|
| 1 | +#!/usr/bin/env python |
| 2 | + |
| 3 | +# Copyright 2018 Google Inc. All Rights Reserved. |
| 4 | +# |
| 5 | +# Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | +# you may not use this file except in compliance with the License. |
| 7 | +# You may obtain a copy of the License at |
| 8 | +# |
| 9 | +# http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | +# |
| 11 | +# Unless required by applicable law or agreed to in writing, software |
| 12 | +# distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | +# See the License for the specific language governing permissions and |
| 15 | +# limitations under the License. |
| 16 | + |
| 17 | +"""Example of using the OS Login API to apply public SSH keys for a service |
| 18 | +account, and use that service account to execute commands on a remote |
| 19 | +instance over SSH. This example uses zonal DNS names to address instances |
| 20 | +on the same internal VPC network. |
| 21 | +""" |
| 22 | + |
| 23 | +# [START imports_and_variables] |
| 24 | +import time |
| 25 | +import subprocess |
| 26 | +import uuid |
| 27 | +import logging |
| 28 | +import requests |
| 29 | +import argparse |
| 30 | +import googleapiclient.discovery |
| 31 | + |
| 32 | +# Global variables |
| 33 | +SERVICE_ACCOUNT_METADATA_URL = ( |
| 34 | + 'http://metadata.google.internal/computeMetadata/v1/instance/' |
| 35 | + 'service-accounts/default/email') |
| 36 | +HEADERS = {'Metadata-Flavor': 'Google'} |
| 37 | + |
| 38 | +# [END imports_and_variables] |
| 39 | + |
| 40 | + |
| 41 | +# [START run_command_local] |
| 42 | +def execute(cmd, cwd=None, capture_output=False, env=None, raise_errors=True): |
| 43 | + """Execute an external command (wrapper for Python subprocess).""" |
| 44 | + logging.info('Executing command: {cmd}'.format(cmd=str(cmd))) |
| 45 | + stdout = subprocess.PIPE if capture_output else None |
| 46 | + process = subprocess.Popen(cmd, cwd=cwd, env=env, stdout=stdout) |
| 47 | + output = process.communicate()[0] |
| 48 | + returncode = process.returncode |
| 49 | + if returncode: |
| 50 | + # Error |
| 51 | + if raise_errors: |
| 52 | + raise subprocess.CalledProcessError(returncode, cmd) |
| 53 | + else: |
| 54 | + logging.info('Command returned error status %s', returncode) |
| 55 | + if output: |
| 56 | + logging.info(output) |
| 57 | + return returncode, output |
| 58 | +# [END run_command_local] |
| 59 | + |
| 60 | + |
| 61 | +# [START create_key] |
| 62 | +def create_ssh_key(oslogin, account, private_key_file=None, expire_time=300): |
| 63 | + """Generate an SSH key pair and apply it to the specified account.""" |
| 64 | + private_key_file = private_key_file or '/tmp/key-' + str(uuid.uuid4()) |
| 65 | + execute(['ssh-keygen', '-t', 'rsa', '-N', '', '-f', private_key_file]) |
| 66 | + |
| 67 | + with open(private_key_file + '.pub', 'r') as original: |
| 68 | + public_key = original.read().strip() |
| 69 | + |
| 70 | + # Expiration time is in microseconds. |
| 71 | + expiration = int((time.time() + expire_time) * 1000000) |
| 72 | + |
| 73 | + body = { |
| 74 | + 'key': public_key, |
| 75 | + 'expirationTimeUsec': expiration, |
| 76 | + } |
| 77 | + oslogin.users().importSshPublicKey(parent=account, body=body).execute() |
| 78 | + return private_key_file |
| 79 | +# [END create_key] |
| 80 | + |
| 81 | + |
| 82 | +# [START run_command_remote] |
| 83 | +def run_ssh(cmd, private_key_file, username, hostname): |
| 84 | + """Run a command on a remote system.""" |
| 85 | + ssh_command = [ |
| 86 | + 'ssh', '-i', private_key_file, '-o', 'StrictHostKeyChecking=no', |
