ecn-robots/vserver.py

r'''Python interface to Linux-VServer for managing hosting systems.
'''
__version__      = '0.2'
__author__       = 'Volker Grabsch'
__author_email__ = 'vog@notjusthosting.com'
__url__          = 'http://www.profv.de/python-vserver/'
__classifiers__  = '''
                   Development Status :: 5 - Production/Stable
                   Environment :: Console
                   Intended Audience :: Developers
                   Intended Audience :: System Administrators
                   License :: OSI Approved :: MIT License
                   Operating System :: POSIX :: Linux
                   Programming Language :: Python
                   Topic :: Software Development :: Libraries :: Python Modules
                   Topic :: System :: Installation/Setup
                   Topic :: System :: Systems Administration
                   Topic :: Utilities
                   '''
__license__      = '''
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject
to the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
'''
import subprocess
import os
import urllib2
import re
import math

class Error(RuntimeError):

    def __init__(self, message_format, *args):
        self._message = message_format % tuple(args)

    def __str__(self):
        return self._message.encode('UTF-8')

class System(object):

    def __init__(self):
        pass

    def read_uri(self, uri):
        f = urllib2.urlopen(uri)
        try:
            return f.read().decode('UTF-8')
        finally:
            f.close()

    def read_binary(self, path):
        if path[0] != u'/':
            raise Error(u'Not an absolute path: %s', path)
        f = file(path.encode('UTF-8'), 'r')
        try:
            return f.read()
        finally:
            f.close()
    def write_binary(self, path, mode, binary):
        if path[0] != u'/':
            raise Error(u'Not an absolute path: %s', path)
        try:
            current_mode = os.stat(path.encode('UTF-8')).st_mode  & 07777
            if current_mode != mode:
                raise Error(u'File already exists with different mode: %s\n'
                            u'\n'
                            u'Current mode:  %04o\n'
                            u'Expected mode: %04o',
                            path, current_mode, mode)
        except OSError, e:
            pass
        fd = os.open(path.encode('UTF-8'), os.O_CREAT | os.O_WRONLY | os.O_TRUNC, mode)
        f = os.fdopen(fd, 'w')
        try:
            f.write(binary)
        finally:
            f.close()
            # set mode again, because os.open() never sets suid/sgid/sticky bits
            os.chmod(path.encode('UTF-8'), mode)

    def run(self, command, input=None, allowed_returncodes=None):
        if isinstance(command, basestring):
            raise Error(u'The command should be given as list, not string: %r',
                        command)
        if input is None:
            stdin = file(os.devnull, 'r')
        else:
            stdin = subprocess.PIPE
            input = input.encode('UTF-8')
        try:
            process = subprocess.Popen(
                [arg.encode('UTF-8') for arg in command],
                bufsize=0,
                stdin=stdin,
                stdout=subprocess.PIPE,
                stderr=subprocess.PIPE,
                close_fds=True,
                shell=False,
                cwd=None,
                env={u'PATH': os.getenv(u'PATH')},
                universal_newlines=False,
            )
        except OSError, e:
            raise Error(u'Command %r: %s', command, e)
        output, error = process.communicate(input)
        output = output.decode('UTF-8')
        error = error.decode('UTF-8')
        returncode = process.returncode
        if allowed_returncodes is None:
            allowed_returncodes = [0]
        if returncode not in allowed_returncodes:
            raise Error(u'Command failed: %r\n\nReturn code: %i\n\nOutput:\n%s\n\nError:\n%s',
                        command, returncode, output.strip('\n'), error.strip('\n'))
        return returncode, output.decode('UTF-8')

    def convert_human(self, secs):
        mins, secs = divmod(secs, 60)
        hours, mins = divmod(mins, 60)
        days, hours = divmod(hours, 24)
        interval = '%d days %d hours %d minutes %d seconds' % (days, hours, mins, secs)
        return interval

    def get_line_value(self, file, tag):
        if os.path.isfile(file):
            with open(file) as f:
                val = f.readline()
                while val:
                    if val.startswith(tag):
                        val=val.replace(tag,'')
                        value = val.strip()
                    val = f.readline()
                return value
        return 'None'

class Host(object):

    def __init__(self):
        self.p = System()

    def vserver_list(self):
        list = os.listdir(u'/etc/vservers/')
        list.remove(u'.defaults')
        list.remove(u'.distributions')
        list.remove(u'lost+found')
        return list

