Hooks

OpenShift Ansible allows for operators to execute custom tasks during specific operations through a system called hooks. Hooks allow operators to provide files defining tasks to execute before and/or after specific areas during installations and upgrades. This can be very helpful to validate or modify custom infrastructure when installing/upgrading OpenShift.

It is important to remember that when a hook fails the operation fails. This means a good hook can run multiple times and provide the same results. A great hook is idempotent.

Note: There is currently not a standard interface for hooks. In the future a standard interface will be defined and any hooks that existed previously will need to be updated to meet the new standard.

Using Hooks

Hooks are defined in the hosts inventory file under the nodes:vars section.

Each hook should point to a yaml file which defines Ansible tasks. This file will be used as an include meaning that the file can not be a playbook but a set of tasks. Best practice suggests using absolute paths to the hook file to avoid any ambiguity.

Example inventory variables

[nodes:vars]
# <snip>
openshift_node_upgrade_pre_hook=/usr/share/custom/pre_node.yml
openshift_node_upgrade_hook=/usr/share/custom/node.yml
openshift_node_upgrade_post_hook=/usr/share/custom/post_node.yml
# <snip>

Hook files must be a yaml formatted file that defines a set of Ansible tasks. The file may not be a playbook.

Example hook task file


---
# Trivial example forcing an operator to ack the start of an upgrade
# file=/usr/share/custom/pre_node.yml

- name: note the start of a node upgrade
  debug:
      msg: "Node upgrade of {{ inventory_hostname }} is about to start"

- name: require an operator agree to start an upgrade
  pause:
      prompt: "Hit enter to start the node upgrade"

Available Upgrade Hooks

openshift_node_upgrade_pre_hook

Runs before each node is upgraded.
This hook runs against each node in serial.
If a task needs to run against a different host, said task will need to use delegate_to or local_action.

openshift_node_upgrade_hook

Runs after each node is upgraded but before it's marked schedulable again.
This hook runs against each node in serial.
If a task needs to run against a different host, said task will need to use delegate_to or local_action.

openshift_node_upgrade_post_hook

Runs after each node is upgraded; it's the last node upgrade action.
This hook runs against each node in serial.
If a task needs to run against a different host, said task will need to use delegate_to or local_action.

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