CHECKBOX

yamlname: "input_CHECKBOXES"
inputs:
 first_checkbox:
   type: CHECKBOX
   name: "Checkbox #1"
   default: "true"
 second_checkbox:
   type: CHECKBOX
   name: "Checkbox #2"
   info: "This is an example description for the checkbox above."
execute_commands:
 - echo $first_checkbox
 - echo $second_checkbox
docker_image_name: "ubuntu"
docker_image_tag: "latest"

Setting default: "true" in the first input ticks the first checkbox by default. The info parameter in the second checkbox input adds a line of explanation.

Custom action with CHECKBOX inputs