Cisco IOS merge and compare_config should generate an exception

[ktbyers]

No description provided.

[dbarrosop]

Kirk, would it work to use the current running-config, append the changes at the end and use that file to compare?

Worst case, I think the best option would be to return the merge configuration instead of returning an Exception.

[ktbyers]

@dbarrosop No, just appending on to the end of running-config wouldn't work. A merge file could have 'no' commands. It could also have no to entire sections of config. For example, 'no router bgp 10'. You could also have merge config commands that modify a hierarchy 'router bgp 10 > neighbor 1.1.1.1 remote-as 20.

Yes, I think an exception is better than just returning the contents of the merge file. Returning the contents of the merge file gives the user a false sense of confidence (i.e. that it is actually doing a real comparison).

I guess we could prepend it with the message "Config merge not supported on Cisco IOS...returning merge config file contents" so that we made it clear in the output what it was doing. That way you wouldn't get an exception.

[dbarrosop]

Yes, I think an exception is better than just returning the contents of the merge file. Returning the contents of the merge file gives the user a false sense of confidence (i.e. that it is actually doing a real comparison).

You are right. If we are going to throw an Exception I guess it's worth creating a new one, something like UnsupportedByDevice. I don't want to reuse NotImplementedException because that one means we haven't implemented it.

[ktbyers]

Merge operation should not generate this error:

(venv) ~/Documents/Projects/acl_manager$ python zz_napalm.py
Error: Could not open file flash0:/candidate_config.txt for reading

[ktbyers]

@dbarrosop Note, from seeing what other users are expecting here.

I changed my mind on this...I think I am going to implement .compare_config() and a merge operation to just echo the merge_config file (i.e. the changes the end-user submitted) with a comment stating that is what it is doing.

[dbarrosop]

Sounds good to me. Add it to the caveats : )

[ktbyers]

Okay, this is what this looks like on a compare_config() for merge operation.

! Cisco IOS does not support true compare_config() for merge: echo merge file.
+hostname pynet-rtr1z
+logging bufferred 9999

for a merge_file.txt that contains

hostname pynet-rtr1z
logging bufferred 9999

[dbarrosop]

This issue has been 'moved' to napalm-automation/napalm-ios#26