Managing route_maps: and prefix_lists:

[rich9474]

I am struggling to understand the best way to handle route_maps and prefix lists in the configuration structure. I will have a number of them, some of which are probably the same across the fabric, some DC, rack or host specific, I am trying to avoid repetition in the config as this makes maintenance difficult. I have tried setting:

route_maps:
  RM-TEST-1:
    sequence_numbers:
      10:
        type: permit
        match: [ 'ip address prefix-list PL-TEST-1' ]

at various levels in my group_vars most places it seems to be completely ignored. If I look at a hosts variables with

ansible hostname-m debug  -a "var=hostvars[inventory_hostname]"

I can see that the route_maps dict is present in hostvars if defined at some levels like the top level fabric.yml or a host specific one, but it never seems to make it into the config. It also seems that if I define route_maps in several places, they are over written not merged.

It was suggested that I use: custom_structured_configuration_route_maps, but that feels wrong to me, although I can't say why.

What are the best practice recommendations to manage route_maps and prefix_lists in AVD in a scalable way? or at least, how do others manage them?

[carlbuchmann]

@rich9474 - Thanks for your patience; we missed this question!

When you leverage the same key route_maps at various levels, you are subject to Ansible variable precedence rules, and the variable closest to the host will win -> https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_variables.html#variable-precedence-where-should-i-put-a-variable.

If you are leveraging eos_designs, you can leverage custom_structured_configuration, with a custom prefix for each level to achieve a merge of configuration.

For example:

# define custom structured configuration prefix for each level in your top-level variable.
custom_structured_configuration_prefix:
  - custom_config_global_
  - custom_config_groupA_
  - custom_config_groupX_
  - custom_config_host_
  - custom_structured_configuration_  # keep default if already in use... 

# In top-level group var i.e group_vars/fabric.yaml
custom_config_global_route_maps:

# In sub group var i.e group_vars/l3leaf.yaml
custom_config_groupA_route_maps:

# In hostvars  var i.e host_vars/leaf1.yaml
custom_config_host_route_maps:

Configuration for all 3 levels will then be merged and you can share common configurations in various group vars.

If you have any further questions or require a live session to review this, please don't hesitate to contact us at [email protected].