| 87 | + '{username}@{hostname}'.format(username=username, hostname=hostname), |
| 88 | + cmd, |
| 89 | + ] |
| 90 | + ssh = subprocess.Popen( |
| 91 | + ssh_command, shell=False, stdout=subprocess.PIPE, |
| 92 | + stderr=subprocess.PIPE) |
| 93 | + result = ssh.stdout.readlines() |
| 94 | + return result if result else ssh.stderr.readlines() |
| 95 | + |
| 96 | +# [END run_command_remote] |
| 97 | + |
| 98 | + |
| 99 | +# [START main] |
| 100 | +def main(cmd, project, instance=None, zone=None, |
| 101 | + oslogin=None, account=None, hostname=None): |
| 102 | + """Run a command on a remote system.""" |
| 103 | + |
| 104 | + # Create the OS Login API object. |
| 105 | + oslogin = oslogin or googleapiclient.discovery.build('oslogin', 'v1') |
| 106 | + |
| 107 | + # Identify the service account ID if it is not already provided. |
| 108 | + account = account or requests.get( |
| 109 | + SERVICE_ACCOUNT_METADATA_URL, headers=HEADERS).text |
| 110 | + account = 'users/' + account |
| 111 | + |
| 112 | + # Create a new SSH key pair and associate it with the service account. |
| 113 | + private_key_file = create_ssh_key(oslogin, account) |
| 114 | + |
| 115 | + # Using the OS Login API, get the POSIX user name from the login profile |
| 116 | + # for the service account. |
| 117 | + profile = oslogin.users().getLoginProfile(name=account).execute() |
| 118 | + username = profile.get('posixAccounts')[0].get('username') |
| 119 | + |
| 120 | + # Create the hostname of the target instance using the instance name, |
| 121 | + # the zone where the instance is located, and the project that owns the |
| 122 | + # instance. |
| 123 | + hostname = hostname or '{instance}.{zone}.c.{project}.internal'.format( |
| 124 | + instance=instance, zone=zone, project=project) |
| 125 | + |
| 126 | + # Run a command on the remote instance over SSH. |
| 127 | + result = run_ssh(cmd, private_key_file, username, hostname) |
| 128 | + |
| 129 | + # Print the command line output from the remote instance. |
| 130 | + # Use .rstrip() rather than end='' for Python 2 compatability. |
| 131 | + for line in result: |
| 132 | + print(line.decode('utf-8').rstrip('\n\r')) |
| 133 | + |
| 134 | + # Shred the private key and delete the pair. |
| 135 | + execute(['shred', private_key_file]) |
| 136 | + execute(['rm', private_key_file]) |
| 137 | + execute(['rm', private_key_file + '.pub']) |
| 138 | + |
| 139 | + |
| 140 | +if __name__ == '__main__': |
| 141 | + |
| 142 | + parser = argparse.ArgumentParser( |
| 143 | + description=__doc__, |
| 144 | + formatter_class=argparse.RawDescriptionHelpFormatter) |
| 145 | + parser.add_argument( |
| 146 | + '--cmd', default='uname -a', |
| 147 | + help='The command to run on the remote instance.') |
| 148 | + parser.add_argument( |
| 149 | + '--project', |
| 150 | + help='Your Google Cloud project ID.') |
| 151 | + parser.add_argument( |
| 152 | + '--zone', |
| 153 | + help='The zone where the target instance is locted.') |
| 154 | + parser.add_argument( |
| 155 | + '--instance', |
| 156 | + help='The target instance for the ssh command.') |
| 157 | + parser.add_argument( |
| 158 | + '--account', |
| 159 | + help='The service account email.') |
| 160 | + parser.add_argument( |
| 161 | + '--hostname', |
| 162 | + help='The external IP address or hostname for the target instance.') |
| 163 | + args = parser.parse_args() |
| 164 | + |
| 165 | + main(args.cmd, args.project, instance=args.instance, zone=args.zone, |
| 166 | + account=args.account, hostname=args.hostname) |
| 167 | + |
| 168 | +# [END main] |
0 commit comments