Parsers¶

Parsers are responsible for mapping native configuration/data to a YANG model.

Processing data¶

The first thing you have to know is what type of data you are dealing with and then select the appropiate parser. Each one initializes the data and makes it available in similar ways but you have to be aware of the particularities of each one.

You can select the parser with the metadata field:

---
metadata:
    processor: TextTree
    execute:
        - method: cli
          kwargs:
              commands: ["show running-config all"]

That block not only specifies which parser to use but how to retrieve the data necessary for the parser to operate for that particular model.

Available processors are:

Rule Directives¶

name	Available on	description
when	list, container, leaf	If this field is `True` the rule will be executed. Otherwise it won't.
from	list, container, leaf	Under normal circumstances
path	list, container, leaf	Which attributes to advanced. See examples_lists for details.
default	list, container, leaf	If ``path`` fails to resolve assign this value to the resolved object
key	list	Post processing/formatting of the key value
regexp	list, leaf	On lists regexp will be applied over the key. Use it to filter results and capture extra data. On leaves, regexp will assign as value the capture group `value`
pre	leaf	Pre processing/formatting of the value. Useful when you want to statically set it based on ``when`` conditions or from values extracted previously in parent containers/leaves/lists.
value	leaf	Post processing/formatting of the value. Useful when you need to combine data extracted in a regular expression or post-process it with a jinja2 filter to transform the value.
map	leaf	When a map (dictionary) is provided, the value will be resolved using it assigning the new corresponding value.
present	leaf	If `present: yes` value will be `True` if `path` resolves properly. If `present: no` value will be `True` if `path` can't find the attribute. In the rest of the cases the value will be `False`
gate	leaf, container, leaf	If `gate` is present with any value we will stop traversing the tree. This is mostly useful in containers as you can stop processing a branch under conditions where you know you will not find a match.
attribute	leaf	This attribute is specific to the XMLParser. XML documents can add information in the form of attributes. You can complement a `path` with this field to extract the attribute from the element found in `path`.

Keys¶

When a list is traversed you will always have available a key with name $(attribute)_key. In addition, you will have parent_key as the key of the immediate parent object. Example.

Bookmarks¶

Bookmarks are points of interest in the configuration. Usually, you will be gathering blocks of configurations and parsing on those as you progress. However, sometimes the data you need is somewhere else. For those cases you can use the bookmarks within the from field to pick the correct block of configuration.

Bookmarks are created automatically according to these rules:

At the begining of each model a bookmark of name root_$first_attribute_name will point to the list of data that the parser requires. Example
When a container is traversed, a bookmark will be created with name $attribure_name
When a list is traveresed, each element of the list will have its own bookmark with name $attribute_name.$key.

`extra_vars`¶

The regexp directive lets you capture any arbitary amount of information you want. All captured groups will be avaible to you inside the extra_vars.$attribute ($attribute is the attribute where the additional information was captured). Example.