okd/roles/openshift_health_checker/HOWTO_CHECKS.md

OpenShift health checks

This Ansible role contains health checks to diagnose problems in OpenShift environments.

Checks are typically implemented as two parts:

1. a Python module in openshift_checks/, with a class that inherits from OpenShiftCheck.
2. a custom Ansible module in library/, for cases when the modules shipped with Ansible do not provide the required functionality.

The checks are called from Ansible playbooks via the openshift_health_check action plugin. See playbooks/openshift-checks/pre-install.yml for an example.

The action plugin dynamically discovers all checks and executes only those selected in the play.

Checks can determine when they are active by implementing the method is_active. Inactive checks are skipped. This is similar to the when instruction in Ansible plays.

Checks may have tags, which are a way to group related checks together. For instance, to run all preflight checks, pass in the group '@preflight' to openshift_health_check.

Groups are automatically computed from tags.

Groups and individual check names can be used together in the argument list to openshift_health_check.

Look at existing checks for the implementation details.