    @property
    def info(self):
        information= {'kernel':'', 'uptime':'' }
        information['kernel'] = os.uname()[2]
        secs = math.ceil(float(self.p.read_binary(u'/proc/uptime').split()[1]))
        information['uptime'] = self.p.convert_human(secs)
        return information

class VServer(object):

    def __init__(self, name):
        self.p = System()
        self._name = name
        self._dirs = {}

    def read_uri(self, uri):
        return self.p.read_uri(uri)

    def _one_line(self, text):
        if text == u'':
            raise Error(u'Empty line.')
        if u'\n' in text[:-1]:
            raise Error(u'Multiple lines where a single line was expected:\n%s', text.strip(u'\n'))
        if text[-1] != u'\n':
            raise Error(u'Incomplete line: %s', text)
        return text[:-1]

    def _path(self, path_type, path):
        if path[0] != u'/':
            raise Error(u'Not an absolute path: %s', path)
        if not self._dirs.has_key(path_type):
            returncode, output = self.p.run([u'vserver-info', self._name, path_type])
            self._dirs[path_type] = self._one_line(output)
        return self._dirs[path_type] + path

    def _read_cfg(self, path):
        return self.p.read_binary(self._path(u'CFGDIR', path)).decode('UTF-8')

    def _write_cfg(self, path, mode, content):
        self.p.write_binary(self._path(u'CFGDIR', path), mode, content.encode('UTF-8'))

    def read_binary(self, path):
        return self.p.read_binary(self._path(u'VDIR', path))
    def write_binary(self, path, mode, binary):
        self.p.write_binary(self._path(u'VDIR', path), mode, binary)

    def read(self, path):
        return self.read_binary(path).decode('UTF-8')

    def write(self, path, mode, content):
        self.write_binary(path, mode, content.encode('UTF-8'))

    def read_one_line(self, path):
        return self._one_line(self.read(path))

    def write_one_line(self, path, mode, line):
        if u'\n' in line:
            raise Error(u'Invalid line break in: %r', line)
        self.write(path, mode, u'%s\n' % (line,))

    def run(self, command, input=None, allowed_returncodes=None):
        return self.p.run([u'vserver', self._name, u'exec'] + command,
                          input, allowed_returncodes)

    def _get_running(self):
        returncode, output = self.p.run([u'vserver', self._name, u'running'],
                                        allowed_returncodes=[0, 1])
        return (returncode == 0)

    def _set_running(self, running):
        if running:
            self.p.run([u'vserver', self._name, u'start'])
        else:
            self.p.run([u'vserver', self._name, u'stop'])

    running = property(_get_running, _set_running)

    @property
    def context(self):
        """Get the context of speciffied vserver."""
        with open(u'/etc/vservers/' + self._name + u'/context') as f:
            ctx = f.read().strip()
        return ctx

    @property
    def load(self):
        """Get the load of specified vserver."""
        fl = u'/proc/virtual/' + self.context + u'/cvirt'
        load = self.p.get_line_value(fl, u'loadavg:')
        return load

    @property
    def uptime(self):
        """Get uptime of the vserver."""
        fl = u'/proc/virtual/' + self.context + u'/cvirt'
        bupx = self.p.get_line_value(fl, u'BiasUptime:')
        if (bupx != 'None'):
            bupx = float(bupx)
            hupx = math.ceil(float(self.p.read_binary(u'/proc/uptime').split()[1]))
            cupx = hupx - bupx
            return self.p.convert_human(cupx)
        return bupx

    def _get_start_on_boot(self):
        try:
            mark = self._read_cfg(u'/apps/init/mark')
        except IOError, e:
            return False
        if mark == u'default\n':
            return True
        elif mark == u'':
            return False
        else:
            raise Error(u'Unexpected init mark: %r', mark)

    def _set_start_on_boot(self, start_on_boot):
        if start_on_boot:
            self._write_cfg(u'/apps/init/mark', 0644, u'default\n')
        else:
            self._write_cfg(u'/apps/init/mark', 0644, u'')

    start_on_boot = property(_get_start_on_boot, _set_start_on_boot)

    def build(self, ip, fqdn, interface, method):
        self.p.run([u'vserver', self._name, u'build',
                    u'--hostname', self._name,
                    u'--interface', interface,
                    u'-m'] + method)
        self.write(u'/etc/hosts', 0644,
            u'%s  %s %s\n' % (ip, fqdn, self._name)
        )
        self._write_cfg(u'/fstab', 0644,
            # disable ramdisk /tmp
            u'none  /proc     proc    defaults        0 0\n'
            u'none  /dev/pts  devpts  gid=5,mode=620  0 0\n'
        )
        self.running = True

    def delete(self):
        self.p.run([u'vserver', self._name, u'delete'],
                   input=u'Y\n')
def _test():
    test = Host()
    print 'Host kernel is',test.info['kernel']
    print 'Uptime of host is', test.info['uptime']
    lst = test.vserver_list()
    print '%-10s %-20s %-10s %-20s %-20s' % ('Context', 'Name', 'Running', 'Load', 'Uptime')
    for i in range(len(lst)):
        vs = VServer(lst[i])
        print '%-10s %-20s %-10s %-20s %-20s' % (vs.context, lst[i], vs.running, vs.load, vs.uptime)

if __name__ == '__main__':
    _test()