VMBuilder.util

1 # 2 # Uncomplicated VM Builder 3 # Copyright (C) 2007-2009 Canonical Ltd. 4 # 5 # See AUTHORS for list of contributors 6 # 7 # This program is free software: you can redistribute it and/or modify 8 # it under the terms of the GNU General Public License version 3, as 9 # published by the Free Software Foundation. 10 # 11 # This program is distributed in the hope that it will be useful, 12 # but WITHOUT ANY WARRANTY; without even the implied warranty of 13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 # GNU General Public License for more details. 15 # 16 # You should have received a copy of the GNU General Public License 17 # along with this program. If not, see <http://www.gnu.org/licenses/>. 18 # 19 # Various utility functions 20 import ConfigParser 21 import errno 22 import fcntl 23 import logging 24 import os.path 25 import select 26 import subprocess 27 import tempfile 28 from exception import VMBuilderException, VMBuilderUserError 29

30 -class NonBlockingFile(object):

31 - def __init__(self, fp, logfunc):

32 self.file = fp 33 self.set_non_blocking() 34 self.buf = '' 35 self.logbuf = '' 36 self.logfunc = logfunc

37

38 - def set_non_blocking(self):

39 flags = fcntl.fcntl(self.file, fcntl.F_GETFL) 40 flags = flags | os.O_NONBLOCK 41 fcntl.fcntl(self.file, fcntl.F_SETFL, flags)

42

43 - def __getattr__(self, attr):

44 if attr == 'closed': 45 return self.file.closed 46 else: 47 raise AttributeError()

48

49 - def process_input(self):

50 data = self.file.read() 51 if data == '': 52 self.file.close() 53 if self.logbuf: 54 self.logfunc(self.logbuf) 55 else: 56 self.buf += data 57 self.logbuf += data 58 while '\n' in self.logbuf: 59 line, self.logbuf = self.logbuf.split('\n', 1) 60 self.logfunc(line)

61

62 -def run_cmd(*argv, **kwargs):

63 """ 64 Runs a command. 65 66 Locale is reset to C to make parsing error messages possible. 67 68 @type stdin: string 69 @param stdin: input to provide to the process on stdin. If None, process' 70 stdin will be attached to /dev/null 71 @type ignore_fail: boolean 72 @param ignore_fail: If True, a non-zero exit code from the command will not 73 cause an exception to be raised. 74 @type env: dict 75 @param env: Dictionary of extra environment variables to set in the new process 76 77 @rtype: string 78 @return: string containing the stdout of the process 79 """ 80 81 env = kwargs.get('env', {}) 82 stdin = kwargs.get('stdin', None) 83 ignore_fail = kwargs.get('ignore_fail', False) 84 args = [str(arg) for arg in argv] 85 logging.debug(args.__repr__()) 86 if stdin: 87 logging.debug('stdin was set and it was a string: %s' % (stdin,)) 88 stdin_arg = subprocess.PIPE 89 else: 90 stdin_arg = file('/dev/null', 'r') 91 proc_env = dict(os.environ) 92 proc_env['LANG'] = 'C' 93 proc_env['LC_ALL'] = 'C' 94 proc_env.update(env) 95 96 try: 97 proc = subprocess.Popen(args, stdin=stdin_arg, stderr=subprocess.PIPE, stdout=subprocess.PIPE, env=proc_env) 98 except OSError, error: 99 if error.errno == errno.ENOENT: 100 raise VMBuilderUserError, "Couldn't find the program '%s' on your system" % (argv[0]) 101 else: 102 raise VMBuilderUserError, "Couldn't launch the program '%s': %s" % (argv[0], error) 103 104 if stdin: 105 proc.stdin.write(stdin) 106 proc.stdin.close() 107 108 mystdout = NonBlockingFile(proc.stdout, logfunc=logging.debug) 109 mystderr = NonBlockingFile(proc.stderr, logfunc=(ignore_fail and logging.debug or logging.info)) 110 111 while not (mystdout.closed and mystderr.closed): 112 # Block until either of them has something to offer 113 fds = select.select([x.file for x in [mystdout, mystderr] if not x.closed], [], [])[0] 114 for fp in [mystderr, mystdout]: 115 if fp.file in fds: 116 fp.process_input() 117 118 status = proc.wait() 119 if not ignore_fail and status != 0: 120 raise VMBuilderException, "Process (%s) returned %d. stdout: %s, stderr: %s" % (args.__repr__(), status, mystdout.buf, mystderr.buf) 121 return mystdout.buf

