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# python3
# Copyright 2019 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Tunnel handles setting up connections to remote machines."""
import os
import tempfile
import time
import docker
import pexpect
SSH_TUNNEL_COMMAND = """ssh
-o GlobalKnownHostsFile=/dev/null
-o UserKnownHostsFile=/dev/null
-o StrictHostKeyChecking=no
-nNT -L {filename}:/var/run/docker.sock
-i {key_path}
{username}@{hostname}"""
class Tunnel:
"""The tunnel object represents the tunnel via ssh.
This connects a local unix domain socket with a remote socket.
"""
def __init__(self, name, hostname: str, username: str, key_path: str,
**kwargs):
self._filename = tempfile.NamedTemporaryFile(prefix=name).name
self._hostname = hostname
self._username = username
self._key_path = key_path
self._kwargs = kwargs
self._process = None
def connect(self):
"""Connects the SSH tunnel."""
cmd = SSH_TUNNEL_COMMAND.format(
filename=self._filename,
key_path=self._key_path,
username=self._username,
hostname=self._hostname)
self._process = pexpect.spawn(cmd, timeout=10)
# If given a password, assume we'll be asked for it.
if "key_password" in self._kwargs:
self._process.expect(["Enter passphrase for key .*: "])
self._process.sendline(self._kwargs["key_password"])
while True:
# Wait for the tunnel to appear.
if self._process.exitstatus is not None:
raise ConnectionError("Error in setting up ssh tunnel")
if os.path.exists(self._filename):
return
time.sleep(0.1)
def path(self):
"""Return the socket file."""
return self._filename
def get_docker_client(self):
"""Returns a docker client for this Tunne0l."""
return docker.DockerClient(base_url="unix:/" + self._filename)
def __del__(self):
"""Closes the ssh connection process and deletes the socket file."""
if self._process:
self._process.close()
if os.path.exists(self._filename):
os.remove(self._filename)
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