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network: move code out of __init__file
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* Some code in the __init__ file was creating a circular dependency
  issue.
* Move this code into its own modules, this may have efficiecncy
  benefits for other network modules when the code in __init__
  is not required.
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@oliver-sanders
oliver-sanders committed Jun 21, 2024
1 parent 6ab1ede commit c908539
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285 changes: 12 additions & 273 deletions cylc/flow/network/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -13,279 +13,18 @@
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""Package for network interfaces to Cylc scheduler objects."""

import asyncio
import getpass
import json
from typing import Optional, Tuple
"""Cylc networking code.
import zmq
import zmq.asyncio
import zmq.auth
Contains:
* Server code (hosted by the scheduler process).
* Client implementations (used to communicate with the scheduler).
* Workflow scanning logic.
* Schema and interface definitions.
"""

from cylc.flow import LOG
from cylc.flow.exceptions import (
ClientError,
CylcError,
CylcVersionError,
ServiceFileError,
WorkflowStopped
)
from cylc.flow.hostuserutil import get_fqdn_by_host
from cylc.flow.workflow_files import (
ContactFileFields,
KeyType,
KeyOwner,
KeyInfo,
load_contact_file,
get_workflow_srv_dir
)

API = 5 # cylc API version
MSG_TIMEOUT = "TIMEOUT"


def encode_(message):
"""Convert the structure holding a message field from JSON to a string."""
try:
return json.dumps(message)
except TypeError as exc:
return json.dumps({'errors': [{'message': str(exc)}]})


def decode_(message):
"""Convert an encoded message string to JSON with an added 'user' field."""
msg = json.loads(message)
msg['user'] = getpass.getuser() # assume this is the user
return msg


def get_location(workflow: str) -> Tuple[str, int, int]:
"""Extract host and port from a workflow's contact file.
NB: if it fails to load the workflow contact file, it will exit.
Args:
workflow: workflow ID
Returns:
Tuple (host name, port number, publish port number)
Raises:
WorkflowStopped: if the workflow is not running.
CylcVersionError: if target is a Cylc 7 (or earlier) workflow.
"""
try:
contact = load_contact_file(workflow)
except (IOError, ValueError, ServiceFileError):
# Contact file does not exist or corrupted, workflow should be dead
raise WorkflowStopped(workflow)

host = contact[ContactFileFields.HOST]
host = get_fqdn_by_host(host)
port = int(contact[ContactFileFields.PORT])
if ContactFileFields.PUBLISH_PORT in contact:
pub_port = int(contact[ContactFileFields.PUBLISH_PORT])
else:
version = contact.get('CYLC_VERSION', None)
raise CylcVersionError(version=version)
return host, port, pub_port


class ZMQSocketBase:
"""Initiate the ZMQ socket bind for specified pattern.
NOTE: Security to be provided via zmq.auth (see PR #3359).
Args:
pattern (enum): ZeroMQ message pattern (zmq.PATTERN).
context (object, optional): instantiated ZeroMQ context, defaults
to zmq.asyncio.Context().
This class is designed to be inherited by REP Server (REQ/REP)
and by PUB Publisher (PUB/SUB), as the start-up logic is similar.
To tailor this class overwrite it's method on inheritance.
"""

def __init__(
self,
pattern,
workflow: str,
bind: bool = False,
context: Optional[zmq.Context] = None,
):
self.bind = bind
if context is None:
self.context: zmq.Context = zmq.asyncio.Context()
else:
self.context = context
self.pattern = pattern
self.workflow = workflow
self.host: Optional[str] = None
self.port: Optional[int] = None
self.socket: Optional[zmq.Socket] = None
self.loop: Optional[asyncio.AbstractEventLoop] = None
self.stopping = False

def start(self, *args, **kwargs):
"""Create the async loop, and bind socket."""
# set asyncio loop
try:
self.loop = asyncio.get_running_loop()
except RuntimeError:
self.loop = asyncio.new_event_loop()
asyncio.set_event_loop(self.loop)

if self.bind:
self._socket_bind(*args, **kwargs)
else:
self._socket_connect(*args, **kwargs)

