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AVD Plugins & Filters

Arista AVD Plugins

Table of Contents:

Plugin Filters

Arista AVD provides built-in filters to help extend jinja2 templates with functionality and improve code readability.

list_compress filter

The arista.avd.list_compress filter provides the capabilities to compress a list of integers and return as a string for example:

  - [1,2,3,4,5] -> "1-5"
  - [1,2,3,7,8] -> "1-3,7-8"

To use this filter:

{{ list_to_compress | arista.avd.list_compress }}
natural_sort filter

The arista.avd.natural_sort filter provides the capabilities to sort a list or a dictionary of integers and/or strings that contain alphanumeric characters naturally. When leveraged on a dictionary, only the key value will be returned. An optional sort_key can be specified, to sort on content of certain key if the items are dictionaries.

The filter will return an empty list if the value parsed to arista.avd.natural_sort is None or undefined.

To use this filter:

{% for item in dictionary_to_natural_sort | arista.avd.natural_sort %}
{{ natural_sorted_item }}
{% endfor %}

{% for item in list_of_dicts_to_natural_sort | arista.avd.natural_sort('name') %}
{{ dict_sorted_on_name }}
{% endfor %}
default filter

The arista.avd.default filter can provide the same basic capability as the builtin default filter. It will return the input value only if it is valid and if not, provide a default value instead. Our custom filter requires a value to be not undefined and not None to pass through. Furthermore, the filter allows multiple default values as arguments, which will undergo the same validation one after one until we find a valid default value. As a last resort the filter will return None.

To use this filter:

{{ variable | arista.avd.default( default_value_1 , default_value_2 ... ) }}
ethernet segment identifiers management filter

To help provide consistency when configuring EVPN A/A ESI values, the esi_management filter plugin provides an abstraction in the form of a short_esi key. short_esi is an abbreviated 3 octets value to encode Ethernet Segment ID, LACP ID and route target. Transformation from abstraction to network values is managed the following jinja2 filters:

generate_esi filter

The arista.avd.generate_esi filter transforms short_esi: 0303:0202:0101 with prefix 0000:0000 to EVPN ESI: 0000:0000:0303:0202:0101

example:

esi: {{ l2leaf.node_groups[l2leaf_node_group].short_esi | arista.avd.generate_esi }}
generate_lacp_id filter

The arista.avd.generate_lacp_id filter transforms short_esi: 0303:0202:0101 to LACP ID format format: 0303.0202.0101

example:

lacp_id: {{ l2leaf.node_groups[l2leaf_node_group].short_esi | arista.avd.generate_lacp_id }}
generate_route_target filter

The arista.avd.generate_route_target filter transforms short_esi: 0303:0202:0101 to route-target format: 03:03:02:02:01:01

example:

rt: {{ l2leaf.node_groups[l2leaf_node_group].short_esi | arista.avd.generate_route_target }}

Plugin Tests

Arista AVD provides built-in test plugins to help verify data efficiently in jinja2 templates

defined test

The arista.avd.defined test will return False if the passed value is Undefined or None. Else it will return True. arista.avd.defined test also accepts an optional test_value argument to test if the value equals this. The optional var_type argument can be used to also test if the variable is of the expected type.

Optionally the test can emit warnings or errors if the test fails.

Compared to the builtin is defined test, this test will also test for None and can even test for a specific value and/or class.

Syntax:

{% <value> is arista.avd.defined(test_value=<test_value>,
                                 var_type=['float', 'int', 'str', 'list', 'dict', 'tuple'],
                                 fail_action=['warning','error'],
                                 var_name=<string representing name of value>) %}

To use this test:

{% if extremely_long_variable_name is arista.avd.defined %}
text : {{ extremely_long_variable_name }}
{% endif %}
{% if extremely_long_variable_name is arista.avd.defined("something") %}
text : {{ extremely_long_variable_name }}
{% endif %}
Feature is {{ "not " if extremely_long_variable_name is not arista.avd.defined }}configured

The arista.avd.defined test can be useful as an alternative to:

{% if extremely_long_variable_name is defined and extremely_long_variable_name is not none %}
text : {{ extremely_long_variable_name }}
{% endif %}
{% if extremely_long_variable_name is defined and extremely_long_variable_name == "something" %}
text : {{ extremely_long_variable_name }}
{% endif %}
Feature is {{ "not " if extremely_long_variable_name is defined and extremely_long_variable_name is not none }}configured

Warnings or Errors can be emitted with the optional arguments fail_action and var_name:

{% if my_dict.my_list[12].my_var is arista.avd.defined(fail_action='warning', var_name='my_dict.my_list[12].my_var' %}
>>> [WARNING]: my_dict.my_list[12].my_var was expected but not set. Output may be incorrect or incomplete!

