kayobe/doc/source/custom-ansible-playbooks.rst

Custom Ansible Playbooks

Kayobe supports running custom Ansible playbooks located outside of the kayobe project. This provides a flexible mechanism for customising a control plane. Access to the kayobe variables is possible, ensuring configuration does not need to be repeated.

Kayobe Custom Playbook API

Explicitly allowing users to run custom playbooks with access to the kayobe variables elevates the variable namespace and inventory to become an interface. This raises questions about the stability of this interface, and the guarantees it provides.

The following guidelines apply to the custom playbook API:

• Only variables defined in the kayobe configuration files under etc/kayobe are supported.
• The groups defined in etc/kayobe/inventory/groups are supported.
• Any change to a supported variable (rename, schema change, default value change, or removal) or supported group (rename or removal) will follow a deprecation period of one release cycle.
• Kayobe's internal roles may not be used.

Note that these are guidelines, and exceptions may be made where appropriate.

Running Custom Ansible Playbooks

Run one or more custom ansible playbooks:

(kayobe) $ kayobe playbook run <playbook>[, <playbook>...]

Playbooks do not by default have access to the Kayobe playbook group variables, filter plugins, and test plugins, since these are relative to the current playbook's directory. This can be worked around by creating symbolic links to the Kayobe repository from the Kayobe configuration.

Packaging Custom Playbooks With Configuration

The kayobe project encourages its users to manage configuration for a cloud using version control, based on the kayobe-config repository. Storing custom Ansible playbooks in this repository makes a lot of sense, and kayobe has special support for this.

It is recommended to store custom playbooks in $KAYOBE_CONFIG_PATH/ansible/. Roles located in $KAYOBE_CONFIG_PATH/ansible/roles/ will be automatically available to playbooks in this directory.

With this directory layout, the following commands could be used to create symlinks that allow access to Kayobe's filter plugins, group variables and test plugins:

cd ${KAYOBE_CONFIG_PATH}/ansible/
ln -s ../../../../kayobe/ansible/filter_plugins/ filter_plugins
ln -s ../../../../kayobe/ansible/group_vars/ group_vars
ln -s ../../../../kayobe/ansible/test_plugins/ test_plugins

These symlinks can even be committed to the kayobe-config Git repository.

Ansible Galaxy

Ansible Galaxy provides a means for sharing Ansible roles. Kayobe configuration may provide a Galaxy requirements file that defines roles to be installed from Galaxy. These roles may then be used by custom playbooks.

Galaxy role dependencies may be defined in $KAYOBE_CONFIG_PATH/ansible/requirements.yml. These roles will be installed in $KAYOBE_CONFIG_PATH/ansible/roles/ when bootstrapping the Ansible control host:

(kayobe) $ kayobe control host bootstrap

And updated when upgrading the Ansible control host:

(kayobe) $ kayobe control host upgrade

Example

The following example adds a foo.yml playbook to a set of kayobe configuration. The playbook uses a Galaxy role, bar.baz.

Here is the kayobe configuration repository structure:

etc/kayobe/
    ansible/
        foo.yml
        requirements.yml
        roles/
    bifrost.yml
...

Here is the playbook, ansible/foo.yml:

---
- hosts: controllers
  roles:
    - name: bar.baz

Here is the Galaxy requirements file, ansible/requirements.yml:

---
- bar.baz

We should first install the Galaxy role dependencies, to download the bar.baz role:

(kayobe) $ kayobe control host bootstrap

Then, to run the foo.yml playbook:

(kayobe) $ kayobe playbook run $KAYOBE_CONFIG_PATH/ansible/foo.yml

Hooks

Warning

Hooks are an experimental feature and the design could change in the future. You may have to update your config if there are any changes to the design. This warning will be removed when the design has been stabilised.

Hooks allow you to automatically execute custom playbooks at certain points during the execution of a kayobe command. The point at which a hook is run is referred to as a target. Please see the list of available targets<Hook Targets>.

Hooks are created by symlinking an existing playbook into the the relevant directory under $KAYOBE_CONFIG_PATH/hooks. Kayobe will search the hooks directory for sub-directories matching <command>.<target>.d, where command is the name of a kayobe command with any spaces replaced with dashes, and target is one of the supported targets for the command.

For example, when using the command:

(kayobe) $ kayobe control host bootstrap

kayobe will search the paths:

• $KAYOBE_CONFIG_PATH/hooks/control-host-bootstrap/pre.d
• $KAYOBE_CONFIG_PATH/hooks/control-host-bootstrap/post.d

Any playbooks listed under the pre.d directory will be run before kayobe executes its own playbooks and any playbooks under post.d will be run after. You can affect the order of the playbooks by prefixing the symlink with a sequence number. The sequence number must be separated from the hook name with a dash. Playbooks with smaller sequence numbers are run before playbooks with larger ones. Any ties are broken by alphabetical ordering.

For example to run the playbook foo.yml after kayobe overcloud host configure, you could do the following:

(kayobe) $ mkdir -p ${KAYOBE_CONFIG_PATH}/hooks/overcloud-host-configure/post.d
(kayobe) $ cd ${KAYOBE_CONFIG_PATH}/hooks/overcloud-host-configure/post.d
(kayobe) $ ln -s ../../../ansible/foo.yml 10-foo.yml

The sequence number for the foo.yml playbook is 10.

Failure handling

If the exit status of any playbook, including built-in playbooks and custom hooks, is non-zero, kayobe will not run any subsequent hooks or built-in kayobe playbooks. Ansible provides several methods for preventing a task from producing a failure. Please see the Ansible documentation for more details. Below is an example showing how you can use the ignore_errors option to prevent a task from causing the playbook to report a failure:

---
- name: Failure example
  hosts: localhost
  tasks:
    - name: Deliberately fail
      fail:
      ignore_errors: true

A failure in the Deliberately fail task would not prevent subsequent tasks, hooks, and playbooks from running.

Targets

The following targets are available for all commands:

all commands

Target	Description
pre	Runs before a kayobe command has start executing
post	Runs after a kayobe command has finished executing