122

123 -def checkroot():

124 """ 125 Check if we're running as root, and bail out if we're not. 126 """ 127 128 if os.geteuid() != 0: 129 raise VMBuilderUserError("This script must be run as root (e.g. via sudo)")

130

131 -def render_template(plugin, context, tmplname, extra_context=None):

132 # Import here to avoid having to build-dep on python-cheetah 133 from Cheetah.Template import Template 134 searchList = [] 135 if context: 136 searchList.append(extra_context) 137 searchList.append(context) 138 139 # tmpldirs.insert(0,'%s/%%s' % vm.templates) 140 141 tmpldirs = [dir % plugin for dir in context.template_dirs] 142 143 for dir in tmpldirs: 144 tmplfile = '%s/%s.tmpl' % (dir, tmplname) 145 if os.path.exists(tmplfile): 146 t = Template(file=tmplfile, searchList=searchList) 147 output = t.respond() 148 logging.debug('Output from template \'%s\': %s' % (tmplfile, output)) 149 return output 150 151 raise VMBuilderException('Template %s.tmpl not found in any of %s' % (tmplname, ', '.join(tmpldirs)))

152

153 -def call_hooks(context, func, *args, **kwargs):

154 logging.info('Calling hook: %s' % func) 155 logging.debug('(args=%r, kwargs=%r)' % (args, kwargs)) 156 for plugin in context.plugins: 157 logging.debug('Calling %s method in %s plugin.' % (func, plugin.__module__)) 158 try: 159 getattr(plugin, func)(*args, **kwargs) 160 except AttributeError as e: 161 logging.debug('No such method ({}) in context plugin ({})'.format( 162 func, plugin.__module__)) 163 164 for f in context.hooks.get(func, []): 165 logging.debug('Calling %r.' % (f,)) 166 f(*args, **kwargs) 167 168 logging.debug('Calling %s method in context plugin %s.' % (func, context.__module__)) 169 try: 170 getattr(context, func)(*args, **kwargs) 171 except AttributeError as e: 172 logging.debug('No such method ({}) in context plugin ({})'.format( 173 func, plugin.__module__))

174

175 -def tmp_filename(suffix='', tmp_root=None):

176 # There is a risk in using tempfile.mktemp(): it's not recommended 177 # to run vmbuilder on machines with untrusted users. 178 return tempfile.mktemp(suffix=suffix, dir=tmp_root)

179

180 -def tmpdir(suffix='', tmp_root=None):

181 return tempfile.mkdtemp(suffix=suffix, dir=tmp_root)

182

183 -def set_up_tmpfs(tmp_root=None, size=1024):

184 """Sets up a tmpfs storage under `tmp_root` with the size of `size` MB. 185 186 `tmp_root` defaults to tempfile.gettempdir(). 187 """ 188 mount_point = tmpdir('tmpfs', tmp_root) 189 mount_cmd = ["mount", "-t", "tmpfs", 190 "-o", "size=%dM,mode=0770" % int(size), 191 "tmpfs", mount_point ] 192 logging.info('Mounting tmpfs under %s' % mount_point) 193 logging.debug('Executing: %s' % mount_cmd) 194 run_cmd(*mount_cmd) 195 196 return mount_point

197

198 -def clean_up_tmpfs(mount_point):

199 """Unmounts a tmpfs storage under `mount_point`.""" 200 umount_cmd = ["umount", "-t", "tmpfs", mount_point ] 201 logging.info('Unmounting tmpfs from %s' % mount_point) 202 logging.debug('Executing: %s' % umount_cmd) 203 run_cmd(*umount_cmd)

204 205

206 -def get_conf_value(context, confparser, key):

207 confvalue = None 208 try: 209 confvalue = confparser.get('DEFAULT', key) 210 except ConfigParser.NoSectionError: 211 pass 212 except ConfigParser.NoOptionError: 213 pass 214 215 if confparser.has_option(context.arg, key): 216 confvalue = confparser.get(context.arg, key) 217 218 logging.debug('Returning value %s for configuration key %s' % (repr(confvalue), key)) 219 return confvalue

220

221 -def apply_config_files_to_context(config_files, context):

222 confparser = ConfigParser.SafeConfigParser() 223 confparser.read(config_files) 224 225 for (key, setting) in context._config.iteritems(): 226 confvalue = get_conf_value(context, confparser, key) 227 if confvalue: 228 setting.set_value_fuzzy(confvalue)

229

Source Code for Module VMBuilder.util