ansible Ansible: Loops and Conditionals When Condition
Example
Basic Usage
Use the when condition to control whether a task or role runs or is skipped. This is normally used to change play behavior based on facts from the destination system. Consider this playbook:
- hosts: all
tasks:
- include: Ubuntu.yml
when: ansible_os_family == "Ubuntu"
- include: RHEL.yml
when: ansible_os_family == "RedHat"
Where Ubuntu.yml and RHEL.yml include some distribution-specific logic.
Another common usage is to limit results to those in certain Ansible inventory groups. Consider this inventory file:
[dbs]
mydb01
[webservers]
myweb01
And this playbook:
- hosts: all
tasks:
- name: Restart Apache on webservers
become: yes
service:
name: apache2
state: restarted
when: webservers in group_names
This is using the group_names magic variable.
Conditional Syntax and Logic
Single condition
Syntax
when: (condition)
Example
when: ansible_os_family == "Debian"when: ansible_pkg_mgr == "apt"when: myvariablename is defined
Boolean Filter
Example
when: result|failed
Multiple Conditions
Syntax
When: condition1 and/or condition2
Example (simple)
when: ansible_os_family == "Debian" and ansible_pkg_mgr == "apt"
Example (complex)
Use parentheses for clarity or to control precedence. "AND" has a higher precedence than "OR".
Clauses can span lines:
when:
ansible_distribution in ['RedHat', 'CentOS', 'ScientificLinux'] and
(ansible_distribution_version|version_compare('7', '<') or
ansible_distribution_version|version_compare('8', '>='))
or
ansible_distribution == 'Fedora'
or
ansible_distribution == 'Ubuntu' and
ansible_distribution_version|version_compare('15.04', '>=')
Note the use of parentheses to group the "or" in the first distribution check.
