#!/usr/bin/python
#

# Copyright (C) 2006, 2007, 2010, 2011 Google Inc.
#
# 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 2 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., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.

"""Run an executable on a list of hosts.

Script to serially run an executable on a list of hosts via ssh
with password auth as root. If the provided log dir does not yet
exist, it will try to create it.

Implementation:
 - the main process spawns up to batch_size children, which:
 - connects to the remote host via ssh as root
 - uploads the executable with a random name to /tmp via sftp
 - chmod 500s it
 - via ssh: chdirs into the upload directory and runs the script
 - deletes it
 - writes status messages and all output to one logfile per host
 - the main process gathers then the status of the children and
   reports the success/failure ratio
 - entire script can be aborted with Ctrl-C

Security considerations:
 - the root password for the remote hosts is stored in memory for the
   runtime of the script
 - the executable to be run on the remote host is handled the following way:
   - try to create a random directory with permissions 700 on the
     remote host, abort furter processing on this host if this failes
   - upload the executable with to a random filename in that directory
   - set executable permissions to 500
   - run the executable
   - delete the execuable and the directory on the remote host

"""

# pylint: disable=C0103
# C0103: Invalid name ganeti-listrunner

import errno
import optparse
import getpass
import logging
import os
import random
import select
import socket
import sys
import time
import traceback

import paramiko


REMOTE_PATH_BASE = "/tmp/listrunner"

USAGE = ("%prog -l logdir {-c command | -x /path/to/file} [-b batch_size]"
         " {-f hostfile|-h hosts} [-u username]"
         " [-p password_file | -A]")


def LogDirUseable(logdir):
  """Ensure log file directory is available and usable."""
  testfile = "%s/test-%s-%s.deleteme" % (logdir, random.random(),
                                         random.random())
  try:
    os.mkdir(logdir)
  except OSError, err:
    if err.errno != errno.EEXIST:
      raise
  try:
    logtest = open(testfile, "aw")
    logtest.writelines("log file writeability test\n")
    logtest.close()
    os.unlink(testfile)
    return True
  except (OSError, IOError):
    return False


def GetTimeStamp(timestamp=None):
  """Return ISO8601 timestamp.

  Returns ISO8601 timestamp, optionally expects a time.localtime() tuple
  in timestamp, but will use the current time if this argument is not
  supplied.
  """
  if timestamp is None:
    timestamp = time.localtime()

  isotime = time.strftime("%Y-%m-%dT%H:%M:%S", timestamp)
  return isotime


def PingByTcp(target, port, timeout=10, live_port_needed=False, source=None):
  """Simple ping implementation using TCP connect(2).

  Try to do a TCP connect(2) from an optional source IP to the
  specified target IP and the specified target port. If the optional
  parameter live_port_needed is set to true, requires the remote end
  to accept the connection. The timeout is specified in seconds and
  defaults to 10 seconds. If the source optional argument is not
  passed, the source address selection is left to the kernel,
  otherwise we try to connect using the passed address (failures to
  bind other than EADDRNOTAVAIL will be ignored).

  """
  sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

  success = False

  if source is not None:
    try:
      sock.bind((source, 0))
    except socket.error, (errcode):
      if errcode == errno.EADDRNOTAVAIL:
        success = False

  sock.settimeout(timeout)

  try:
    sock.connect((target, port))
    sock.close()
    success = True
  except socket.timeout:
    success = False
  except socket.error, (errcode):
    success = (not live_port_needed) and (errcode == errno.ECONNREFUSED)

  return success


def GetHosts(hostsfile):
  """Return list of hosts from hostfile.

  Reads the hostslist file and returns a list of hosts.
  Expects the hostslist file to contain one hostname per line.

  """
  try:
    datafile = open(hostsfile, "r")
  except IOError, msg:
    print "Failed to open hosts file %s: %s" % (hostsfile, msg)
    sys.exit(2)

  hosts = datafile.readlines()
  datafile.close()

  return hosts


def WriteLog(message, logfile):
  """Writes message, terminated by newline, to logfile."""
  try:
    logfile = open(logfile, "aw")
  except IOError, msg:
    print "failed to open log file %s: %s" % (logfile, msg)
    print "log message was: %s" % message
    sys.exit(1)  # no being able to log is critical
  try:
    timestamp = GetTimeStamp()
    logfile.writelines("%s %s\n" % (timestamp, message))
    logfile.close()
  except IOError, msg:
    print "failed to write to logfile %s: %s" % (logfile, msg)
    print "log message was: %s" % message
    sys.exit(1)  # no being able to log is critical


def GetAgentKeys():
  """Tries to get a list of ssh keys from an agent."""
  try:
    agent = paramiko.Agent()
    return list(agent.get_keys())
  except paramiko.SSHException:
    return []


def SetupSshConnection(host, username, password, use_agent, logfile):
  """Setup the ssh connection used for all later steps.

