418 lines
14 KiB
Python
418 lines
14 KiB
Python
# -*- coding: utf-8 -*- #
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# Copyright 2017 Google LLC. All Rights Reserved.
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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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#
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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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"""Implements the command for modifying the user's SSH config."""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import unicode_literals
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import io
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import os
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import re
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import stat
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import textwrap
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from googlecloudsdk.api_lib.compute import base_classes
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from googlecloudsdk.api_lib.compute import lister
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from googlecloudsdk.api_lib.compute import path_simplifier
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from googlecloudsdk.api_lib.compute import utils
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from googlecloudsdk.calliope import base
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from googlecloudsdk.calliope import exceptions
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from googlecloudsdk.command_lib.compute import ssh_utils
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from googlecloudsdk.command_lib.util.ssh import ssh
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from googlecloudsdk.core import log
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from googlecloudsdk.core import properties
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from googlecloudsdk.core.util import files
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from googlecloudsdk.core.util import platforms
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# DO NOT CHANGE THE NEXT TWO LINES.
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#
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# Some clients depend on these two delimiters, so changing them will
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# be very problematic for those clients.
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_BEGIN_MARKER = '# Google Compute Engine Section'
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_END_MARKER = '# End of Google Compute Engine Section'
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_BEGIN_RE = re.compile(_BEGIN_MARKER)
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_END_RE = re.compile(_END_MARKER)
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_HEADER = _BEGIN_MARKER + """
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#
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# The following has been auto-generated by "gcloud compute config-ssh"
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# to make accessing your Google Compute Engine virtual machines easier.
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#
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# To remove this blob, run:
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#
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# gcloud compute config-ssh --remove
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#
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# You can also manually remove this blob by deleting everything from
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# here until the comment that contains the string "End of Google Compute
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# Engine Section".
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#
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# You should not hand-edit this section, unless you are deleting it.
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#
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"""
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_SECTION_RE = re.compile(r'(^{begin}\n*?(Host.*?)\n+{end}\n?)'.format(
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begin=_HEADER, end=_END_MARKER),
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flags=re.MULTILINE | re.DOTALL)
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_HOST_RE = re.compile(r'Host (.*?)\n', flags=re.IGNORECASE)
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@base.UniverseCompatible
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class MultipleComputeSectionsError(exceptions.ToolException):
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"""Multiple compute sections are disallowed."""
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def __init__(self, ssh_config_file='the SSH configuration file'):
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super(MultipleComputeSectionsError, self).__init__(
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'Found more than one Google Compute Engine section in [{0}]. '
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'You can either delete [{0}] and let this command recreate it for '
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'you or you can manually delete all sections marked with '
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'[{1}] and [{2}].'.format(ssh_config_file, _BEGIN_MARKER, _END_MARKER))
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def _RemoveComputeSection(existing_content):
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"""Returns the contents of ssh_config_file with compute section removed.
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Args:
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existing_content: str, Current content of ssh config file.
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Raises:
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MultipleComputeSectionsError: If the config file has multiple compute
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sections already.
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Returns:
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A string containing the contents of ssh_config_file with the compute
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section removed.
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"""
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match = _SECTION_RE.search(existing_content)
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if not match:
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return existing_content
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if not _ComputeSectionValid(existing_content):
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raise MultipleComputeSectionsError()
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return existing_content[:match.start(1)] + existing_content[match.end(1):]
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def _ComputeSectionValid(existing_content):
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"""False if compute section invalid, otherwise True."""
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if len(_BEGIN_RE.findall(existing_content)) != 1:
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return False
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if len(_END_RE.findall(existing_content)) != 1:
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return False
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match = _SECTION_RE.search(existing_content)
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if not match:
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return False
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return True
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def _MergeComputeSections(existing_content, compute_section):
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"""Merges a new compute section into an existing compute section.
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Appends new host entries into the compute section. If any of the newly
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appended entries match the host of a previous compute section entry, the
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previous entry is removed. The resulting merged configuration file contents
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are returned. This function has no side effects, and does not directly change
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the contents of the configuration file.
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Args:
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existing_content: str, Current content of ssh config file.
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compute_section: str, New content to be added to the compute section.
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Raises:
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MultipleComputeSectionsError: If the config file has multiple compute
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sections already.
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Returns:
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A string containing the new contents of the ssh configuration file after
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merging the new entries for the compute section.
