Nolan Brubaker 7b288eafbe Use in-tree env.d files, provide override support

In past versions, upgrading OpenStack-Ansible lead to contention between
the code base and deployer customizations when env.d files were changed.
Deployers were encouraged to make their customizations, while the
project needed to sometimes adjust architecture. Detecting these
conflicts in an automated way was difficult, since the files were simple
dictionaries and lists, leaving no metadata to describe intent for the
changes.

This change modifies the dynamic inventory system to first use the
in-tree env.d directory as the base environment, then reads in files
from the /etc/openstack_deploy/env.d directory and updates existing keys
with the new values. In this way, the OSA project can modify the
environment and deployers can customize the environment without directly
manipulating the same files.

As part of this change, the env.d directory was moved in to the
playbooks/inventory directory, in order to reduce the path manipulation
done inside of the dynamic_inventory.py script. The example files were
left in the etc/openstack_deploy directory for reference.

Note that this change supports deleting elements by specifying a
empty value, such as an empty list or an empty dictionary.

When overriding, only the path to the values that changed is necessary.
For example, changing the 'is_metal' property for cinder only needs the
following in /etc/openstack_deploy/env.d/cinder.yml:

    container_skel:
      cinder_volumes_container:
        properties:
          is_metal: false

This is instead of the entirity of the container_skel dict or even the
other top-level dicts.

For AIO/gate scenarioes, the env.d copy logic has been removed, as it is
now redundant.

Change-Id: Ic637fa385fd3fec7365fb9bc5e0ff54a7f4c8bee

2016-07-01 16:40:28 +00:00

4.2 KiB

Raw Blame History

Home OpenStack-Ansible Developer Documentation

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 Mitaka, 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.

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.

4.2 KiB Raw Blame History