asimtote 0.16.16

Compare network device configuration files using contextual structures

ASIMTOTE

This package contains two main elements used to compare text-based configuration files (or other files in simple text in a similar format) where they are structured using indented blocks of directives/commands, typically for network devices:

• a parser to read in configuration files and stored them in a dictionary -- the parser utilises the hierarchical nature of the configuration to understand that the same command name might mean different things in different contexts

• a comparator that takes two configuration dictionaries (typically produced by the parser, above) - a source and a target configuration - and writes out a configuration file (or update command set) to transform the source configuration into the destination - this uses a series of 'converters' to handle the difference for each configuration element (e.g. changing the description assigned to an interface)

Each of these are written as abstract base classes that can be inherited from to crete concrete classes for each platform, but the base processing of the parsing and comparing should be consistent, requiring only the specific commands to be handled.

Currently, Cisco IOS is the only concrete platform and only a subset so far (the comparator is still being tweaked to handle this all relatively straightforwardly, before all the commands are implemented). There are currently some odd commands and edge cases which are awkward to handle without some improvements to the core process.

The scripts also support a system whereby 'excludes' can be specified, to exclude those elements of the configuration dictionary which should not be compared, if a known difference exists that cannot be resolved, either as an interim divergence, or a permanent exception.

THE NAME

This package was formerly known as net-contextdiff but has been renamed as it is expected to drop the indented configuration difference mechansim (still using context, but not via indenting).

The new name 'asimtote' is a backronym for something like 'Autonomous System Internetwork Management ...' but the rest has not yet been completed. It's similarity to 'asymptote' is deliberate as it aims to get a configuration into a desired state but will probably never ever get there.

FUTURE DEVELOPMENTS

Longer term, this script may be made unnecessary by other tools but, if it remains, will probably be parsing configurations via something like REST and JSON, rather than by reading legacy text configuration files. It would also be making changes using similar calls rather than generating legacy text conversions. The problem of making changes in the correct order and committing them may still remain, though.

It would also be desirable to separate the parser as this could be useful elsewhere. At the moment, however, it's so intertwined with the converter this would be tedious to maintain and keep in sync. It should probably be made easily usable as a separate component, however.