  This function sets up the ssh connection that will be used both
  for upload and remote command execution.

  On success, it will return paramiko.Transport object with an
  already logged in session. On failure, False will be returned.

  """
  # check if target is willing to talk to us at all
  if not PingByTcp(host, 22, live_port_needed=True):
    WriteLog("ERROR: FAILURE_NOT_REACHABLE", logfile)
    print "  - ERROR: host not reachable on 22/tcp"
    return False

  if use_agent:
    keys = GetAgentKeys()
  else:
    keys = []
  all_kwargs = [{"pkey": k} for k in keys]
  all_desc = ["key %d" % d for d in range(len(keys))]
  if password is not None:
    all_kwargs.append({"password": password})
    all_desc.append("password")

  # deal with logging out of paramiko.transport
  handler = None

  for desc, kwargs in zip(all_desc, all_kwargs):
    try:
      transport = paramiko.Transport((host, 22))

      # only try to setup the logging handler once
      if not handler:
        handler = logging.StreamHandler()
        handler.setLevel(logging.ERROR)
        log = logging.getLogger(transport.get_log_channel())
        log.addHandler(handler)

      transport.connect(username=username, **kwargs) # pylint: disable=W0142
      WriteLog("ssh connection established using %s" % desc, logfile)
      # strange ... when establishing the session and the immediately
      # setting up the channels for sftp & shell from that, it sometimes
      # fails, but waiting 1 second after session setup makes it always work
      # time.sleep(1)
      # FIXME apparently needfull to give sshd some time
      return transport
    except (socket.gaierror, socket.error, paramiko.SSHException):
      continue

  methods = ", ".join(all_desc)
  WriteLog("ERROR: FAILURE_CONNECTION_SETUP (tried %s) " % methods, logfile)
  WriteLog("aborted", logfile)
  print "  - ERROR: connection setup failed (tried %s)" % methods

  return False


def UploadFiles(connection, executable, filelist, logfile):
  """Uploads the specified files via sftp.

  Uploads the specified files to a random, freshly created directory with
  a temporary name under /tmp. All uploaded files are chmod 0400 after upload
  with the exception of executable, with is chmod 500.

  Upon success, returns the absolute path to the remote upload directory,
  but will return False upon failure.
  """
  remote_dir = "%s.%s-%s" % (REMOTE_PATH_BASE,
                             random.random(), random.random())

  try:
    sftp = paramiko.SFTPClient.from_transport(connection)
    sftp.mkdir(remote_dir, mode=0700)
    for item in filelist:
      remote_file = "%s/%s" % (remote_dir, os.path.basename(item))
      WriteLog("uploading %s to remote %s" % (item, remote_file), logfile)
      sftp.put(item, remote_file)
      if item == executable:
        sftp.chmod(remote_file, 0500)
      else:
        sftp.chmod(remote_file, 0400)
    sftp.close()
  except IOError, err:
    WriteLog("ERROR: FAILURE_UPLOAD: %s" % err, logfile)
    return False

  return remote_dir


def CleanupRemoteDir(connection, upload_dir, filelist, logfile):
  """Cleanes out and removes the remote work directory."""
  try:
    sftp = paramiko.SFTPClient.from_transport(connection)
    for item in filelist:
      fullpath = "%s/%s" % (upload_dir, os.path.basename(item))
      WriteLog("removing remote %s" % fullpath, logfile)
      sftp.remove(fullpath)
    sftp.rmdir(upload_dir)
    sftp.close()
  except IOError, err:
    WriteLog("ERROR: FAILURE_CLEANUP: %s" % err, logfile)
    return False

  return True


def RunRemoteCommand(connection, command, logfile):
  """Execute the command via ssh on the remote host."""
  session = connection.open_session()
  session.setblocking(0)