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"""
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match = _SECTION_RE.search(existing_content)
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if not match:
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# There are no existing Compute Engine sections. If there is
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# at least one instance in the project (signified by
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# compute_section not being None), we append it to the end of
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# the configs. Otherwise, we set content to None which will
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# cause nothing to be written to the SSH config file.
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if compute_section:
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# Ensures that there is a blank line between the existing
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# configs and the Compute section.
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if existing_content[-1] != '\n':
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existing_content += '\n'
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if existing_content[-2:] != '\n\n':
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existing_content += '\n'
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new_content = existing_content + compute_section
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else:
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new_content = existing_content
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elif not _ComputeSectionValid(existing_content):
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# Multiple Compute Engine sections.
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raise MultipleComputeSectionsError()
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elif not compute_section:
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# One Compute Engine section, but no new content to add.
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return existing_content
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else:
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# One Compute Engine section -- append to it.
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new_hosts = _HOST_RE.findall(compute_section)
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existing_hosts = match.group(2).split('\n\n')
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hosts = [host for host in existing_hosts if _HOST_RE.search(host).group(1)
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not in new_hosts]
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hosts.append(_SECTION_RE.search(compute_section).group(2))
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compute_section = '\n\n'.join(hosts)
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new_content = (existing_content[0:match.start(2)] +
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compute_section +
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existing_content[match.end(2):])
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return new_content
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def _CreateAlias(instance_resource):
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"""Returns the alias for the given instance."""
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parts = [
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instance_resource.name,
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path_simplifier.Name(instance_resource.zone),
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properties.VALUES.core.project.Get(required=True),
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]
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return '.'.join(parts)
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def _BuildComputeSection(instances, private_key_file, known_hosts_file):
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"""Returns a string representing the Compute section that should be added."""
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temp_buf = []
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for instance in instances:
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external_ip_address = (
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ssh_utils.GetExternalIPAddress(instance, no_raise=True))
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host_key_alias = 'compute.{0}'.format(instance.id)
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if external_ip_address:
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temp_buf.extend(textwrap.dedent("""\
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Host {alias}
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HostName {external_ip_address}
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IdentityFile {private_key_file}
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UserKnownHostsFile={known_hosts_file}
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HostKeyAlias={host_key_alias}
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IdentitiesOnly=yes
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CheckHostIP=no
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""".format(alias=_CreateAlias(instance),
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external_ip_address=external_ip_address,
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private_key_file=private_key_file,
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known_hosts_file=known_hosts_file,
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host_key_alias=host_key_alias)))
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if temp_buf:
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buf = io.StringIO()
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buf.write(_HEADER)
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for i in temp_buf:
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buf.write(i)
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buf.write(_END_MARKER)
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buf.write('\n')
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return buf.getvalue()
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else:
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return ''
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@base.UniverseCompatible
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@base.ReleaseTracks(base.ReleaseTrack.GA, base.ReleaseTrack.BETA,
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base.ReleaseTrack.ALPHA)
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class ConfigSSH(base.Command):
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"""Populate SSH config files with Host entries from each instance.
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*{command}* makes SSHing to virtual machine instances easier
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by adding an alias for each instance to the user SSH configuration
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(`~/.ssh/config`) file.
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In most cases, it is sufficient to run:
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$ {command}
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Each instance will be given an alias of the form
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`NAME.ZONE.PROJECT`. For example, if `example-instance` resides in
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`us-central1-a`, you can SSH to it by running:
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$ ssh example-instance.us-central1-a.MY-PROJECT
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On some platforms, the host alias can be tab-completed, making
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the long alias less daunting to type.
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The aliases created interface with SSH-based programs like
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*scp(1)*, so it is possible to use the aliases elsewhere:
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$ scp ~/MY-FILE example-instance.us-central1-a.MY-PROJECT:~
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Whenever instances are added, removed, or their external IP addresses are
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changed, the remove command must be run to clear the existing configuration
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and then the command can set executed to set the configuration to the current
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state.
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This command ensures that the user's public SSH key is present
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in the project's metadata. If the user does not have a public
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SSH key, one is generated using *ssh-keygen(1)* (if the `--quiet`
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flag is given, the generated key will have an empty passphrase).
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## EXAMPLES
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To populate SSH config file with Host entries from each running instance, run:
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$ {command}
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To remove the change to the SSH config file by this command, run:
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$ {command} --remove
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"""
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category = base.TOOLS_CATEGORY
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@staticmethod
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def Args(parser):
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"""Set up arguments for this command.
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Args:
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parser: An argparse.ArgumentParser.
