Add or remove vlans from a trunk port as needed

example_in_jinja.j2

{#  ############################################## fail if add, no longer supported #}
{% if 'add' in interface['value']['switchport']['trunk']['allowed_vlans'] %}
{{ you_cant_use_the_add_statement_anymore }}
{% endif %}
{#  ############################################## remediate the trunk list #}
{% set trunk_vlan_changes = configuration_prechange['matches']['sections'][0]['section_content']|trunk_vlan_remediate(interface['value']['switchport']['trunk']['allowed_vlans']['vlans'],20) %}
{% if 'vlans' in trunk_vlan_changes and trunk_vlan_changes['vlans'] %}
{% set _ = desired.append("switchport trunk allowed vlan %s" % (trunk_vlan_changes['vlans'])) %}
{% endif %}{# vlans #}
{% for entry in trunk_vlan_changes['vlans_add'] %}
{% set _ = desired.append("switchport trunk allowed vlan add %s" % (entry)) %}
{% endfor %}{# vlans_add #}
{% for entry in trunk_vlan_changes['vlans_remove'] %}
{% set _ = desired.append("switchport trunk allowed vlan remove %s" % (entry)) %}
{% endfor %}{# vlans_remove #}
{% endif %}{# allowed-vlans #}
{% endif %}{# switchport trunk #}

test_trunk_lookup.yml

##########################################
- name: "TEST 1> Test just parsing existing"
  set_fact:
    prefix: 'TEST 1>'

- name: "{{ prefix }} Set working configuration"
  set_fact:
    current_config:
    - interface port-channel3
    - description sealb1srt002-channel-po3
    - switchport
    - switchport mode trunk
    - switchport trunk native vlan 5
    - switchport trunk allowed vlan 99-1000,2100-2105,2195-2196,2200-2205
    - switchport trunk allowed vlan add 2295-2296,2300-2305,2395-2396,2400-2405
    - switchport trunk allowed vlan add 2495-2496,2500-2505,2595-2596,2600-2605
    - spanning-tree port type network
    - vpc peer-link

- name: "{{ prefix }} Set expected results"
  set_fact:
    result: "{{ current_config|trunk_vlan_list }}"
    expected_list: "99-1000,2100-2105,2195-2196,2200-2205,2295-2296,2300-2305,2395-2396,2400-2405,2495-2496,2500-2505,2595-2596,2600-2605"

- name: "{{ prefix }} Assert results as expected"
  assert:
    that: result == expected_list

##########################################
- name: "TEST 2> Test both the addition and removal of vlans to an exisiting port"
  set_fact:
    prefix: 'TEST 2>'

- name: "{{ prefix }} Set working configuration"
  set_fact:
    vlans: 1,2,3,99-1000,2100-2105,2195-2196,2200-2205,2295-2296
    current_config:
    - interface port-channel3
    - description sealb1srt002-channel-po3
    - switchport
    - switchport mode trunk
    - switchport trunk native vlan 5
    - switchport trunk allowed vlan 99-1000,2100-2105,2195-2196,2200-2205
    - switchport trunk allowed vlan add 2295-2296,2300-2305,2395-2396,2400-2405
    - switchport trunk allowed vlan add 2495-2496,2500-2505,2595-2596,2600-2605
    - spanning-tree port type network
    - vpc peer-link

- name: "{{ prefix }} Set expected results"
  set_fact:
    result: "{{ current_config|trunk_vlan_remediate(vlans,20) }}"
    expected_vlans: null
    expected_vlans_add:
    - "1-3"
    expected_vlans_remove:
    - "2300-2305,2395-2396"
    - "2400-2405,2495-2496"
    - "2500-2505,2595-2596"
    - "2600-2605"

- name: "{{ prefix }} Assert results as expected"
  assert:
    that: result['vlans'] == expected_vlans and
          result['vlans_add'] == expected_vlans_add and
          result['vlans_remove'] == expected_vlans_remove

##########################################
- name: "TEST 3> Test total removal of vlans from an exisiting port"
  set_fact:
    prefix: 'TEST 3>'

- name: "{{ prefix }} Set working configuration"
  set_fact:
    vlans:
    current_config:
    - interface port-channel3
    - description sealb1srt002-channel-po3
    - switchport
    - switchport mode trunk
    - switchport trunk native vlan 5
    - switchport trunk allowed vlan 99-1000,2100-2105,2195-2196,2200-2205
    - switchport trunk allowed vlan add 2295-2296,2300-2305,2395-2396,2400-2405
    - switchport trunk allowed vlan add 2495-2496,2500-2505,2595-2596,2600-2605
    - spanning-tree port type network
    - vpc peer-link

- name: "{{ prefix }} Set expected results"
  set_fact:
    result: "{{ current_config|trunk_vlan_remediate(vlans,20) }}"
    expected_vlans: null
    expected_vlans_add: []
    expected_vlans_remove:
    - "99-1000,2100-2105"
    - "2195-2196,2200-2205"
    - "2295-2296,2300-2305"
    - "2395-2396,2400-2405"
    - "2495-2496,2500-2505"
    - "2595-2596,2600-2605"

- name: "{{ prefix }} Assert results as expected"
  assert:
    that: result['vlans'] == expected_vlans and
          result['vlans_add'] == expected_vlans_add and
          result['vlans_remove'] == expected_vlans_remove

##########################################
- name: "TEST 4> Test adding all vlans to a new port"
  set_fact:
    prefix: 'TEST 4>'