  # the following dance is needed because paramiko changed APIs:
  # from returning True/False for success to always returning None
  # and throwing an exception in case of problems.
  # And I want to support both the old and the new API.
  result = True  # being optimistic here, I know
  message = None
  try:
    if session.exec_command("%s 2>&1" % command) is False:
      result = False
  except paramiko.SSHException, message:
    result = False

  if not result:
    WriteLog("ERROR: FAILURE_COMMAND_EXECUTION: %s" % message, logfile)
    return False

   ### Read when data is available
  output = ""
  while select.select([session], [], []):
    try:
      data = session.recv(1024)
    except socket.timeout, err:
      data = None
      WriteLog("FAILED: socket.timeout %s" % err, logfile)
    except socket.error, err:
      data = None
      WriteLog("FAILED: socket.error %s" % err, logfile)
    if not data:
      break
    output += data
    select.select([], [], [], .1)

  WriteLog("SUCCESS: command output follows", logfile)
  for line in output.splitlines():
    WriteLog("output = %s" % line, logfile)
  WriteLog("command execution completed", logfile)
  session.close()

  return True


def HostWorker(logdir, username, password, use_agent, hostname,
               executable, exec_args, command, filelist):
  """Per-host worker.

  This function does not return - it's the main code of the childs,
  which exit at the end of this function. The exit code 0 or 1 will be
  interpreted by the parent.

  @param logdir: the directory where the logfiles must be created
  @param username: SSH username
  @param password: SSH password
  @param use_agent: whether we should instead use an agent
  @param hostname: the hostname to connect to
  @param executable: the executable to upload, if not None
  @param exec_args: Additional arguments for executable
  @param command: the command to run
  @param filelist: auxiliary files to upload

  """
  # in the child/worker process
  logfile = "%s/%s.log" % (logdir, hostname)
  print "%s - starting" % hostname
  result = 0  # optimism, I know
  try:
    connection = SetupSshConnection(hostname, username,
                                    password, use_agent, logfile)
    if connection is not False:
      if executable is not None:
        print "  %s: uploading files" % hostname
        upload_dir = UploadFiles(connection, executable,
                                 filelist, logfile)
        command = ("cd %s && ./%s" %
                   (upload_dir, os.path.basename(executable)))
        if exec_args:
          command += " %s" % exec_args
      print "  %s: executing remote command" % hostname
      cmd_result = RunRemoteCommand(connection, command, logfile)
      if cmd_result is True:
        print "  %s: remote command execution successful" % hostname
      else:
        print ("  %s: remote command execution failed,"
               " check log for details" % hostname)
        result = 1
      if executable is not None:
        print "  %s: cleaning up remote work dir" % hostname
        cln_result = CleanupRemoteDir(connection, upload_dir,
                                      filelist, logfile)
        if cln_result is False:
          print ("  %s: remote work dir cleanup failed, check"
                 " log for details" % hostname)
          result = 1
      connection.close()
    else:
      print "  %s: connection setup failed, skipping" % hostname
      result = 1
  except KeyboardInterrupt:
    print "  %s: received KeyboardInterrupt, aborting" % hostname
    WriteLog("ERROR: ABORT_KEYBOARD_INTERRUPT", logfile)
    result = 1
  except Exception, err:
    result = 1
    trace = traceback.format_exc()
    msg = "ERROR: UNHANDLED_EXECPTION_ERROR: %s\nTrace: %s" % (err, trace)
    WriteLog(msg, logfile)
    print "  %s: %s" % (hostname, msg)
  # and exit with exit code 0 or 1, so the parent can compute statistics
  sys.exit(result)


def LaunchWorker(child_pids, logdir, username, password, use_agent, hostname,
                 executable, exec_args, command, filelist):
  """Launch the per-host worker.

  Arguments are the same as for HostWorker, except for child_pids,
  which is a dictionary holding the pid-to-hostname mapping.

  """
  hostname = hostname.rstrip("\n")
  pid = os.fork()
  if pid > 0:
    # controller just record the pids
    child_pids[pid] = hostname
  else:
    HostWorker(logdir, username, password, use_agent, hostname,
               executable, exec_args, command, filelist)


def ParseOptions():
  """Parses the command line options.

  In case of command line errors, it will show the usage and exit the
  program.

