This Python module parses a block style document into a dict using dissectors. The main goal is to parse Cisco configuration files, but any vendor is supported as long as the configuration format is block style. The dissector uses indentation or end-of-block markers to determine the hierarchical level of each line.

A dissector is a YAML formatted nested list of dicts with any of these keys:

Supported actions are:

Supported groupings are:

Existing values are not overwritten but will be extended as lists.

Default parameters allow parsing of most configuration files, these are examples of exceptions:

The dissector returns a Tree object which is a nested dict with a parser property that references the dissector used. A dissector can be created from a string or a file and can parse an iterable or a file. Multiple dissectors can be registered to the AutoDissector which uses hints to match a dissector to a file. A hint is a regular expression that is unique to the first 15 lines of a file.

confparser.Dissector(stream, name=None) Return a new Dissector object that takes a YAML formatted dissector to parse block style documents. An open file or string object is accepted. The dissector can be optionally named using the name parameter.

confparser.Dissector.from_file(filename, name=None) Alternate constructor that loads a dissector from the specified file.

confparser.Dissector.parse(lines, indent=1, eob=None) Return a new Tree object that contains the parsed document from iterable lines. The number of spaces for an indent is specified by the parameter indent. If a document doesn't use indentation, an end-of-block marker string can be specified.

confparser.Dissector.parse_str(string, indent=1, eob=None) Return a new Tree object that contains the parsed string string.

confparser.Dissector.parse_file(filepath, indent=1, eob=None) Return a new Tree object that contains the parsed file filepath contents.

confparser.AutoDissector(raise_no_match=True) Return a new AutoDissector object that handles automatic selection of parsers based on hints. Set raise_no_match to False to prevent AutoDissector.from_file from raising ValueError when no matching parser is found.

confparser.AutoDissector.register(dissector, hint, **kwarg) Register Dissector object with hint regex and parser keyword arguments.

confparser.AutoDissector.register_map(dissector, function, hint, **kwarg) Register Dissector object with hint regex and parser keyword arguments with function to apply to the parser iteratable, like the map() built-in function.

confparser.AutoDissector.from_file(filename) Return a new Tree object from matching parser for specified file filename. Raises ValueError when no matching parser is found.

confparser.AutoDissector.from_str(string) Return a new Tree object from matching parser for specified string. Raises ValueError when no matching parser is found.

confparser.Tree(parent=None) Subclass of dict. Return a new Tree object.

confparser.Tree.merge_retain(other) Update Tree with dict other and concatenate values in lists of existing keys.

Basic usage of the module:

import confparser

doc = '''
- match: interface (\S+)
  parent: interface
  child:
  - match: ip address (.*)
    name: ipv4
    action: cidr
  - match: standby (\d+) ip (?P<ip>\S+)
    parent: standby
  - match: switchport trunk allowed vlan (\S+)
    name: allowed_vlan
    action: expand
'''
cfg = '''
interface GigabitEthernet1/1/1
 switchport trunk allowed vlan 10-12,15
!
interface Vlan10
 ip address 10.10.10.2 255.255.255.0
 standby 10 ip 10.10.10.1
!
'''
print(confparser.Dissector(doc).parse_str(cfg))

Output:

{
    "interface": {
        "GigabitEthernet1/1/1": {
            "allowed_vlan": [
                "10",
                "11",
                "12",
                "15"
            ]
        },
        "Vlan10": {
            "ipv4": "10.10.10.2/24",
            "standby": {
                "10": {
                    "ip": "10.10.10.1"
                }
            }
        }
    }
}

The dissector can also be easily loaded from a file and a configuration file can be parsed directly without opening a file:

import confparser

dissector = confparser.Dissector.from_file('ios.yaml')
print(dissector.parse_file('sample.cfg'))

The following example loads multiple dissectors from file and registers them to the AutoDissector with regex hints. All configuration files in the current directory are parsed using all available processor cores and the result is written to a JSON formatted file. Note that Python 3.3+ is required to use Pool.map with instance methods.

import confparser
import multiprocessing
import glob
import json

if __name__ == '__main__':
    auto = confparser.AutoDissector()
    auto.register(confparser.Dissector.from_file('ios.yaml'), 'version \d+.\d+$')
    auto.register(confparser.Dissector.from_file('nxos.yaml'), 'version \d+.\d+\(\d+\)', indent=2)
    auto.register(confparser.Dissector.from_file('iosxr.yaml'), '!! IOS XR Configuration')
    pool = multiprocessing.Pool()
    result = pool.map(auto.from_file, glob.glob('*.cfg'), 1)
    with open('output.json', 'w') as f:
        json.dump({tree.source:tree for tree in result if tree}, f, indent=4)

The AutoDissector sets Tree.source to the filename of the parsed file and is used as key in the dictionary comprehention.

Make sure you have Python 2.7+ or 3.2+ installed on your system. Install ipaddress if you are using a 2.7 or 3.2 version. Install PyYAML as this module depends on it using PIP on Linux or macOS:

pip install pyyaml

or on Windows as follows:

python -m pip install pyyaml

or on Ubuntu as follows:

sudo apt-get install python-yaml

To start using this module and run the usage examples above, just copy the directory confparser and the files ios.yaml, nxos.yaml, iosxr.yaml and sample.cfg to your machine.