Ansible playbook to create VLAN if don’t exist on a Cisco switch

Apr102022

The playbook let’s you to check VLAN existing on Cisco switch, if not creating it for you with add interfaces too as optional.

Note: To give you the impression that how to register data obtained from run-config and compare with true and false using when (defined/undefined). In this way, I can give your ideas to use the same mechanism to solve other tasks, otherwise, not need 22.

1. Download and install Ansible Cisco IOS collection on your Linux computer

   ansible-galaxy collection install cisco.ios

2. Create an empty YAML file and name it create_vlan.yaml with below codes:

   # @author [Hawar Koyi]
   # @email [hawar@koyi.it]
   # @create date 2021-04-10 15:20:38
   # @desc [Automation - Check if VLAN existing, if not create it]
   ---
   - name: Create VLAN if don’t exist on a Cisco switch
     hosts: Cisco
     gather_facts: false
     connection: local
   
     #Change variables values
     vars:
       vlan_id: 35
       vlan_name: Guest
       interface: GigabitEthernet0/2
   
     tasks:
   
       #Run show VLAN id "{{ vlan_id }}" and register result.
       - name: Collect facts about VLAN "{{ vlan_id }}" on device
         ios_command:
           commands: show vlan id "{{ vlan_id }}" | section enet
         register: sh_vlan_output
   
      #Check if VLAN it's defined, does not do anything if existing 
       - set_fact:
           vlan_exists: false
         when: sh_vlan_output.stdout_lines is defined
   
      #Check if VLAN it's undefined, if not then go for below task to Add VLAN
       - set_fact:
           vlan_exists: true
         when: sh_vlan_output.stdout_lines is undefined
     
      #Add VLAN with name and interfaces too.
       - name: Add VLAN using aggregate
         cisco.ios.ios_vlan:
           aggregate:
           - {vlan_id: "{{ vlan_id }}", name: "{{ vlan_name }}", interfaces: "{{ interface }}"}
   
      #Save to start-config when modified 
       - name: save running to start-config when modified
         ios_config:
           save_when: modified
   
   #End of codes
   
   

3. Create an empty text file and name it hosts with devices IP-addresses and other details.

   [Cisco]
   192.168.10.122
   192.168.xx.xx
   
   [Cisco:vars]
   ansible_connection=network_cli
   ansible_network_os=ios
   ansible_user=cisco
   ansible_password=cisco
   ansible_become=yes
   ansible_become_method=enable
   ansible_become_password=cisco

4. Finally run the playbook with this command

   ansible-playbook -i hosts create_vlan.yaml

   Results looks like the image below.
   

   Extra if you want. Trunk an interface

   #Make Gi0/2 mode as trunk
   - name: Merge provided configuration with device configuration
     cisco.ios.ios_l2_interfaces:
       config:
       - name: GigabitEthernet0/2
         mode: trunk
         trunk:
           allowed_vlans: 10-20,40
           native_vlan: 20
           pruning_vlans: 10,20
           encapsulation: dot1q
       state: merged

   For more information, check out here: For VLAN cisco.ios.ios_vlan and for Interfaces cisco.ios.ios_l2_interfaces