123 lines
4.0 KiB
Python
123 lines
4.0 KiB
Python
# python3
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# Copyright 2019 Google LLC
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Tunnel handles setting up connections to remote machines.
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Tunnel dispatcher is a wrapper around the connection from a local UNIX socket
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and a remote UNIX socket via SSH with port forwarding. This is done to
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initialize the pythonic dockerpy client to run containers on the remote host by
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connecting to /var/run/docker.sock (where Docker is listening). Tunnel
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dispatcher sets up the local UNIX socket and calls the `ssh` command as a
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subprocess, and holds a reference to that subprocess. It manages clean-up on
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exit as best it can by killing the ssh subprocess and deleting the local UNIX
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socket,stored in /tmp for easy cleanup in most systems if this fails.
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Typical usage example:
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t = Tunnel(name, **kwargs)
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t.connect()
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client = t.get_docker_client() #
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client.containers.run("ubuntu", "echo hello world")
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"""
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import os
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import tempfile
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import time
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import docker
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import pexpect
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SSH_TUNNEL_COMMAND = """ssh
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-o GlobalKnownHostsFile=/dev/null
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-o UserKnownHostsFile=/dev/null
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-o StrictHostKeyChecking=no
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-o IdentitiesOnly=yes
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-nNT -L {filename}:/var/run/docker.sock
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-i {key_path}
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{username}@{hostname}"""
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class Tunnel(object):
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"""The tunnel object represents the tunnel via ssh.
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This connects a local unix domain socket with a remote socket.
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Attributes:
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_filename: a temporary name of the UNIX socket prefixed by the name
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argument.
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_hostname: the IP or resolvable hostname of the remote host.
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_username: the username of the ssh_key used to run ssh.
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_key_path: path to a valid key.
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_key_password: optional password to the ssh key in _key_path
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_process: holds reference to the ssh subprocess created.
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Returns:
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The new minimum port.
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Raises:
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ConnectionError: If no available port is found.
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"""
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def __init__(self,
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name: str,
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hostname: str,
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username: str,
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key_path: str,
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key_password: str = "",
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**kwargs):
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self._filename = tempfile.NamedTemporaryFile(prefix=name).name
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self._hostname = hostname
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self._username = username
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self._key_path = key_path
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self._key_password = key_password
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self._kwargs = kwargs
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self._process = None
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def connect(self):
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"""Connects the SSH tunnel and stores the subprocess reference in _process."""
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cmd = SSH_TUNNEL_COMMAND.format(
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filename=self._filename,
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key_path=self._key_path,
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username=self._username,
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hostname=self._hostname)
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self._process = pexpect.spawn(cmd, timeout=10)
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# If given a password, assume we'll be asked for it.
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if self._key_password:
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self._process.expect(["Enter passphrase for key .*: "])
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self._process.sendline(self._key_password)
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while True:
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# Wait for the tunnel to appear.
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if self._process.exitstatus is not None:
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raise ConnectionError("Error in setting up ssh tunnel")
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if os.path.exists(self._filename):
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return
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time.sleep(0.1)
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def path(self):
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"""Return the socket file."""
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return self._filename
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def get_docker_client(self):
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"""Returns a docker client for this Tunnel."""
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return docker.DockerClient(base_url="unix:/" + self._filename)
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def __del__(self):
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"""Closes the ssh connection process and deletes the socket file."""
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if self._process:
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self._process.close()
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if os.path.exists(self._filename):
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os.remove(self._filename)
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