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"""High level functions for working with SSH."""
from __future__ import annotations
import dataclasses
import json
import os
import random
import re
import subprocess
import shlex
import typing as t
from .encoding import (
to_bytes,
to_text,
)
from .util import (
ApplicationError,
common_environment,
display,
exclude_none_values,
sanitize_host_name,
)
from .config import (
EnvironmentConfig,
)
@dataclasses.dataclass
class SshConnectionDetail:
"""Information needed to establish an SSH connection to a host."""
name: str
host: str
port: t.Optional[int]
user: str
identity_file: str
python_interpreter: t.Optional[str] = None
shell_type: t.Optional[str] = None
def __post_init__(self):
self.name = sanitize_host_name(self.name)
class SshProcess:
"""Wrapper around an SSH process."""
def __init__(self, process: t.Optional[subprocess.Popen]) -> None:
self._process = process
self.pending_forwards: t.Optional[list[tuple[str, int]]] = None
self.forwards: dict[tuple[str, int], int] = {}
def terminate(self) -> None:
"""Terminate the SSH process."""
if not self._process:
return # explain mode
# noinspection PyBroadException
try:
self._process.terminate()
except Exception: # pylint: disable=broad-except
pass
def wait(self) -> None:
"""Wait for the SSH process to terminate."""
if not self._process:
return # explain mode
self._process.wait()
def collect_port_forwards(self) -> dict[tuple[str, int], int]:
"""Collect port assignments for dynamic SSH port forwards."""
errors: list[str] = []
display.info('Collecting %d SSH port forward(s).' % len(self.pending_forwards), verbosity=2)
while self.pending_forwards:
if self._process:
line_bytes = self._process.stderr.readline()
if not line_bytes:
if errors:
details = ':\n%s' % '\n'.join(errors)
else:
details = '.'
raise ApplicationError('SSH port forwarding failed%s' % details)
line = to_text(line_bytes).strip()
match = re.search(r'^Allocated port (?P<src_port>[0-9]+) for remote forward to (?P<dst_host>[^:]+):(?P<dst_port>[0-9]+)$', line)
if not match:
if re.search(r'^Warning: Permanently added .* to the list of known hosts\.$', line):
continue
display.warning('Unexpected SSH port forwarding output: %s' % line, verbosity=2)
errors.append(line)
continue
src_port = int(match.group('src_port'))
dst_host = str(match.group('dst_host'))
dst_port = int(match.group('dst_port'))
dst = (dst_host, dst_port)
else:
# explain mode
dst = self.pending_forwards[0]
src_port = random.randint(40000, 50000)
self.pending_forwards.remove(dst)
self.forwards[dst] = src_port
display.info('Collected %d SSH port forward(s):\n%s' % (
len(self.forwards), '\n'.join('%s -> %s:%s' % (src_port, dst[0], dst[1]) for dst, src_port in sorted(self.forwards.items()))), verbosity=2)
return self.forwards
def create_ssh_command(
ssh: SshConnectionDetail,
options: t.Optional[dict[str, t.Union[str, int]]] = None,
cli_args: list[str] = None,
command: t.Optional[str] = None,
) -> list[str]:
"""Create an SSH command using the specified options."""
cmd = [
'ssh',
'-n', # prevent reading from stdin
'-i', ssh.identity_file, # file from which the identity for public key authentication is read
]
if not command:
cmd.append('-N') # do not execute a remote command
if ssh.port:
cmd.extend(['-p', str(ssh.port)]) # port to connect to on the remote host
if ssh.user:
cmd.extend(['-l', ssh.user]) # user to log in as on the remote machine
ssh_options = dict(
BatchMode='yes',
ExitOnForwardFailure='yes',
LogLevel='ERROR',
ServerAliveCountMax=4,
ServerAliveInterval=15,
StrictHostKeyChecking='no',
UserKnownHostsFile='/dev/null',
)
ssh_options.update(options or {})
for key, value in sorted(ssh_options.items()):
cmd.extend(['-o', '='.join([key, str(value)])])
cmd.extend(cli_args or [])
cmd.append(ssh.host)
if command:
cmd.append(command)
return cmd
def run_ssh_command(
args: EnvironmentConfig,
ssh: SshConnectionDetail,
options: t.Optional[dict[str, t.Union[str, int]]] = None,
cli_args: list[str] = None,
command: t.Optional[str] = None,
) -> SshProcess:
"""Run the specified SSH command, returning the created SshProcess instance created."""
cmd = create_ssh_command(ssh, options, cli_args, command)
env = common_environment()
cmd_show = shlex.join(cmd)
display.info('Run background command: %s' % cmd_show, verbosity=1, truncate=True)
cmd_bytes = [to_bytes(arg) for arg in cmd]
env_bytes = dict((to_bytes(k), to_bytes(v)) for k, v in env.items())
if args.explain:
process = SshProcess(None)
else:
process = SshProcess(subprocess.Popen(cmd_bytes, env=env_bytes, bufsize=-1, # pylint: disable=consider-using-with
stdin=subprocess.DEVNULL, stdout=subprocess.PIPE, stderr=subprocess.PIPE))
return process
def create_ssh_port_forwards(
args: EnvironmentConfig,
ssh: SshConnectionDetail,
forwards: list[tuple[str, int]],
) -> SshProcess:
"""
Create SSH port forwards using the provided list of tuples (target_host, target_port).
Port bindings will be automatically assigned by SSH and must be collected with a subsequent call to collect_port_forwards.
"""
options: dict[str, t.Union[str, int]] = dict(
LogLevel='INFO', # info level required to get messages on stderr indicating the ports assigned to each forward
)
cli_args = []
for forward_host, forward_port in forwards:
cli_args.extend(['-R', ':'.join([str(0), forward_host, str(forward_port)])])
process = run_ssh_command(args, ssh, options, cli_args)
process.pending_forwards = forwards
return process
def create_ssh_port_redirects(
args: EnvironmentConfig,
ssh: SshConnectionDetail,
redirects: list[tuple[int, str, int]],
) -> SshProcess:
"""Create SSH port redirections using the provided list of tuples (bind_port, target_host, target_port)."""
options: dict[str, t.Union[str, int]] = {}
cli_args = []
for bind_port, target_host, target_port in redirects:
cli_args.extend(['-R', ':'.join([str(bind_port), target_host, str(target_port)])])
process = run_ssh_command(args, ssh, options, cli_args)
return process
def generate_ssh_inventory(ssh_connections: list[SshConnectionDetail]) -> str:
"""Return an inventory file in JSON format, created from the provided SSH connection details."""
inventory = dict(
all=dict(
hosts=dict((ssh.name, exclude_none_values(dict(
ansible_host=ssh.host,
ansible_port=ssh.port,
ansible_user=ssh.user,
ansible_ssh_private_key_file=os.path.abspath(ssh.identity_file),
ansible_connection='ssh',
ansible_pipelining='yes',
ansible_python_interpreter=ssh.python_interpreter,
ansible_shell_type=ssh.shell_type,
ansible_ssh_extra_args='-o UserKnownHostsFile=/dev/null', # avoid changing the test environment
ansible_ssh_host_key_checking='no',
))) for ssh in ssh_connections),
),
)
inventory_text = json.dumps(inventory, indent=4, sort_keys=True)
display.info('>>> SSH Inventory\n%s' % inventory_text, verbosity=3)
return inventory_text
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