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ansible
Ken Jenney
Ken Jenney

Reputation: 522

Ansible Test what a Variable Begins with

I need to be able to install a MySQL library. Python has 1 package for v2 and another for v3. I need to be able to tell Ansible which package to install. 

- name: Ensure MySQL-python is installed
  pip:
    name: MySQL-python
    state: present
  become: true
  when: python_version is regex("^2.*")

- name: Ensure mysqlclient is installed
  pip:
    name: mysqlclient
    state: present
  become: true
  when: python_version is regex("^3.*")

The regular expression is valid but Ansible is skipping them both even though this:

- debug:
    var: python_version

returns this:

TASK [debug] ****************************************************************************************************************************************************************
ok: [localhost] => {
    "python_version": "2.7.10"
}

Upvotes: 3

Views: 13511

Answers (2)

Vladimir Botka
Vladimir Botka

Reputation: 68124

regex works for me with ansible 2.7.9. The example below

      vars:
        python_version: "2.7.10"
      tasks:
        - debug:
            msg: Python version 2
          when: python_version is regex('^2.*')

gives

    "msg": "Python version 2"

Version Comparison is more convenient for complex tests. The example below gives the same result.

        - debug:
            msg: Python version 2
          when:
            - python_version is version('2', '>=')
            - python_version is version('3', '<')

The test regex is documented in Ansible 2.8 for the first time. In earlier versions, only the tests search and match are documented. In the current source the tests search and match are implemented on top of regex

    def match(value, pattern='', ignorecase=False, multiline=False):
        return regex(value, pattern, ignorecase, multiline, 'match')

    def search(value, pattern='', ignorecase=False, multiline=False):
        return regex(value, pattern, ignorecase, multiline, 'search')

Upvotes: 7

Markus
Markus

Reputation: 3148

Like Vladimir said.
Another improvement might be the source of python_version. When using gather_facts you can do it without regexp.

---
- hosts: localhost
  gather_facts: True

  tasks:

    - name: do some stuff
      debug:
        msg: do something because it is python 3
      when: ansible_facts.python.version.major is version('3', '=')

    - name: do other stuff
      debug:
        msg: I don't support legacy software
      when: ansible_facts.python.version.major is version('2', '=')

Upvotes: 1

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