In my team we are using several custom modules based on network_cli / cliconf.
For one of our manufacturer, we have a issue with the method “_find_prompt” of the “network_cli.py”, we would like to know if its possible to overload “network_cli.py” and how ?
For now, we put a modified “network_cli.py” on the module folder called “connection_plugins”, but we would like to only overload the method “_find_prompt”.
About the issue that we face :
In a custom module, you have to set, in the terminal_plugins, some info about the “stderr” and “stdout”.
For example :
stderr = “command unknown”
stdout = “MyPrompt >”
When stderr match, an error should be raise.
And the data are catched until the “stdout” match.
When you have a chunk of data like : [“Command unknown”, “MyPrompt >”]
=> No problem, an error is raise
BUT, when you have several chunk of data like :
1st chunk : [“Command unknown”, “Lorem”, “ipsum”]
2st chunk : [“Lorem2”, “MyPrompt >”]
In this case no error is raise !
So I have two questions
How to deal with this kind of behaviour ?
How to overload a specific function in “network_cli.py” ?
From Ansible version 2.9 onwards you can configure a list of terminal regex (ansible_terminal_stderr_re and ansible_terminal_stdout_re) to identify if the response is an error or valid output.
In this case no error is raise, because between the 2 chunk, the variable : is_error_message is set to False
In network_cli.py
def receive([...])
[...]
if self._find_prompt(window): # window = chunk of data
expected True; else still wait chunk of data
def _find_prompt(self, response):
'''Searches the buffered response for a matching command prompt
'''
errored_response = None
is_error_message = False
for regex in self._terminal_stderr_re: # First chunk - match / Second chunk - no match
if regex.search(response):
is_error_message = True
# Check if error response ends with command prompt if not
# receive it buffered prompt
for regex in self._terminal_stdout_re: # First chunk - no match - so errored_response is not set
match = regex.search(response)
if match:
errored_response = response
self._matched_pattern = regex.pattern
self._matched_prompt = match.group()
self._log_messages("matched error regex '%s' from response '%s'" % (self._matched_pattern, errored_response))
break
if not is_error_message: # Second chunk, is_error_message was reset to False, so the condition are True.
for regex in self._terminal_stdout_re:
match = regex.search(response)
if match:
self._matched_pattern = regex.pattern
self._matched_prompt = match.group()
self._log_messages("matched cli prompt '%s' with regex '%s' from response '%s'" % (self._matched_prompt, self._matched_pattern, response))
if not errored_response:
return True # Finally return "Everything is okkayyy"
if errored_response: # First chunk - errored_response is still None -> not triggered - no error raise
raise AnsibleConnectionFailure(errored_response)
return False
That's why I would like to overload this method.
The regex match is done for each chunk (256 bytes) received to identify if the chunk has error/prompt string.
Based on your problem description, if the first chunk matches the error regex it will raise an error exception and not read second chunk at all.
However, if the error string is split across two chunks, in that case, it might not detect the error string as the default error regex won’t match.
For such case regex can be configured to handle this scenario
Ah, I missed your earlier email.
Yes, that’s right observation. One way to get around the issue is to configure the ansible_terminal_stdout_re for a given task to match the error and prompt in first chunk itself.
However, I agree that is not the best of the solution.
Please raise an issue here https://github.com/ansible-collections/ansible.netcommon/issues to track it.
