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authentik/authentik/outposts/docker_ssh.py

99 lines
3.4 KiB
Python

"""Docker SSH helper"""
import os
from pathlib import Path
from tempfile import gettempdir
from docker.errors import DockerException
from authentik.crypto.models import CertificateKeyPair
HEADER = "### Managed by authentik"
FOOTER = "### End Managed by authentik"
def opener(path, flags):
"""File opener to create files as 700 perms"""
return os.open(path, flags, 0o700)
class SSHManagedExternallyException(DockerException):
"""Raised when the ssh config file is managed externally."""
class DockerInlineSSH:
"""Create paramiko ssh config from CertificateKeyPair"""
host: str
keypair: CertificateKeyPair
key_path: str
config_path: Path
header: str
def __init__(self, host: str, keypair: CertificateKeyPair) -> None:
self.host = host
self.keypair = keypair
self.config_path = Path("~/.ssh/config").expanduser()
if self.config_path.exists() and HEADER not in self.config_path.read_text(encoding="utf-8"):
# SSH Config file already exists and there's no header from us, meaning that it's
# been externally mapped into the container for more complex configs
raise SSHManagedExternallyException(
"SSH Config exists and does not contain authentik header"
)
if not self.keypair:
raise DockerException("keypair must be set for SSH connections")
self.header = f"{HEADER} - {self.host}\n"
def write_config(self, key_path: str) -> bool:
"""Update the local user's ssh config file"""
with open(self.config_path, "a+", encoding="utf-8") as ssh_config:
if self.header in ssh_config.readlines():
return False
ssh_config.writelines(
[
self.header,
f"Host {self.host}\n",
f" IdentityFile {key_path}\n",
" StrictHostKeyChecking No\n",
" UserKnownHostsFile /dev/null\n",
f"{FOOTER}\n",
"\n",
]
)
return True
def write_key(self):
"""Write keypair's private key to a temporary file"""
path = Path(gettempdir(), f"{self.keypair.pk}_private.pem")
with open(path, "w", encoding="utf8", opener=opener) as _file:
_file.write(self.keypair.key_data)
return str(path)
def write(self):
"""Write keyfile and update ssh config"""
self.key_path = self.write_key()
was_written = self.write_config(self.key_path)
if not was_written:
self.cleanup()
def cleanup(self):
"""Cleanup when we're done"""
try:
os.unlink(self.key_path)
with open(self.config_path, "r", encoding="utf-8") as ssh_config:
start = 0
end = 0
lines = ssh_config.readlines()
for idx, line in enumerate(lines):
if line == self.header:
start = idx
if start != 0 and line == f"{FOOTER}\n":
end = idx
with open(self.config_path, "w+", encoding="utf-8") as ssh_config:
lines = lines[:start] + lines[end + 2 :]
ssh_config.writelines(lines)
except OSError:
# If we fail deleting a file it doesn't matter that much
# since we're just in a container
pass