Chapter 13. Configuring the overcloud with Ansible

The config-download feature is the method that director uses to configure the overcloud. Director uses config-download in conjunction with OpenStack Orchestration (heat) and OpenStack Workflow Service (mistral) to generate the software configuration and apply the configuration to each overcloud node. Although heat creates all deployment data from SoftwareDeployment resources to perform the overcloud installation and configuration, heat does not apply any of the configuration. Heat only provides the configuration data through the heat API. When director creates the stack, a mistral workflow queries the heat API to obtain the configuration data, generate a set of Ansible playbooks, and applies the Ansible playbooks to the overcloud.

As a result, when you run the openstack overcloud deploy command, the following process occurs:

Director generates a set of Ansible playbooks for the config-download process. These playbooks are stored in a working directory in the /var/lib/mistral/. This directory is named after the name of the overcloud, which is overcloud by default.

The working directory contains a set of sub-directories named after each overcloud role. These sub-directories contain all tasks relevant to the configuration of the nodes in the overcloud role. These sub-directories also contain additional sub-directories named after each specific node. These sub-directories contain node-specific variables to apply to the overcloud role tasks. As a result, the overcloud roles within the working directory use the following structure:

─ /var/lib/mistral/overcloud
  |
  ├── Controller
  │   ├── overcloud-controller-0
  |   ├── overcloud-controller-1
  │   └── overcloud-controller-2
  ├── Compute
  │   ├── overcloud-compute-0
  |   ├── overcloud-compute-1
  │   └── overcloud-compute-2
  ...

Each working directory is a local Git repository that records changes after each deployment operation. Use the local Git repositories to track configuration changes between each deployment.

The mistral user in the OpenStack Workflow service (mistral) containers own all files in the /var/lib/mistral/ working directories. You can grant the stack user on the undercloud access to all files in this directory. This helps with performing certain operations within the directory.

During the config-download process, Ansible creates a log file on the undercloud in the config-download working directory.

The openstack overcloud deploy command runs the heat-based provisioning process and then the config-download configuration process. You can also run the command to execute each process individually.

The working directory in /var/lib/mistral/overcloud contains the playbooks and scripts necessary to interact with ansible-playbook directly. This procedure shows how to interact with these files.

The config-download working directory is a local Git repository. Every time a deployment operation runs, director adds a Git commit to the working directory with the relevant changes. You can perform Git operations to view configuration for the deployment at different stages and compare the configuration with different deployments.

Be aware of the limitations of the working directory. For example, if you use Git to revert to a previous version of the config-download working directory, this action affects only the configuration in the working directory. It does not affect the following configurations:

Complete the following steps to compare different commits of the config-download working directory.

You can generate your own config-download files outside of the standard workflow. For example, you can generate the overcloud heat stack using the --stack-only option with the openstack overcloud deploy command so that you can apply the configuration separately. Complete the following steps to create your own config-download files manually.

Use the config-download files and the static inventory file to perform a configuration. To execute the deployment playbook, run the ansible-playbook command:

$ ansible-playbook \
  -i inventory.yaml \
  --private-key ~/.ssh/id_rsa \
  --become \
  ~/config-download/deploy_steps_playbook.yaml

To generate an overcloudrc file manually from this configuration, run the following command:

$ openstack action execution run \
  --save-result \
  --run-sync \
  tripleo.deployment.overcloudrc \
  '{"container":"overcloud"}' \
  | jq -r '.["result"]["overcloudrc.v3"]' > overcloudrc.v3

The following file are important top level files within a config-download working directory.

The playbooks use tagged tasks to control the tasks that they apply to the overcloud. Use tags with the ansible-playbook CLI arguments --tags or --skip-tags to control which tasks to execute. The following list contains information about the tags that are enabled by default:

The deploy_steps_playbook.yaml playbook configures the overcloud. This playbook applies all software configuration that is necessary to deploy a full overcloud based on the overcloud deployment plan.

This section contains a summary of the different Ansible plays used within this playbook. The play names in this section are the same names that are used within the playbook and that are displayed in the ansible-playbook output. This section also contains information about the Ansible tags that are set on each play.

You can now continue your regular overcloud operations.