  @return: the options in a tuple

  """
  # resolve because original used -h for hostfile, which conflicts
  # with -h for help
  parser = optparse.OptionParser(usage="\n%s" % USAGE,
                                 conflict_handler="resolve")

  parser.add_option("-l", dest="logdir", default=None,
                    help="directory to write logfiles to")
  parser.add_option("-x", dest="executable", default=None,
                    help="executable to run on remote host(s)",)
  parser.add_option("-f", dest="hostfile", default=None,
                    help="hostlist file (one host per line)")
  parser.add_option("-h", dest="hostlist", default=None, metavar="HOSTS",
                    help="comma-separated list of hosts or single hostname",)
  parser.add_option("-a", dest="auxfiles", action="append", default=[],
                    help="optional auxiliary file to upload"
                    " (can be given multiple times)",
                    metavar="FILE")
  parser.add_option("-c", dest="command", default=None,
                    help="shell command to run on remote host(s)")
  parser.add_option("-b", dest="batch_size", default=15, type="int",
                    help="batch-size, how many hosts to process"
                    " in parallel [15]")
  parser.add_option("-u", dest="username", default="root",
                    help="username used to connect [root]")
  parser.add_option("-p", dest="password", default=None,
                    help="password used to authenticate (when not"
                    " using an agent)")
  parser.add_option("-A", dest="use_agent", default=False, action="store_true",
                    help="instead of password, use keys from an SSH agent")
  parser.add_option("--args", dest="exec_args", default=None,
                    help="Arguments to be passed to executable (-x)")

  opts, args = parser.parse_args()

  if opts.executable and opts.command:
    parser.error("Options -x and -c conflict with each other")
  if not (opts.executable or opts.command):
    parser.error("One of -x and -c must be given")
  if opts.command and opts.exec_args:
    parser.error("Can't specify arguments when using custom command")
  if not opts.logdir:
    parser.error("Option -l is required")
  if opts.hostfile and opts.hostlist:
    parser.error("Options -f and -h conflict with each other")
  if not (opts.hostfile or opts.hostlist):
    parser.error("One of -f or -h must be given")
  if args:
    parser.error("This program doesn't take any arguments, passed in: %s" %
                 ", ".join(args))

  return (opts.logdir, opts.executable, opts.exec_args,
          opts.hostfile, opts.hostlist,
          opts.command, opts.use_agent, opts.auxfiles, opts.username,
          opts.password, opts.batch_size)


def main():
  """main."""
  (logdir, executable, exec_args, hostfile, hostlist,
   command, use_agent, auxfiles, username,
   password, batch_size) = ParseOptions()

  ### Unbuffered sys.stdout
  sys.stdout = os.fdopen(1, "w", 0)

  if LogDirUseable(logdir) is False:
    print "ERROR: cannot create logfiles in dir %s, aborting" % logdir
    sys.exit(1)

  if use_agent:
    pass
  elif password:
    try:
      fh = file(password)
      pwvalue = fh.readline().strip()
      fh.close()
    except IOError, e:
      print "error: can not read in from password file %s: %s" % (password, e)
      sys.exit(1)
    password = pwvalue
  else:
    password = getpass.getpass("%s's password for all nodes: " % username)

  if hostfile:
    hosts = GetHosts(hostfile)
  else:
    if "," in hostlist:
      hostlist = hostlist.rstrip(",")  # commandline robustness
      hosts = hostlist.split(",")
    else:
      hosts = [hostlist]

  successes = failures = 0

  filelist = auxfiles[:]
  filelist.append(executable)

  # initial batch
  batch = hosts[:batch_size]
  hosts = hosts[batch_size:]
  child_pids = {}
  for hostname in batch:
    LaunchWorker(child_pids, logdir, username, password, use_agent, hostname,
                 executable, exec_args, command, filelist)

  while child_pids:
    pid, status = os.wait()
    hostname = child_pids.pop(pid, "<unknown host>")
    print "  %s: done (in parent)" % hostname
    if os.WIFEXITED(status) and os.WEXITSTATUS(status) == 0:
      successes += 1
    else:
      failures += 1
    if hosts:
      LaunchWorker(child_pids, logdir, username, password, use_agent,
                   hosts.pop(0), executable, exec_args, command, filelist)

  print
  print "All done, %s successful and %s failed hosts" % (successes, failures)

  sys.exit(0)


if __name__ == "__main__":
  try:
    main()
  except KeyboardInterrupt:
    print "Received KeyboardInterrupt, aborting"
    sys.exit(1)