(t) replication spawn error #2766

Update replication code re Py2.7 to Py3.11.
- Modernise previously missed replication imports re Py3.*
- Force bytes format for replication messages and commands.
Zmq requires bytes format.
- Minor modification re Pythnon 3 behaviour re dict.keys(),
we previously relied on an implicit Python 2 behaviour.
- Move to Fstrings for all issue focused files.
- Parameter/return type hinting.
- Removed an unused local variable.
- black format update
- Improve error diagnostic content of receiver failing to
retrieve senders IP address from sent appliance ID.
- Improve debug logging.
- Remove receiver 'latest_snap or b""' argument to improve
readability.
- reduce retry iterations from 10 to 3.
- Remove use of None from within zmq command/message passing:
to help with stricter type hinting.
- remove libzmq socker.set_hwm.
- refactor poll -> poller socks -> events for readability.
- additional explanatory comments re sockets etc.
- Enable tracker on listender_broker, sender, and receiver's
response: improves robustness, and aids in debugging.
- add zmq_version and libzmq_version properties to sender and
receiver.
- adapt iostream behaviour: this differs between Py2.7 & Py3.*.
- Fix existing bug re very low send byte count.
- harmonize on btrfs binary location to fs.btrfs for replication.
- readability refactoring improvements.
- keep receiver self.share/snap naming as str, encode before
send only.
- Avoid logging btrfs data stream contents.
- Set read1() bytes read to 100MB max.

src/rockstor/scripts/scheduled_tasks/send_replica.py

@@ -1,5 +1,5 @@
 """
-Copyright (c) 2012-2020 RockStor, Inc. <http://rockstor.com>
+Copyright (c) 2012-2023 RockStor, Inc. <https://rockstor.com>
 This file is part of RockStor.
 
 RockStor is free software; you can redistribute it and/or modify
@@ -13,7 +13,7 @@
 General Public License for more details.
 
 You should have received a copy of the GNU General Public License
-along with this program. If not, see <http://www.gnu.org/licenses/>.
+along with this program. If not, see <https://www.gnu.org/licenses/>.
 """
 
 import sys
@@ -28,25 +28,27 @@ def main():
     rid = int(sys.argv[1])
     ctx = zmq.Context()
     poll = zmq.Poller()
-    num_tries = 12
+    num_tries = 3
     while True:
         req = ctx.socket(zmq.DEALER)
         poll.register(req, zmq.POLLIN)
-        req.connect("ipc://%s" % settings.REPLICATION.get("ipc_socket"))
-        req.send_multipart(["new-send", b"%d" % rid])
+        ipc_socket = settings.REPLICATION.get("ipc_socket")
+        req.connect(f"ipc://{ipc_socket}")
+        req.send_multipart([b"new-send", f"{rid}".encode("utf-8")])
 
         socks = dict(poll.poll(5000))
         if socks.get(req) == zmq.POLLIN:
             rcommand, reply = req.recv_multipart()
-            if rcommand == "SUCCESS":
+            print(f"rcommand={rcommand}, reply={reply}")
+            if rcommand == b"SUCCESS":
                 print(reply)
                 break
             ctx.destroy(linger=0)
             sys.exit(reply)
         num_tries -= 1
         print(
             "No response from Replication service. Number of retry "
-            "attempts left: %d" % num_tries
+            f"attempts left: {num_tries}"
         )
         if num_tries == 0:
             ctx.destroy(linger=0)