openstack-ansible/doc/source/developer-docs/inventory.rst

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OpenStack-Ansible Inventory

OpenStack-Ansible uses an included script to generate the inventory of hosts and containers within the environment. This script is called by Ansible through its dynamic inventory functionality.

Generating the Inventory

The script that creates the inventory is located at playbooks/inventory/dynamic_inventory.py.

Execution

When running an Ansible command (such as ansible, ansible-playbook or openstack-ansible) Ansible will execute the dynamic_inventory.py script and use its output as inventory.

The command can also be run manually as follows:

# from the playbooks directory
inventory/dynamic_inventory.py --config /etc/openstack_deploy/

This invocation is useful when testing changes to the dynamic inventory script.

Inputs

The dynamic_inventory.py script takes a single argument, --config. If not specified, the default is /etc/openstack_deploy/.

In addition to this argument, the base environment skeleton is provided in the playbooks/inventory/env.d directory of the OpenStack-Ansible codebase.

Note

In all versions prior to , this argument was --file.

The following file must be present in the configuration directory:

• openstack_user_config.yml

Additionally, the configuration or environment could be spread between two additional sub-directories:

• conf.d
• env.d (for environment customization)

The dynamic inventory script does the following:

• Generates the names of each container that runs a service
• Creates container and IP address mappings
• Assigns containers to physical hosts

As an example, consider the following excerpt from openstack_user_config.yml:

identity_hosts:

infra01:

ip: 10.0.0.10

infra02:

ip: 10.0.0.11

infra03:

ip: 10.0.0.12

The identity_hosts dictionary defines an Ansible inventory group named identity_hosts containing the three infra hosts. The configuration file playbooks/inventory/env.d/keystone.yml defines additional Ansible inventory groups for the containers that are deployed onto the three hosts named with the prefix infra.

Note that any services marked with is_metal: true will run on the allocated physical host and not in a container. For an example of is_metal: true being used refer to playbooks/inventory/env.d/cinder.yml in the container_skel section.

Outputs

Once executed, the script will output an openstack_inventory.json file into the directory specified with the --config argument. This is used as the source of truth for repeated runs.

Note

The openstack_inventory.json file is the source of truth for the environment. Deleting this in a production environment means that the UUID portion of container names will be regenerated, which then results in new containers being created. Containers generated under the previous version will no longer be recognized by Ansible, even if reachable via SSH.

The same JSON structure is printed to stdout, which is consumed by Ansible as the inventory for the playbooks.

Checking Inventory Configuration for Errors

Using the --check flag when running dynamic_inventory.py will run the inventory build process and look for known errors, but not write any files to disk.

This check does not do YAML syntax validation, though it will fail if there are unparseable errors.

Inspecting and Managing the Inventory

The file scripts/inventory-manage.py is used to produce human readable output based on the /etc/openstack_deploy/openstack_inventory.json file.

The same script can be used to safely remove hosts from the inventory.

Viewing the Inventory

The /etc/openstack_deploy/openstack_inventory.json file is read by default. An alternative file can be specified with --file.

A list of all hosts can be seen with the --list-host/-l argument

To see a listing of hosts and containers by their group, use --list-groups/-g.

To see all of the containers, use --list-containers/-G.

Removing a Host

A host can be removed with the --remove-item/-r parameter.

Use the host's name as an argument.

Exporting Host Information

Information on a per-host basis can be obtained with the --export/-e parameter.

This JSON output has two top-level keys: hosts and all.

hosts contains a map of a host's name to its variable and group data.

all contains global network information such as the load balancer IPs and provider network metadata.

The lxc_hosts Group

When a container name is created by the dynamic inventory script, the host on which the container resides is added to the lxc_hosts inventory group.

Using this name for a group in the configuration will result in a runtime error.

Dynamic Inventory API documentation

dynamic_inventory

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