How to do it...

1. Install the Python libraries needed for pyATS:

$ sudo pip3 install pyats genie

2. Create the roles directory and then create the requirements.yml file with the following data:

 $ cat roles/requirements.yml
- src: https://github.com/CiscoDevNet/Ansible-pyats
  scm: git
  name: Ansible-pyats

3. Install the Ansible-pyats role as shown in the following code:

 $ Ansible-galaxy install -r requirements.yml

4. Create a new playbook called pb_validate_pyats.yml and populate it with the following task to collect the ospf neighbor from the wan devices.

---
  - name: Network Validation with pyATS
    hosts: wan
    roles:
      - Ansible-pyats
    vars:
      Ansible_connection: local
    tasks:
      - pyats_parse_command:
          command: show ip ospf neighbor
        register: ospf_output
        vars:
          Ansible_connection: network_cli

5. Update the playbook with the following tasks to extract the data for OSPF peer information:

      - name: "FACT >> Pyats OSPF Info"
        set_fact:
          pyats_ospf_data: "{{ ospf_output.structured.interfaces }}"

      - name: " FACT >> Set OSPF peers"
        set_fact:
          OSPF_PEERS: "{{ wan_l3_links[inventory_hostname] | selectattr('ospf','equalto',true) | list }}"

6. Update the playbook with the following tasks to validate OSPF peers and the OSPF peer state:

      - name: Validate Number of OSPF Peers
        assert:
          that:
            - pyats_ospf_data | length == OSPF_PEERS | length
        loop: "{{ OSPF_PEERS }}"

      - name: Validate All Peers are in Full State
        assert:
          that:
            - pyats_ospf_data[item.name] | json_query('neighbors.*.state') | first == 'FULL/ -'
        loop: "{{ OSPF_PEERS }}"