Correct way to use fail module and negative conditionals

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1

I am trying to use the fail module at the very beginning of my playbook to check if the target server is a specific distribution and version. This way I can stop the playbook from running early on before any making any chances.

playbook:

`

2

anyone able to help ?

3

    - name: check if target server is CentOS 6 or Ubuntu 14
      fail: msg='unsupported platform detected!'
      when: (ansible_distribution != "CentOS" and
ansible_distribution_major_version != "6") or (ansible_distribution !=
"Ubuntu" and ansible_distribution_major_version != "14")

This logic seems wrong to me. With

   "msg": "distro is CentOS and version is 6"

then your when turns into

  when: (False and False) or (True and True)

aka

  when: False or True

aka True. Right?

I think you want something more like

  when: NOT (CentOS 6 or Ubuntu 14)

than like

  when: (not CentOS 6) or (not Ubuntu 14)

Because you're always going to be not one of those things -- you need to
negate the whole or.

                                      -Josh (jbs@care.com)

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4

Thanks for clarifying that for me Josh.

What I did was create a variable that contains the supported distributions and have my when condition check against it:

`
vars:
supported_distros: “{{ ansible_distribution }} {{ ansible_distribution_major_version }}”

tasks:

  • name: check if server is running a supported distro
    fail: msg=‘Unsupported platform!’
    when: platform not in [“Ubuntu 14”,“CentOS 6”]
    `

That did the tricks!