:
+        log.debug(msg)
+    func(*args)