community.general/examples/playbooks/conditionals_part2.yml

---
# this is a demo of conditional executions using 'when' statements, which can skip
# certain tasks on machines/platforms/etc where they do not apply.  

- hosts: all
  user: root

  vars:
     favcolor: "red"
     dog: "fido"
     cat: "whiskers"
     ssn: 8675309

  tasks:

     - name: "do this if my favcolor is blue, and my dog is named fido"
       action: shell /bin/false
       when: favcolor == 'blue' and dog == 'fido'

     - name: "do this if my favcolor is not blue, and my dog is named fido"
       action: shell /bin/true
       when: favcolor != 'blue' and dog == 'fido'

     - name: "do this if my SSN is over 9000"
       action: shell /bin/true
       when: ssn > 9000

     - name: "do this if I have one of these SSNs"
       action: shell /bin/true
       when:  ssn in [ 8675309, 8675310, 8675311 ]
     
     - name: "do this if a variable named hippo is NOT defined"
       action: shell /bin/true
       when: hippo is not defined

     - name: "do this if a variable named hippo is defined"
       action: shell /bin/true
       when: hippo is defined