Starting in 2.4, users are nudged to move to plugins as opposed to inventory scripts.
Some links on the subject:
- http://docs.ansible.com/ansible/2.4/porting_guide_2.4.html#inventory-plugins
- https://github.com/ansible/ansible/blob/devel/lib/ansible/plugins/inventory/
- https://github.com/ansible/ansible/blob/devel/docs/docsite/rst/plugins/inventory.rst
The old inventory scripts:
Turn off a needed plugin, and watch the inventory fail.
export ANSIBLE_INVENTORY_ENABLED=script
ansible-inventory -i official/inventory.ini --list
[WARNING]: Unable to parse <...>/official/inventory.ini as an inventory source
In this example, it can not parse the contents of the file, because the ini inventory plugin is not available.
export ANSIBLE_INVENTORY_ENABLED=ini
ansible-inventory -i official/inventory.ini --list
That works.
Ansible will not accept an invalid plugin name.
export ANSIBLE_INVENTORY_ENABLED=foobar
[WARNING]: Failed to load inventory plugin, skipping foobar
Some plugin examples do not actually return content containing hosts, but will modify content from another source. The "constructed" plugin is the most important example of this at the current time:
export ANSIBLE_INVENTORY_ENABLED=ini,constructed
ansible-inventory -i plugins/example_hosts/constructed_hosts -i plugins/constructed.config --list
The plugins list allows the first file (defining the hosts) to be interpreted
via the ini plugin. Then the 2nd inventory given by the -i flag
will grok the contents of constructed.config, which modifies the inventory
contents dynamically.
constructed.config sorts the hosts from constructed_hosts into
groups. As a case-in-point, the host websomething is put into the
webservers because its name starts with "web". This is a rule defined
in the constructed.config file.
The "constructed" inventory must be used after any other inventories that it is intended to operate on in the CLI args.
In order to get this to work, you will have to edit the file
plugins/example_openstack/openstack.yml, hard-coding in the path
of your clone of this repo.
VERY IMPORTANT NOTE: you can not name this file something else. It must be
openstack.yml or openstack.yaml or it will fail without any clear reason
why.
You also need to put in your own authentication
credentials into plugins/example_openstack/clouds.yml.
Additional pre-requisites are that you install the shade library, and
that you specifically enable the openstack plugin. That is covered in the
following lines:
pip install shade
export ANSIBLE_INVENTORY_ENABLED=openstack
ansible-inventory -i plugins/example_openstack/openstack.yml --list
This should produce the actual content.
We can verify this content by comparing it to the output of ansible-playbook:
ansible-playbook -i plugins/example_openstack/openstack.yml debugging/hostvars_print.yml
Also, we can compare the output to the old inventory script.
unset ANSIBLE_INVENTORY_ENABLED
export OS_CLIENT_CONFIG_FILE=<cwd>/plugins/example_openstack/clouds.yml
ansible-inventory -i <ansible source location>/contrib/inventory/ec2.py --list
Current testing shows that these methods produce very near the same data, although not exactly the same.
In this case, you have written a plugin yourself, unlike the previous examples which all used plugins vendored with Ansible.
export ANSIBLE_INVENTORY_PLUGINS=$(PWD)/plugins/user_plugins/
ansible-doc -t inventory -l
ansible-doc -t inventory alan
(note, the ansible-doc commands are fixed as of
Ansible PR #31996,
Ansible 2.4.2 or higher is needed)
If that is working, it should be feasible to do the following:
export ANSIBLE_INVENTORY_ENABLED=alan
ansible-inventory -i top_level_file.ini --list
No matter what inventory file you give it in this case, the output should just have a host named "alan".
If you have a folder named inventory_plugins inside your current
working directory, Ansible will use that.
cd plugins/user_plugins_rel/
export ANSIBLE_INVENTORY_ENABLED=alan
ansible-inventory -i foobar.ini --list
result:
ansible-inventory -i foobar.ini --list
{
"_meta": {
"hostvars": {
"alan": {
"ansible_port": 8928
}
}
},
"all": {
"children": [
"ungrouped"
]
},
"ungrouped": {
"hosts": [
"alan"
]
}
}