def __init__(self, nsname, *argv, **kwarg): ''' The only differences from the `subprocess.Popen` init are: * `nsname` -- network namespace name * `flags` keyword argument All other arguments are passed directly to `subprocess.Popen`. Flags usage samples. Create a network namespace, if it doesn't exist yet:: import os nsp = NSPopen('nsname', ['command'], flags=os.O_CREAT) Create a network namespace only if it doesn't exist, otherwise fail and raise an exception:: import os nsp = NSPopen('nsname', ['command'], flags=os.O_CREAT | os.O_EXCL) ''' # create a child self.nsname = nsname if 'flags' in kwarg: self.flags = kwarg.pop('flags') else: self.flags = 0 self.channel_out = MpQueue() self.channel_in = MpQueue() self.lock = threading.Lock() self.released = False self.server = MpProcess(target=NSPopenServer, args=(self.nsname, self.flags, self.channel_out, self.channel_in, argv, kwarg)) # start the child and check the status self.server.start() response = self.channel_in.get() if isinstance(response, Exception): self.server.join() raise response else: atexit.register(self.release)
class NSPopen(NSPopenBase, ObjNS): ''' A proxy class to run `Popen()` object in some network namespace. Sample to run `ip ad` command in `nsname` network namespace:: nsp = NSPopen('nsname', ['ip', 'ad'], stdout=subprocess.PIPE) print(nsp.communicate()) nsp.wait() nsp.release() The `NSPopen` class was intended to be a drop-in replacement for the `Popen` class, but there are still some important differences. The `NSPopen` object implicitly spawns a child python process to be run in the background in a network namespace. The target process specified as the argument of the `NSPopen` will be started in its turn from this child. Thus all the fd numbers of the running `NSPopen` object are meaningless in the context of the main process. Trying to operate on them, one will get 'Bad file descriptor' in the best case or a system call working on a wrong file descriptor in the worst case. A possible solution would be to transfer file descriptors between the `NSPopen` object and the main process, but it is not implemented yet. The process' diagram for `NSPopen('test', ['ip', 'ad'])`:: +---------------------+ +--------------+ +------------+ | main python process |<--->| child python |<--->| netns test | | NSPopen() | | Popen() | | $ ip ad | +---------------------+ +--------------+ +------------+ As a workaround for the issue with file descriptors, some additional methods are available on file objects `stdin`, `stdout` and `stderr`. E.g., one can run fcntl calls:: from fcntl import F_GETFL from pyroute2 import NSPopen from subprocess import PIPE proc = NSPopen('test', ['my_program'], stdout=PIPE) flags = proc.stdout.fcntl(F_GETFL) In that way one can use `fcntl()`, `ioctl()`, `flock()` and `lockf()` calls. Another additional method is `release()`, which can be used to explicitly stop the proxy process and release all the resources. ''' def __init__(self, nsname, *argv, **kwarg): ''' The only differences from the `subprocess.Popen` init are: * `nsname` -- network namespace name * `flags` keyword argument All other arguments are passed directly to `subprocess.Popen`. Flags usage samples. Create a network namespace, if it doesn't exist yet:: import os nsp = NSPopen('nsname', ['command'], flags=os.O_CREAT) Create a network namespace only if it doesn't exist, otherwise fail and raise an exception:: import os nsp = NSPopen('nsname', ['command'], flags=os.O_CREAT | os.O_EXCL) ''' # create a child self.nsname = nsname if 'flags' in kwarg: self.flags = kwarg.pop('flags') else: self.flags = 0 self.channel_out = MpQueue() self.channel_in = MpQueue() self.lock = threading.Lock() self.released = False self.server = MpProcess(target=NSPopenServer, args=(self.nsname, self.flags, self.channel_out, self.channel_in, argv, kwarg)) # start the child and check the status self.server.start() response = self.channel_in.get() if isinstance(response, Exception): self.server.join() raise response else: atexit.register(self.release) def release(self): ''' Explicitly stop the proxy process and release all the resources. The `NSPopen` object can not be used after the `release()` call. ''' with self.lock: if self.released: return self.released = True self.channel_out.put({'name': 'release'}) self.channel_out.close() self.channel_in.close() self.server.join() def __dir__(self): return list(self.api.keys()) + ['release']
class NSPopen(NSPopenBase, ObjNS): ''' A proxy class to run `Popen()` object in some network namespace. Sample to run `ip ad` command in `nsname` network namespace:: nsp = NSPopen('nsname', ['ip', 'ad'], stdout=subprocess.PIPE) print(nsp.communicate()) nsp.wait() nsp.release() The only difference in the `release()` call. It explicitly ends the proxy process and releases all the resources. ''' def __init__(self, nsname, *argv, **kwarg): ''' The only differences from the `subprocess.Popen` init are: * `nsname` -- network namespace name * `flags` keyword argument All other arguments are passed directly to `subprocess.Popen`. Flags usage samples. Create a network namespace, if it doesn't exist yet:: import os nsp = NSPopen('nsname', ['command'], flags=os.O_CREAT) Create a network namespace only if it doesn't exist, otherwise fail and raise an exception:: import os nsp = NSPopen('nsname', ['command'], flags=os.O_CREAT | os.O_EXCL) ''' # create a child self.nsname = nsname if 'flags' in kwarg: self.flags = kwarg.pop('flags') else: self.flags = 0 self.channel_out = MpQueue() self.channel_in = MpQueue() self.lock = threading.Lock() self.released = False self.server = MpProcess(target=NSPopenServer, args=(self.nsname, self.flags, self.channel_out, self.channel_in, argv, kwarg)) # start the child and check the status self.server.start() response = self.channel_in.get() if isinstance(response, Exception): self.server.join() raise response else: atexit.register(self.release) def release(self): ''' Explicitly stop the proxy process and release all the resources. The `NSPopen` object can not be used after the `release()` call. ''' with self.lock: if self.released: return self.released = True self.channel_out.put({'name': 'release'}) self.channel_out.close() self.channel_in.close() self.server.join() def __dir__(self): return list(self.api.keys()) + ['release']