constructed - Uses Jinja2 to construct vars and groups based on existing inventory.

New in version 2.4.


  • Uses a YAML configuration file with a valid YAML or .config extension to define var expressions and group conditionals
  • The Jinja2 conditionals that qualify a host for membership.
  • The JInja2 exprpessions are calculated and assigned to the variables
  • Only variables already available from previous inventories or the fact cache can be used for templating.
  • When strict is False, failed expressions will be ignored (assumes vars were missing).


Parameter Choices/Defaults Configuration Comments
compose Default:
create vars from jinja2 expressions
groups Default:
add hosts to group based on Jinja2 conditionals
keyed_groups Default:
add hosts to group based on the values of a variable
strict Default:
If true make invalid entries a fatal error, otherwise skip and continue
Since it is possible to use facts in the expressions they might not always be available and we ignore those errors by default.


# inventory.config file in YAML format
plugin: constructed
strict: False
    var_sum: var1 + var2

    # this variable will only be set if I have a persistent fact cache enabled (and have non expired facts)
    # `strict: False` will skip this instead of producing an error if it is missing facts.
    server_type: "ansible_hostname | regex_replace ('(.{6})(.{2}).*', '\\2')"
    # simple name matching
    webservers: inventory_hostname.startswith('web')

    # using ec2 'tags' (assumes aws inventory)
    development: "'devel' in (ec2_tags|list)"

    # using other host properties populated in inventory
    private_only: not (public_dns_name is defined or ip_address is defined)

    # complex group membership
    multi_group: (group_names|intersection(['alpha', 'beta', 'omega']))|length >= 2

    # this creates a group per distro (distro_CentOS, distro_Debian) and assigns the hosts that have matching values to it,
    # using the default separator "_"
    - prefix: distro
      key: ansible_distribution

    # this creates a group per ec2 architecture and assign hosts to the matching ones (arch_x86_64, arch_sparc, etc)
    - prefix: arch
      key: ec2_architecture





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