YANG-based configuration audit

Ok, let's say we operate a network the modern way, which means that:

• We run our network as a code
• We abstract away vendor CLI (and luckily vendor-specific YANG models) by using universal data models
• We use API calls to modify network configuration
• We have BSS/OSS systems to provision services

All of the above means that we don't have to store network devices configuration as unstructured text files anymore. Except one thing — configuration-based audit, which is very useful for migration purposes.

If you already use tools which parse native OS configuration into parameters (my greetings to regexp, TextFSM, CiscoConfParse or TTP lovers), you know that from time to time we have to adopt the script for a syntax change.

In case of big changes in the OS (like Nokia's recent decision to move to MD-CLI syntax), your tools may become obsolete.

But there is a solution for that — we store configuration as structured XML files (sadly far from every network vendors support that).

Then we can just query for requested parameters using XQuery and sudden change of OS syntax is not gonna hurt our tools.