Multiprocessing EOF error with build_acl.py
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bouncenz commented
Thank you for the blog and demo code !
Multiprocessing reports an EOF error in the build_acl.py.
I am not a programmer, but keen network engineer learning python and modules for networks.
Looks like Multiprocessing doesn't like the functions of the API being called before the main function test
On a Mac with python3.11, demo installed with git and poetry I get:
python3 build_acl.py
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/spawn.py", line 120, in spawn_main
exitcode = _main(fd, parent_sentinel)
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/spawn.py", line 129, in _main
prepare(preparation_data)
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/spawn.py", line 240, in prepare
_fixup_main_from_path(data['init_main_from_path'])
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/spawn.py", line 291, in _fixup_main_from_path
main_content = runpy.run_path(main_path,
^^^^^^^^^^^^^^^^^^^^^^^^^
File "<frozen runpy>", line 291, in run_path
File "<frozen runpy>", line 98, in _run_module_code
File "<frozen runpy>", line 88, in _run_code
File "/Users/steveh/dev/ip-tools/aerleon_acl_gen_demo/build_acl.py", line 107, in <module>
configs = api.Generate([cisco_asa_policy], definitions)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/steveh/Library/Caches/pypoetry/virtualenvs/aerleon-demo-zxD1BcZm-py3.11/lib/python3.11/site-packages/aerleon/api.py", line 233, in Generate
return _Generate(
^^^^^^^^^^
File "/Users/steveh/Library/Caches/pypoetry/virtualenvs/aerleon-demo-zxD1BcZm-py3.11/lib/python3.11/site-packages/aerleon/api.py", line 256, in _Generate
manager: multiprocessing.managers.SyncManager = context.Manager()
^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/context.py", line 57, in Manager
m.start()
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/managers.py", line 563, in start
self._process.start()
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/process.py", line 121, in start
self._popen = self._Popen(self)
^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/context.py", line 288, in _Popen
return Popen(process_obj)
^^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/popen_spawn_posix.py", line 32, in __init__
super().__init__(process_obj)
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/popen_fork.py", line 19, in __init__
self._launch(process_obj)
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/popen_spawn_posix.py", line 42, in _launch
prep_data = spawn.get_preparation_data(process_obj._name)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/spawn.py", line 158, in get_preparation_data
_check_not_importing_main()
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/spawn.py", line 138, in _check_not_importing_main
raise RuntimeError('''
RuntimeError:
An attempt has been made to start a new process before the
current process has finished its bootstrapping phase.
This probably means that you are not using fork to start your
child processes and you have forgotten to use the proper idiom
in the main module:
if __name__ == '__main__':
freeze_support()
...
The "freeze_support()" line can be omitted if the program
is not going to be frozen to produce an executable.
Traceback (most recent call last):
File "/Users/steveh/dev/ip-tools/aerleon_acl_gen_demo/build_acl.py", line 107, in <module>
configs = api.Generate([cisco_asa_policy], definitions)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/steveh/Library/Caches/pypoetry/virtualenvs/aerleon-demo-zxD1BcZm-py3.11/lib/python3.11/site-packages/aerleon/api.py", line 233, in Generate
return _Generate(
^^^^^^^^^^
File "/Users/steveh/Library/Caches/pypoetry/virtualenvs/aerleon-demo-zxD1BcZm-py3.11/lib/python3.11/site-packages/aerleon/api.py", line 256, in _Generate
manager: multiprocessing.managers.SyncManager = context.Manager()
^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/context.py", line 57, in Manager
m.start()
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/managers.py", line 567, in start
self._address = reader.recv()
^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/connection.py", line 249, in recv
buf = self._recv_bytes()
^^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/connection.py", line 413, in _recv_bytes
buf = self._recv(4)
^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/multiprocessing/connection.py", line 382, in _recv
raise EOFError
EOFError
Wrapping the API functions in a function and then calling from the main function solves the problem.
...
def makeAsaAcl():
# Create an instance of the Naming class
definitions = naming.Naming()
# Use the ParseDefinitionsObject method to parse the "networks" object
definitions.ParseDefinitionsObject(networks, "networks")
# Use the ParseDefinitionsObject method to parse the "services" object
definitions.ParseDefinitionsObject(services, "services")
# Use the Generate method from the api module to generate configurations
# from the "cisco_asa_policy" object, passing in the definitions object
# as an argument
configs = api.Generate([cisco_asa_policy], definitions)
# Render the the ASA configuration from the configs object
acl = configs["cisco_asa_policy.asa"]
# Remove additional blank lines from rendered ACLs
acl = re.sub("\n\n\n", "\n", acl)
return(acl)
if __name__ == "__main__":
# Print the ACL
print(makeAsaAcl()) # no qa