The vyos/xml python lib provides operations to read a cache of the XML interface-definitions in order to read node information defined therein: for example in collection information for the configuration dict, it is necessary to know if the node is tag/leaf/multi-valued and if it has defined default values. The current implementation is impressive, but suffers from several outstanding issues that prevent easy extensions, and necessitate workarounds.

A simple revision allows:

• distinguishing between tag nodes and tag node values
• correct defaults under tag node values
• automatic merging of default values with the configuration dictionary
• simplification of various other manipulations of the config dict (key-mangling)

This revision make use of the vyos1x-config reference_tree (T5194) to collect the xml cache, as a convenience: one could build the cache explicitly, as in the original implementation, however this method supports other planned development.

Migration away from the original implementation will be detailed in a sub-task, and will involve dropping various workarounds in favor of get_config_dict(..., with_defaults=True) and other simplifications.