Standard loops

Standard loops in playbooks are often used to easily perform similar tasks multiple times. The syntax for standard loops is very easy: the {{ item }} variable is the placeholder looping over the with_items list. For example, take a look at the following section in the chapter8_4.yml playbook:

      tasks:
        - name: echo loop items
          command: echo {{ item }}
          with_items: ['r1', 'r2', 'r3', 'r4', 'r5']   

It will loop over the five list items with the same echo command:

TASK [echo loop items] *********************************************************
changed: [192.168.199.185] => (item=r1)
changed: [192.168.199.185] => (item=r2)
changed: [192.168.199.185] => (item=r3)
changed: [192.168.199.185] => (item=r4)
changed: [192.168.199.185] => (item=r5)

We will combine the standard loop with the network command module in the chapter8_5.yml playbook to add multiple VLANs to the device:

 tasks:
   - name: add vlans
     eos_config:
       lines:
           - vlan {{ item }}
       provider: "{{ cli }}"
     with_items:
         - 100
         - 200
         - 300

The with_items list can also be read from a variable, which gives greater flexibility to the structure of your playbook:

vars:
  vlan_numbers: [100, 200, 300]
<skip>
tasks:
  - name: add vlans
    eos_config:
      lines:
          - vlan {{ item }}
      provider: "{{ cli }}"
    with_items: "{{ vlan_numbers }}"

The standard loop is a great time saver when it comes to performing redundant tasks in a playbook. It also makes the playbook more readable by reducing the lines required for the task.

In the next section, we will take a look at looping over dictionaries.