The when clause is useful when you need to check the output of a variable or a play execution result and act accordingly. We saw a quick example of the when clause in Chapter 4, The Python Automation Framework – Ansible Basics, when we looked at the Ansible 2.5 best practices structure. If you recall, the task only ran when the network operating system of the device was the Cisco IOS. Let's look at another example of its use in chapter5_1.yml:
--- - name: IOS Command Output hosts: "iosv-devices" gather_facts: false connection: local vars: cli: host: "{{ ansible_host }}" username: "{{ username }}" password: "{{ password }}" transport: cli tasks: - name: show hostname ios_command: commands: - show run | i hostname provider: ...
