ceph-deploy 中使用remoto

在ceph-deploy 中使用remoto 这个第三方库来访问远程host.这个库的源码的路径为https://github.com/alfredodeza/remoto例如在E:\ceph-deploy-master\ceph-deploy-master\ceph_deploy\hosts\common.py 中def ceph_version(conn):    """    Log the remote ceph-version by calling `ceph --version`    """    return remoto.process.run(conn, ['ceph', '--version'])通过remoto.process.run在远程host 上运行ceph --version其源码分析如下：路径为https://github.com/alfredodeza/remoto/blob/222014a3da8bb77cb462bace3a6c0e7200e5ea08/remoto/process.pydef run(conn, command, exit=False, timeout=None, **kw):    """    A real-time-logging implementation of a remote subprocess.Popen call where    a command is just executed on the remote end and no other handling is done.    :param conn: A connection oject    :param command: The command to pass in to the remote subprocess.Popen    :param exit: If this call should close the connection at the end    :param timeout: How many seconds to wait after no remote data is received                    (defaults to wait for ever)    """    stop_on_error = kw.pop('stop_on_error', True)    if not kw.get('env'):        # get the remote environment's env so we can explicitly add        # the path without wiping out everything        kw = extend_path(conn, kw)    timeout = timeout or conn.global_timeout    conn.logger.info('Running command: %s' % ' '.join(admin_command(conn.sudo, command)))    result = conn.execute(_remote_run, cmd=command, **kw)可见这里调用_remote_run，def _remote_run(channel, cmd, **kw):    import subprocess    import sys    from select import select    stop_on_nonzero = kw.pop('stop_on_nonzero', True)    process = subprocess.Popen(        cmd,        stdout=subprocess.PIPE,        stderr=subprocess.PIPE,        close_fds=True,        **kw    )原来最后还是调用subprocess 这个第三方库来运行命令，可见remoto 只是subprocess的一个包装第二个ceph-deploy的例子def mon_create(distro, args, monitor_keyring):    hostname = distro.conn.remote_module.shortname()这里的remote_module定义如下：路径为https://github.com/alfredodeza/remoto/blob/1e4fbd0f1af5e68ef0d824dd8b93139c3b86aa05/remoto/connection.pyclass Connection(object):    def __init__(self, hostname, logger=None, sudo=False, threads=1, eager=True,                 detect_sudo=False, interpreter=None):        self.sudo = sudo        self.hostname = hostname        self.logger = logger or FakeRemoteLogger()        self.remote_module = None        self.channel = None        self.global_timeout = None  # wait for ever        self.interpreter = interpreter or 'python%s' % sys.version_info[0]    def _make_gateway(self, hostname):        gateway = execnet.makegateway(            self._make_connection_string(hostname)        )    def import_module(self, module):        self.remote_module = ModuleExecute(self.gateway, module, self.logger)        return self.remote_moduleModuleExecute 是一个类，定义如下：class ModuleExecute(object):    def __init__(self, gateway, module, logger=None):        self.channel = gateway.remote_exec(module)        self.module = module        self.logger = logger所以ceph-depoly中的remote_module.shortname()其实调用的gateway中的shortname()。而gateway的赋值如下：    def _make_gateway(self, hostname):        gateway = execnet.makegateway(            self._make_connection_string(hostname)        )可见是通过execnet 这个第三方库完成的。这里就是调用python解释器去执行_make_connection_string产生的命令execnet的介绍为http://codespeak.net/execnet/execnet provides a share-nothing model with channel-send/receive communication for distributing execution across many Python interpreters across version, platform and network barriers. It has a minimal and fast API targetting the following uses:distribute tasks to (many) local or remote CPUswrite and deploy hybrid multi-process applicationswrite scripts to administer multiple environments