{% if my_dict.my_list[12].my_var is arista.avd.defined(fail_action='error', var_name='my_dict.my_list[12].my_var' %}
>>> fatal: [DC2-RS1]: FAILED! => {"msg": "my_dict.my_list[12].my_var was expected but not set!"}

{% set my_dict.my_list[12].my_var = 'not_my_value' %}

{% if my_dict.my_list[12].my_var is arista.avd.defined('my_value', fail_action='warning', var_name='my_dict.my_list[12].my_var' %}
>>> [WARNING]: my_dict.my_list[12].my_var was set to not_my_value but we expected my_value. Output may be incorrect or incomplete!

{% if my_dict.my_list[12].my_var is arista.avd.defined('my_value', fail_action='error', var_name='my_dict.my_list[12].my_var' %}
>>> fatal: [DC2-RS1]: FAILED! => {"msg": "my_dict.my_list[12].my_var was set to not_my_value but we expected my_value!"}
contains test

The arista.avd.contains test will test if a list contains one or more of the supplied value(s). The test will return False if either the passed value or the test_values are Undefined or none.

The test accepts either a single test_value or a list of test_values. To use this test:

{% if my_list is arista.avd.contains(item) %}Match{% endif %}

{# or #}

{% if my_list is arista.avd.contains(item_list) %}Match{% endif %}

example The arista.avd.contains is used in the role eos_designs in combination with selectattr to parse the platform_settings list for an element where switch_platform is contained in the platforms attribute.

Data model:

platform_settings:
  - platforms: [default]
    reload_delay:
      mlag: 300
      non_mlag: 330
  - platforms: [ 7280R, 7280R2, 7500R, 7500R2 ]
    tcam_profile: vxlan-routing
    lag_hardware_only: true
    reload_delay:
      mlag: 900
      non_mlag: 1020
  - platforms: [ 7280R3, 7500R3, 7800R3 ]
    reload_delay:
      mlag: 900
      non_mlag: 1020

Jinja template without the selectattr and arista.avd.contains test:

switch:
{% set ns = namespace() %}
{% for platform_setting in platform_settings %}
{%     set ns.platform_defined = false %}
{%     if switch_platform in platform_setting.platforms %}
{%         set ns.platform_defined = true ]}
  platform_settings: {{ platform_setting }}
{%         break; %}
{%     endif %}
{% endfor %}
{% for platform_setting in platform_settings if ns.platform_defined == false %}
{%     if 'default' in platform_setting.platforms %}
  platform_settings: {{ platform_setting }}
{%         break; %}
{%     endif %}
{% endfor %}
Jinja template with the selectattr and arista.avd.contains test:
switch:
  platform_settings: {{ platform_settings | selectattr("platforms", "arista.avd.contains", switch_platform) | first | arista.avd.default(
                        platform_settings | selectattr("platforms", "arista.avd.contains", "default") | first) }}

Modules

Inventory to CloudVision Containers

The arista.avd.inventory_to_container module provides following capabilities: - Transform inventory groups into CloudVision containers topology. - Create list of configlets definition.

It saves everything in a YAML file using destination keyword.

It is a module to build a structure of data to configure a CloudVision server. Output is ready to be passed to arista.cvp to configure CloudVision.

example:

To use this module:

tasks:
  - name: generate intended variables
    tags: [always]
    inventory_to_container:
      inventory: "{{ inventory_file }}"
      container_root: "{{ container_root }}"
      configlet_dir: "intended/configs"
      configlet_prefix: "{{ configlets_prefix }}"
      destination: "{{playbook_dir}}/intended/structured_configs/{{inventory_hostname}}.yml"

Inventory example applied to this example:

all:
  children:
# DC1_Fabric - EVPN Fabric running in home lab
    DC1:
      children:
        DC1_FABRIC:
          children:
            DC1_SPINES:
              hosts:
                DC1-SPINE1:
                DC1-SPINE2:
            DC1_L3LEAFS:
              children:
                DC1_LEAF1:
                  hosts:
                    DC1-LEAF1A:
                    DC1-LEAF1B:
                DC1_LEAF2:
                  hosts:
                    DC1-LEAF2A:
                    DC1-LEAF2B:

Generated output ready to be used by arista.cvp collection:

