Configuring the inventory¶

In this chapter, you can find the information on how to configure the openstack-ansible dynamic inventory to your needs.

Introduction¶

Common OpenStack services and their configuration are defined by OpenStack-Ansible in the /etc/openstack_deploy/openstack_user_config.yml settings file.

Additional services should be defined with a YAML file in /etc/openstack_deploy/conf.d, in order to manage file size.

The /etc/openstack_deploy/env.d directory sources all YAML files into the deployed environment, allowing a deployer to define additional group mappings. This directory is used to extend the environment skeleton, or modify the defaults defined in the inventory/env.d directory.

To understand how the dynamic inventory works, see Understanding the inventory.

Warning

Never edit or delete the files /etc/openstack_deploy/openstack_inventory.json or /etc/openstack_deploy/openstack_hostnames_ips.yml. This can lead to file corruptions, and problems with the inventory: hosts and container could disappear and new ones would appear, breaking your existing deployment.

Configuration constraints¶

Group memberships¶

When adding groups, keep the following in mind:

A group can contain hosts
A group can contain child groups

However, groups cannot contain child groups and hosts.

The lxc_hosts Group¶

When the dynamic inventory script creates a container name, 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.

Deploying directly on hosts¶

To deploy a component directly on the host instead of within a container, set the is_metal property to true for the container group in the container_skel section in the appropriate file.

The use of container_vars and mapping from container groups to host groups is the same for a service deployed directly onto the host.

Note

The cinder-volume component is deployed directly on the host by default. See the env.d/cinder.yml file for this example.

Example: Running galera on dedicated hosts¶

For example, to run Galera directly on dedicated hosts, you would perform the following steps:

Modify the container_skel section of the env.d/galera.yml file. For example:

container_skel:
  galera_container:
    belongs_to:
      - db_containers
    contains:
      - galera
    properties:
      is_metal: true

Note

To deploy within containers on these dedicated hosts, omit the is_metal: true property.

Assign the db_containers container group (from the preceding step) to a host group by providing a physical_skel section for the host group in a new or existing file, such as env.d/galera.yml. For example:
```
physical_skel:
  db_containers:
    belongs_to:
      - all_containers
  db_hosts:
    belongs_to:
      - hosts
```
Define the host group (db_hosts) in a conf.d/ file (such as galera.yml). For example:
```
db_hosts:
  db-host1:
    ip: 172.39.123.11
  db-host2:
    ip: 172.39.123.12
  db-host3:
    ip: 172.39.123.13
```
Note

Each of the custom group names in this example (db_containers and db_hosts) are arbitrary. Choose your own group names, but ensure the references are consistent among all relevant files.

Deploying 0 (or more than one) of component type per host¶

When OpenStack-Ansible generates its dynamic inventory, the affinity setting determines how many containers of a similar type are deployed on a single physical host.

Using shared-infra_hosts as an example, consider this openstack_user_config.yml configuration:

shared-infra_hosts:
  infra1:
    ip: 172.29.236.101
  infra2:
    ip: 172.29.236.102
  infra3:
    ip: 172.29.236.103

Three hosts are assigned to the shared-infra_hosts group, OpenStack-Ansible ensures that each host runs a single database container, a single Memcached container, and a single RabbitMQ container. Each host has an affinity of 1 by default, which means that each host runs one of each container type.

If you are deploying a stand-alone Object Storage (swift) environment, you can skip the deployment of RabbitMQ. If you use this configuration, your openstack_user_config.yml file would look as follows:

shared-infra_hosts:
  infra1:
    affinity:
      rabbit_mq_container: 0
    ip: 172.29.236.101
  infra2:
    affinity:
      rabbit_mq_container: 0
    ip: 172.29.236.102
  infra3:
    affinity:
      rabbit_mq_container: 0
    ip: 172.29.236.103

This configuration deploys a Memcached container and a database container on each host, but no RabbitMQ containers.

Omit a service or component from the deployment¶

To omit a component from a deployment, you can use one of several options:

Remove the physical_skel link between the container group and the host group by deleting the related file located in the env.d/ directory.
Do not run the playbook that installs the component. Unless you specify the component to run directly on a host by using the is_metal property, a container is created for this component.
Adjust the Deploying 0 (or more than one) of component type per host to 0 for the host group. Similar to the second option listed here, Unless you specify the component to run directly on a host by using the is_metal property, a container is created for this component.

Deploying using a different container technology¶

Note

While nspawn is an available containerization technology it should be considered experemental at this time. Even though this subsystem is not yet recommended for production, it is stable enough to introduce to the community and something we’d like feedback on as we improve it over the next cycle.

OpenStack-Ansible presently supports two different container technologies, LXC and nspawn. These two container technologies can be used separately or together within the same cluster but has a limitation of only one setting per host.

Using shared-infra_hosts as an example, consider this openstack_user_config.yml configuration:

shared-infra_hosts:
  infra1:
    ip: 172.29.236.101
    container_vars:
      container_tech: lxc
  infra2:
    ip: 172.29.236.102
    container_vars:
      container_tech: nspawn
  infra3:
    ip: 172.29.236.103

In this example the three hosts are assigned to the shared-infra_hosts group, and will deploy containerized workloads using lxc on infra1, nspawn on infra2, and lxc on infra3. Notice infra3 does not define the container_tech option because it not required. If this option is undefined the value will automatically be set to lxc within the generated inventory. The two supported options for the container_tech configuration variable are lxc or nspawn.