X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=accounts.py;h=47e7af5a39d77a49218a474961510610be4899fd;hb=refs%2Fheads%2F1.5;hp=b22a4ba95304f8227fe560e5fc7649bcd99c4a34;hpb=aac3e5d7c3443d6e1cb33525aefad35be5fe077a;p=nodemanager.git diff --git a/accounts.py b/accounts.py index b22a4ba..47e7af5 100644 --- a/accounts.py +++ b/accounts.py @@ -1,3 +1,25 @@ +"""Functionality common to all account classes. + +Each subclass of Account must provide five methods: create() and +destroy(), which are static; configure(), start(), and stop(), which +are not. configure(), which takes a record as its only argument, does +things like set up ssh keys. In addition, an Account subclass must +provide static member variables SHELL, which contains the unique shell +that it uses; and TYPE, a string that is used by the account creation +code. For no particular reason, TYPE is divided hierarchically by +periods; at the moment the only convention is that all sliver accounts +have type that begins with sliver. + +There are any number of race conditions that may result from the fact +that account names are not unique over time. Moreover, it's a bad +idea to perform lengthy operations while holding the database lock. +In order to deal with both of these problems, we use a worker thread +for each account name that ever exists. On 32-bit systems with large +numbers of accounts, this may cause the NM process to run out of +*virtual* memory! This problem may be remedied by decreasing the +maximum stack size. +""" + import Queue import os import pwd @@ -7,42 +29,70 @@ import logger import tools -_name_worker_lock = threading.Lock() -_name_worker = {} +# When this variable is true, start after any ensure_created +Startingup = False +# Cumulative delay for starts when Startingup is true +csd_lock = threading.Lock() +cumstartdelay = 0 -def all(): - pw_ents = pwd.getpwall() - for pw_ent in pw_ents: - if pw_ent[6] in acct_class_by_shell: - yield acct_class_by_shell[pw_ent[6]].TYPE, pw_ent[0] +# shell path -> account class association +shell_acct_class = {} +# account type -> account class association +type_acct_class = {} -def get(name): - _name_worker_lock.acquire() - try: - if name not in _name_worker: _name_worker[name] = Worker(name) - return _name_worker[name] - finally: _name_worker_lock.release() +def register_class(acct_class): + """Call once for each account class. This method adds the class to the dictionaries used to look up account classes by shell and type.""" + shell_acct_class[acct_class.SHELL] = acct_class + type_acct_class[acct_class.TYPE] = acct_class -def install_ssh_keys(rec): - """Write to 's authorized_keys file.""" - dot_ssh = '/home/%s/.ssh' % rec['name'] - def do_installation(): - if not os.access(dot_ssh, os.F_OK): os.mkdir(dot_ssh) - tools.write_file(dot_ssh + '/authorized_keys', - lambda thefile: thefile.write(rec['ssh_keys'])) - logger.log('%s: installing ssh keys' % rec['name']) - tools.fork_as(rec['name'], do_installation) +# private account name -> worker object association and associated lock +name_worker_lock = threading.Lock() +name_worker = {} +def allpwents(): + return [pw_ent for pw_ent in pwd.getpwall() if pw_ent[6] in shell_acct_class] -TYPES = [] -acct_class_by_shell = {} -acct_class_by_type = {} +def all(): + """Return the names of all accounts on the system with recognized shells.""" + return [pw_ent[0] for pw_ent in allpwents()] -def register_account_type(acct_class): - TYPES.append(acct_class.TYPE) - acct_class_by_shell[acct_class.SHELL] = acct_class - acct_class_by_type[acct_class.TYPE] = acct_class +def get(name): + """Return the worker object for a particular username. If no such object exists, create it first.""" + name_worker_lock.acquire() + try: + if name not in name_worker: name_worker[name] = Worker(name) + return name_worker[name] + finally: name_worker_lock.release() + + +class Account: + def __init__(self, rec): + self.name = rec['name'] + self.keys = '' + self.initscriptchanged = False + self.configure(rec) + + @staticmethod + def create(name, vref = None): abstract + @staticmethod + def destroy(name): abstract + + def configure(self, rec): + """Write to my authorized_keys file.""" + new_keys = rec['keys'] + if new_keys != self.keys: + self.keys = new_keys + dot_ssh = '/home/%s/.ssh' % self.name + def do_installation(): + if not os.access(dot_ssh, os.F_OK): os.mkdir(dot_ssh) + os.chmod(dot_ssh, 0700) + tools.write_file(dot_ssh + '/authorized_keys', lambda f: f.write(new_keys)) + logger.log('%s: installing ssh keys' % self.name) + tools.fork_as(self.name, do_installation) + + def start(self, delay=0): pass + def stop(self): pass class Worker: @@ -51,38 +101,46 @@ class Worker: _destroy_sem = threading.Semaphore(1) def __init__(self, name): - self.name = name - self._acct = None + self.name = name # username + self._acct = None # the account object currently associated with this worker + # task list + # outsiders request operations by putting (fn, args...) tuples on _q + # the worker thread (created below) will perform these operations in order self._q = Queue.Queue() tools.as_daemon_thread(self._run) def ensure_created(self, rec): - self._q.put((self._ensure_created, tools.deepcopy(rec))) + """Cause the account specified by to exist if it doesn't already.""" + self._q.put((self._ensure_created, rec.copy(), Startingup)) - def _ensure_created(self, rec): + def _ensure_created(self, rec, startingup): curr_class = self._get_class() - next_class = acct_class_by_type[rec['account_type']] + next_class = type_acct_class[rec['type']] if next_class != curr_class: self._destroy(curr_class) self._create_sem.acquire() - try: next_class.create(self.name) + try: next_class.create(self.name, rec['vref']) finally: self._create_sem.release() - self._make_acct_obj() - self._acct.configure(rec) - if next_class != curr_class: self._acct.start() + if not isinstance(self._acct, next_class): self._acct = next_class(rec) + else: self._acct.configure(rec) + if startingup: + csd_lock.acquire() + global cumstartdelay + delay = cumstartdelay + cumstartdelay += 2 + csd_lock.release() + self._acct.start(delay=delay) + elif next_class != curr_class or self._acct.initscriptchanged: + self._acct.start() def ensure_destroyed(self): self._q.put((self._ensure_destroyed,)) def _ensure_destroyed(self): self._destroy(self._get_class()) - def start(self): self._q.put((self._start,)) - def _start(self): - self._make_acct_obj() - self._acct.start() + def start(self, delay=0): self._q.put((self._start, delay)) + def _start(self, d): self._acct.start(delay=d) def stop(self): self._q.put((self._stop,)) - def _stop(self): - self._make_acct_obj() - self._acct.stop() + def _stop(self): self._acct.stop() def _destroy(self, curr_class): self._acct = None @@ -94,16 +152,13 @@ class Worker: def _get_class(self): try: shell = pwd.getpwnam(self.name)[6] except KeyError: return None - return acct_class_by_shell[shell] - - def _make_acct_obj(self): - curr_class = self._get_class() - if not isinstance(self._acct, curr_class): - self._acct = curr_class(self.name) + return shell_acct_class[shell] def _run(self): + """Repeatedly pull commands off the queue and execute. If memory usage becomes an issue, it might be wise to terminate after a while.""" while True: try: cmd = self._q.get() cmd[0](*cmd[1:]) - except: logger.log_exc() + except: + logger.log_exc(self.name)