ansible.builtin.generator inventory – Uses Jinja2 to construct hosts and groups from patterns

Note

This inventory plugin is part of ansible-core and included in all Ansible installations. In most cases, you can use the short plugin name generator even without specifying the collections: keyword. However, we recommend you use the FQCN for easy linking to the plugin documentation and to avoid conflicting with other collections that may have the same inventory plugin name.

New in version 2.6: of ansible.builtin

Synopsis

  • Uses a YAML configuration file with a valid YAML or .config extension to define var expressions and group conditionals

  • Create a template pattern that describes each host, and then use independent configuration layers

  • Every element of every layer is combined to create a host for every layer combination

  • Parent groups can be defined with reference to hosts and other groups using the same template variables

Parameters

Parameter

Comments

hosts

string

The name key is a template used to generate hostnames based on the layers option. Each variable in the name is expanded to create a cartesian product of all possible layer combinations.

The parents are a list of parent groups that the host belongs to. Each parent item contains a name key, again expanded from the template, and an optional parents key that lists its parents.

Parents can also contain vars, which is a dictionary of vars that is then always set for that variable. This can provide easy access to the group name. E.g set an application variable that is set to the value of the application layer name.

layers

string

A dictionary of layers, with the key being the layer name, used as a variable name in the host name and parents keys. Each layer value is a list of possible values for that layer.

plugin

string / required

token that ensures this is a source file for the ‘generator’ plugin.

Choices:

  • ansible.builtin.generator

  • generator

Examples

# inventory.config file in YAML format
# remember to enable this inventory plugin in the ansible.cfg before using
# View the output using `ansible-inventory -i inventory.config --list`
plugin: ansible.builtin.generator
hosts:
    name: "{{ operation }}_{{ application }}_{{ environment }}_runner"
    parents:
      - name: "{{ operation }}_{{ application }}_{{ environment }}"
        parents:
          - name: "{{ operation }}_{{ application }}"
            parents:
              - name: "{{ operation }}"
              - name: "{{ application }}"
          - name: "{{ application }}_{{ environment }}"
            parents:
              - name: "{{ application }}"
                vars:
                  application: "{{ application }}"
              - name: "{{ environment }}"
                vars:
                  environment: "{{ environment }}"
      - name: runner
layers:
    operation:
        - build
        - launch
    environment:
        - dev
        - test
        - prod
    application:
        - web
        - api

Hint

Configuration entries for each entry type have a low to high priority order. For example, a variable that is lower in the list will override a variable that is higher up.