- name: "{{ prefix }} Set working configuration"
  set_fact:
    vlans: 1,2,3,99-1000,2100-2105,2195-2196,2200-2205,2295-2296
    current_config:
    - interface port-channel3
    - description sealb1srt002-channel-po3
    - switchport
    - switchport mode trunk
    - switchport trunk native vlan 5

- name: "{{ prefix }} Set expected results"
  set_fact:
    result: "{{ current_config|trunk_vlan_remediate(vlans,20) }}"
    expected_vlans: "1-3,99-1000"
    expected_vlans_add:
    - "2100-2105,2195-2196"
    - "2200-2205,2295-2296"
    expected_vlans_remove: []

- name: "{{ prefix }} Assert results as expected"
  assert:
    that: result['vlans'] == expected_vlans and
          result['vlans_add'] == expected_vlans_add and
          result['vlans_remove'] == expected_vlans_remove

trunk_vlan.py

import re
import itertools

def flatten(string):
    """ Given a string of vlans, return a list of ints

    Args:
        string (str): A string of vlans

    Returns:
        list: A list of ints

    """
    new_list = []
    if isinstance(string, basestring):
        if "," in string:
            vlans = string.split(',')
        else:
            vlans = [string]
        for entry in vlans:
            if '-' in entry:
                parts = entry.split('-')
                flat_range = list(range(int(parts[0]), int(parts[1]) + 1))
                new_list.extend(flat_range)
            else:
                try:
                    new_list.append(int(entry))
                except ValueError:
                    return False
    elif type(string) is int:
        try:
            new_list.append(string)
        except ValueError:
            return False
    else:
        return []
    return new_list

def ranges(i):
    """ Build ranges of consecutive numbers

    Args:
        i (list): a list of integers

    Returns:
            list: a list of tuples

    """
    for a, b in itertools.groupby(enumerate(sorted(set(i))), lambda (x, y): y - x):
        b = list(b)
        yield b[0][1], b[-1][1]

def string_from_ranges(ranged):
    """ Build a vlan list string from a list of tuples

    Args:
        ranged (list): A list of tuples

    Returns:
        str: A string of comma delimited vlans

    """
    new_list = []
    for entry in ranged:
        if entry[0] == entry[1]:
            new_list.append(str(entry[0]))
        else:
            new_list.append("%s-%s" % (entry[0], entry[1]))
    return (",").join(new_list)

def splitter(text, length):
    """ Split a comma delimited string into chunks

    Args:
        text (str): A comma delimited string
        length (int): The maximum length of any line

    Return:
        list: A list of line, each at or smaller than the maximum

    """

    words = iter(text.split(','))
    lines, current = [], next(words)
    for word in words:
        if len(current) + 1 + len(word) > length:
            lines.append(current)
            current = word
        else:
            current += "," + word
    lines.append(current)
    return lines

def trunk_vlan_list(current_config):
    """ Returns a list of vlans from a config

    Args:
        current_config (list): A list of lines making up the configuration

    Returns:
        str: A comma delimited list of the vlans

    """
    match_lines = []
    regex = re.compile(r'^switchport trunk allowed vlan (?:add\s)?(?P<vlans>[\d\-,]+)$')
    for line in current_config:
        result = re.match(regex, line)
        if result:
            match_lines.append(result.groupdict()['vlans'])
    if match_lines:
        current_vlan_list = ",".join(match_lines)
    else:
        current_vlan_list = ""
    return current_vlan_list

def trunk_vlan_remediate(current_config, vlan_list, chunk_size):
    """ Propose remediation to right a configuration to the data

    Args:
        current_config (list): The current configuration
        vlan_list (str): The comma delimited list of vlans from the data
        chunk_size (int): The maximum size of each line

    Returns:
        dict:
            vlans: A string to be applied with the
                   switchport trunk allowed vlan command
            vlans_add: A list of strings to be applied with the
                       switchport trunk allowed vlan add command
            vlans_remove: A list of strings to be applied with the
                          switchport trunk allowed vlan remove command

    """
    current_vlan_list = trunk_vlan_list(current_config)
    if current_vlan_list:
        current_vlan_list_flat = flatten(current_vlan_list)
    else:
        current_vlan_list_flat = []
    if vlan_list:
        desired_vlan_list_flat = flatten(vlan_list)
    else:
        desired_vlan_list_flat = []
    add_vlans = [x for x in desired_vlan_list_flat if x not in current_vlan_list_flat]
    if add_vlans:
        add_vlans_with_ranges = string_from_ranges(ranges(add_vlans))
        add_vlan_strings = splitter(add_vlans_with_ranges, chunk_size)
    else:
        add_vlan_strings = []
    remove_vlans = [x for x in current_vlan_list_flat if x not in desired_vlan_list_flat]
    if remove_vlans:
        remove_vlans_with_ranges = string_from_ranges(ranges(remove_vlans))
        remove_vlan_strings = splitter(remove_vlans_with_ranges, chunk_size)
    else:
        remove_vlan_strings = []
    response = {}
    if current_vlan_list:
        response['vlans'] = None
        response['vlans_add'] = add_vlan_strings
        response['vlans_remove'] = remove_vlan_strings
    else:
        response['vlans'] = add_vlan_strings[0]
        response['vlans_add'] = add_vlan_strings[1:]
        response['vlans_remove'] = remove_vlan_strings
    return response

class FilterModule(object):
    def filters(self):
        return {
            'trunk_vlan_remediate': trunk_vlan_remediate,
            'trunk_vlan_list': trunk_vlan_list
        }