VyOS Networks Blog

Now that the Python library for accessing the running config and the generator of old style templates from new style XML command definitions are known to be functional, it's time to set a cutoff date for the old style code. We decided to arbitrarily set it to May 2018.

Since May the 1st, no new code written in the old style will be accepted. We will accept (and make ourselves) fixes to the old code when the bug severity is high enough to affect VyOS operation, but all new features get to be new style.

If you have some new feature already almost done, consider completing it until May. If you are planning a new feature, consider learning about the new style first.

If you are late to the party, please read these blog posts:

• http://blog.vyos.net/vyos-development-digest-number-10 
• http://blog.vyos.net/vyos-2-dot-0-development-digest-number-7-python-coding-guidelines-for-config-scripts-in-1-dot-2-0-and-config-parser-for-vyconf 
• http://blog.vyos.net/vyos-2-dot-0-development-digest-number-5-doing-1-dot-2-x-and-2-dot-0-development-in-parallel 

For those who are not, I'll reiterate the main points:

• Contributors who know Perl and are still willing to write it are getting progressively harder to find and many people say they would contribute if it wasn't in Perl.
• The reasons people abandoned Perl are more than compelling: lack of proper type checking, exception handling, and many other features of post-60's language designs do not help reliability and ease of maintenance at all.
• Old style handwritten templates are very hard to maintain since both the data and often the logic is spread across dozens, if not hundreds of files in deeply nested directories. Separation of logic from data and a way to keep all command definitions of a feature in a single, observable file are required to make it maintainable.
• With old style templates, there's no way to verify them without installing them on VyOS and trying them by hand. XML is the only common language that has ready to use tools for verification of its syntax and semantics: right now it's already integrated in our build system and a build with malformed command definitions will fail.

I'll write a tutorial about writing features in the new style shortly, stay tuned. Meanwhile you can look at the implementation of cron in 1.2.0:

• https://github.com/vyos/vyos-1x/blob/current/src/conf-mode/vyos-update-crontab.py (conf mode script)
• https://github.com/vyos/vyos-1x/blob/current/interface-definitions/cron.xml (command definitions)