---
CVP_DEVICES:
  DC1-SPINE1:
    name: DC1-SPINE1
    parentContainerName: DC1_SPINES
    configlets:
        - DC1-AVD_DC1-SPINE1
    imageBundle: []

CVP_CONTAINERS:
  DC1_LEAF1:
    parent_container: DC1_L3LEAFS
  DC1_FABRIC:
    parent_container: Tenant
  DC1_L3LEAFS:
    parent_container: DC1_FABRIC
  DC1_LEAF2:
    parent_container: DC1_L3LEAFS
  DC1_SPINES:
    parent_container: DC1_FABRIC
Build Configuration to publish configlets to CloudVision

The arista.avd.configlet_build_config module provides the following capabilities: - Build arista.cvp.configlet configuration. - Build configuration to publish configlets to Cloudvision.

options:

- configlet_build_config:
    configlet_dir:  "< Directory where configlets are located | Required >"
    configlet_prefix: "< Prefix to append on configlet | Required >"
    destination: "< File where to save information | Optional >"
    configlet_extension: "< File extension to look for | Default 'conf' >"

example:

# tasks file for configlet_build_config
- name: generate intended variables
  tags: [build, provision]
  configlet_build_config:
    configlet_dir: "/path/to/configlets/folder/"
    configlet_prefix: "AVD_"
    configlet_extension: "cfg"
Add Table Of Contents to an existing MarkDown file

The arista.avd.add_toc module provides following capabilities: - Wrapper of md-toc python library - Produce Table of Contents and add to MD file between markers

The module is used in eos_designs to create Table Of Contents for Fabric Documentation. The module is used in eos_cli_config_gen to create Table Of Contents for Device Documentation.

example:

To use this module:

tasks:
- name: Generate TOC for fabric documentation
  add_toc:
    md_file: "{{ root_dir }}/documentation/fabric/{{ fabric_name }}-documentation.md"
    skip_lines: 3 #Default is 0
    #toc_levels: 2
    #toc_marker: '<!-- toc -->'
  delegate_to: localhost
  run_once: true
  check_mode: no
  tags: [build, provision]
YAML Templates to Facts

The arista.avd.yaml_templates_to_facts module is an Ansible Action Plugin providing the following capabilities: - Set Facts based on one or more Jinja2 templates producing YAML output. - Recursively combining output of templates to allow templates to update overlapping parts of the data models. - Facts set by one template will be accessable by the next templates - Returned Facts can be set below a specific root_key - Facts returned templates can be stripped for null values to avoid them overwriting previous set facts

The module is used in eos_designs first to set facts for devices and then to set the structured_configuration variable based on all the eos_designs templates.

The module arguments are:

- yaml_templates_to_facts:
    root_key: < optional root_key name >
    templates:
        # Path to template file
      - template: "< template file >"
        options:
          # Merge strategy for lists for Ansible Combine filter. See Ansible Combine filter for details.
          list_merge: < append (default) | replace | keep | prepend | append_rp | prepend_rp >
          # Filter out keys from the generated output if value is null/none/undefined
          strip_empty_keys: < true (default) | false >

example:

- name: Set AVD facts
  yaml_templates_to_facts:
    templates: "{{ templates.facts }}"
  check_mode: no
  changed_when: False
  tags: [build, provision]

- name: Generate device configuration in structured format
  yaml_templates_to_facts:
    root_key: structured_config
    templates: "{{ templates.structured_config }}"
  check_mode: no
  changed_when: False
  tags: [build, provision]

Role default variables applied to this example:

# Design variables
design:
  type: "l3ls-evpn"

templates:
  # Templates defined per design
  l3ls-evpn:
    facts:
      # Set general "switch.*" variables
      - template: "facts/main.j2"
      # Set design specific "switch.*" variables
      - template: "designs/l3ls-evpn/facts/main.j2"
    structured_config:
      # Render Structured Configuration
      # Base features
      - template: "base/main.j2"
      # MLAG feature
      - template: "mlag/main.j2"
      # Underlay feature
      - template: "designs/l3ls-evpn/underlay/main.j2"
      # Overlay feature
      - template: "designs/l3ls-evpn/overlay/main.j2"
      # L3 Edge feature
      - template: "l3_edge/main.j2"
      # Tenants feature
      - template: "designs/l3ls-evpn/tenants/main.j2"
      # Connected Endpoints feature
      - template: "connected_endpoints/main.j2"
      # Merge custom_structured_configuration last
      - template: "custom-structured-configuration-from-var.j2"
        options:
          list_merge: "{{ custom_structured_configuration_list_merge }}"
          strip_empty_keys: false

Last update: August 27, 2021
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