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"""
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ssh_utils.BaseSSHHelper.Args(parser)
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parser.add_argument(
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'--ssh-config-file',
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help="""\
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Specifies an alternative per-user SSH configuration file. By
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default, this is ``{0}''.
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""".format(ssh.PER_USER_SSH_CONFIG_FILE))
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parser.add_argument(
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'--dry-run',
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action='store_true',
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help=('If provided, the proposed changes to the SSH config file are '
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'printed to standard output and no actual changes are made.'))
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parser.add_argument(
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'--remove',
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action='store_true',
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help=('If provided, any changes made to the SSH config file by this '
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'tool are reverted.'))
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def GetRunningInstances(self, client):
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"""Returns a generator of all running instances in the project."""
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errors = []
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instances = lister.GetZonalResources(
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service=client.apitools_client.instances,
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project=properties.VALUES.core.project.GetOrFail(),
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requested_zones=None,
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filter_expr='status eq RUNNING',
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http=client.apitools_client.http,
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batch_url=client.batch_url,
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errors=errors)
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if errors:
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utils.RaiseToolException(
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errors, error_message='Could not fetch all instances:')
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return instances
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def Run(self, args):
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"""See ssh_utils.BaseSSHCommand.Run."""
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holder = base_classes.ComputeApiHolder(self.ReleaseTrack())
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client = holder.client
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ssh_helper = ssh_utils.BaseSSHHelper()
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ssh_helper.Run(args)
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ssh_helper.keys.EnsureKeysExist(args.force_key_file_overwrite,
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allow_passphrase=True)
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ssh_config_file = files.ExpandHomeDir(
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args.ssh_config_file or ssh.PER_USER_SSH_CONFIG_FILE)
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instances = None
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try:
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existing_content = files.ReadFileContents(ssh_config_file)
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except files.Error as e:
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existing_content = ''
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log.debug('SSH Config File [{0}] could not be opened: {1}'
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.format(ssh_config_file, e))
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if args.remove:
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compute_section = ''
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try:
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new_content = _RemoveComputeSection(existing_content)
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except MultipleComputeSectionsError:
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raise MultipleComputeSectionsError(ssh_config_file)
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else:
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ssh_helper.EnsureSSHKeyIsInProject(
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client, ssh.GetDefaultSshUsername(warn_on_account_user=True), None)
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instances = list(self.GetRunningInstances(client))
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if instances:
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compute_section = _BuildComputeSection(
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instances, ssh_helper.keys.key_file, ssh.KnownHosts.DEFAULT_PATH)
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else:
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compute_section = ''
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if existing_content and not args.remove:
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try:
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new_content = _MergeComputeSections(existing_content, compute_section)
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except MultipleComputeSectionsError:
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raise MultipleComputeSectionsError(ssh_config_file)
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elif not existing_content:
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new_content = compute_section
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if args.dry_run:
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log.out.write(new_content or '')
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return
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if new_content != existing_content:
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if (os.path.exists(ssh_config_file) and
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platforms.OperatingSystem.Current() is not
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platforms.OperatingSystem.WINDOWS):
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ssh_config_perms = os.stat(ssh_config_file).st_mode
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# From `man 5 ssh_config`:
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# this file must have strict permissions: read/write for the user,
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# and not accessible by others.
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# We check that here:
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if not (
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ssh_config_perms & stat.S_IRWXU == stat.S_IWUSR | stat.S_IRUSR and
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ssh_config_perms & stat.S_IWGRP == 0 and
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ssh_config_perms & stat.S_IWOTH == 0):
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log.warning(
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'Invalid permissions on [{0}]. Please change to match ssh '
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'requirements (see man 5 ssh).')
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# TODO(b/36050483): This write will not work very well if there is
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# a lot of write contention for the SSH config file. We should
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# add a function to do a better job at "atomic file writes".
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files.WriteFileContents(ssh_config_file, new_content, private=True)
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if compute_section:
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log.out.write(textwrap.dedent("""\
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You should now be able to use ssh/scp with your instances.
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For example, try running:
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$ ssh {alias}
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""".format(alias=_CreateAlias(instances[0]))))
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elif compute_section == '' and instances: # pylint: disable=g-explicit-bool-comparison
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log.warning(
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'No host aliases were added to your SSH configs because instances'
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' have no public IP.')
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elif not instances and not args.remove:
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log.warning(
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'No host aliases were added to your SSH configs because you do not '
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'have any running instances. Try running this command again after '
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'running some instances.')
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