# initiate bespoke items
self._bespoke_start()

# Keeping srv_prv_key_loc as optional arg so as to not break interface
def _socket_bind(self, min_port, max_port, srv_prv_key_loc=None):
"""Bind socket.
Will use a port range provided to select random ports.
"""
if srv_prv_key_loc is None:
# Create new KeyInfo object for the server private key
workflow_srv_dir = get_workflow_srv_dir(self.workflow)
srv_prv_key_info = KeyInfo(
KeyType.PRIVATE,
KeyOwner.SERVER,
workflow_srv_dir=workflow_srv_dir)
else:
srv_prv_key_info = KeyInfo(
KeyType.PRIVATE,
KeyOwner.SERVER,
full_key_path=srv_prv_key_loc)

# create socket
self.socket = self.context.socket(self.pattern)
self._socket_options()

try:
server_public_key, server_private_key = zmq.auth.load_certificate(
srv_prv_key_info.full_key_path)
except ValueError:
raise ServiceFileError(
f"Failed to find server's public "
f"key in "
f"{srv_prv_key_info.full_key_path}."
)
except OSError:
raise ServiceFileError(
f"IO error opening server's private "
f"key from "
f"{srv_prv_key_info.full_key_path}."
)
if server_private_key is None: # this can't be caught by exception
raise ServiceFileError(
f"Failed to find server's private "
f"key in "
f"{srv_prv_key_info.full_key_path}."
)
self.socket.curve_publickey = server_public_key
self.socket.curve_secretkey = server_private_key
self.socket.curve_server = True

try:
if min_port == max_port:
self.port = min_port
self.socket.bind(f'tcp://*:{min_port}')
else:
self.port = self.socket.bind_to_random_port(
'tcp://*', min_port, max_port)
except (zmq.error.ZMQError, zmq.error.ZMQBindError) as exc:
raise CylcError(f'could not start Cylc ZMQ server: {exc}')

# Keeping srv_public_key_loc as optional arg so as to not break interface
def _socket_connect(self, host, port, srv_public_key_loc=None):
"""Connect socket to stub."""
workflow_srv_dir = get_workflow_srv_dir(self.workflow)
if srv_public_key_loc is None:
# Create new KeyInfo object for the server public key
srv_pub_key_info = KeyInfo(
KeyType.PUBLIC,
KeyOwner.SERVER,
workflow_srv_dir=workflow_srv_dir)

else:
srv_pub_key_info = KeyInfo(
KeyType.PUBLIC,
KeyOwner.SERVER,
full_key_path=srv_public_key_loc)

self.host = host
self.port = port
self.socket = self.context.socket(self.pattern)
self._socket_options()

client_priv_key_info = KeyInfo(
KeyType.PRIVATE,
KeyOwner.CLIENT,
workflow_srv_dir=workflow_srv_dir)
error_msg = "Failed to find user's private key, so cannot connect."
try:
client_public_key, client_priv_key = zmq.auth.load_certificate(
client_priv_key_info.full_key_path)
except (OSError, ValueError):
raise ClientError(error_msg)
if client_priv_key is None: # this can't be caught by exception
raise ClientError(error_msg)
self.socket.curve_publickey = client_public_key
self.socket.curve_secretkey = client_priv_key

# A client can only connect to the server if it knows its public key,
# so we grab this from the location it was created on the filesystem:
try:
# 'load_certificate' will try to load both public & private keys
# from a provided file but will return None, not throw an error,
# for the latter item if not there (as for all public key files)
# so it is OK to use; there is no method to load only the
# public key.
server_public_key = zmq.auth.load_certificate(
srv_pub_key_info.full_key_path)[0]
self.socket.curve_serverkey = server_public_key
except (OSError, ValueError): # ValueError raised w/ no public key
raise ClientError(
"Failed to load the workflow's public key, so cannot connect.")

self.socket.connect(f'tcp://{host}:{port}')

def _socket_options(self):
"""Set socket options.
i.e. self.socket.sndhwm
"""
self.socket.sndhwm = 10000

def _bespoke_start(self):
"""Initiate bespoke items at start."""
self.stopping = False

def stop(self, stop_loop=True):
"""Stop the server.
Args:
stop_loop (Boolean): Stop running IOLoop.
"""
self._bespoke_stop()
if stop_loop and self.loop and self.loop.is_running():
self.loop.stop()
if self.socket and not self.socket.closed:
self.socket.close()
LOG.debug('...stopped')

def _bespoke_stop(self):
"""Bespoke stop items."""
LOG.debug('stopping zmq socket...')
self.stopping = True
# Cylc API version.
# This is the Cylc protocol version number that determines whether a client can
# communicate with a server. This should be changed when breaking changes are
# made for which backwards compatibility can not be provided.
API = 5
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