ansible - example of doing something if a file exists

output

# the file doesn't exist

TASK: [debug var=foo] *********************************************************
ok: [localhost] => {
    "foo": {
        "changed": false,
        "invocation": {
            "module_args": "path=/tmp/file",
            "module_name": "stat"
        },
        "stat": {
            "exists": false
        }
    }
}

TASK: [do something with file if exists] **************************************
skipping: [localhost]

play.yml

---
- hosts: all
  vars:
    mypath: /tmp/file
  tasks:
    - stat: path={{mypath}}
      register: foo

    - debug: var=foo

    - name: do something with file if exists
      command: cat {{ mypath }}
      when: foo.stat.exists