Replace multi-role checks with action plugin

This approach should make it easier to add new checks without having to
write lots of YAML and doing things against Ansible (e.g.
ignore_errors).

A single action plugin determines what checks to run per each host,
including arguments to the check. A check is implemented as a class with
a run method, with the same signature as an action plugin and module,
and is normally backed by a regular Ansible module.

Each check is implemented as a separate Python file. This allows whoever
adds a new check to focus solely in a single Python module, and
potentially an Ansible module within library/ too.

All checks are automatically loaded, and only active checks that are
requested by the playbook get executed.

1 files changed, 95 insertions, 0 deletions

diff --git a/roles/openshift_health_checker/action_plugins/openshift_health_check.py b/roles/openshift_health_checker/action_plugins/openshift_health_check.py
new file mode 100644
index 000000000..36defde0a
--- /dev/null
+++ b/roles/openshift_health_checker/action_plugins/openshift_health_check.py
@@ -0,0 +1,95 @@
+"""
+Ansible action plugin to execute health checks in OpenShift clusters.
+"""
+# pylint: disable=wrong-import-position,missing-docstring,invalid-name
+import sys
+import os
+
+try:
+    from __main__ import display
+except ImportError:
+    from ansible.utils.display import Display
+    display = Display()
+
+from ansible.plugins.action import ActionBase
+
+# Augment sys.path so that we can import checks from a directory relative to
+# this callback plugin.
+sys.path.insert(1, os.path.dirname(os.path.dirname(__file__)))
+
+from openshift_checks import OpenShiftCheck, OpenShiftCheckException  # noqa: E402
+
+
+class ActionModule(ActionBase):
+
+    def run(self, tmp=None, task_vars=None):
+        result = super(ActionModule, self).run(tmp, task_vars)
+
+        if task_vars is None:
+            task_vars = {}
+
+        if "openshift" not in task_vars:
+            result["failed"] = True
+            result["msg"] = "'openshift' is undefined, did 'openshift_facts' run?"
+            return result
+
+        try:
+            known_checks = self.load_known_checks()
+        except OpenShiftCheckException as e:
+            result["failed"] = True
+            result["msg"] = str(e)
+            return result
+
+        args = self._task.args
+        requested_checks = set(args.get("checks", []))
+
+        unknown_checks = requested_checks - set(known_checks)
+        if unknown_checks:
+            result["failed"] = True
+            result["msg"] = (
+                "One or more checks are unknown: {}. "
+                "Make sure there is no typo in the playbook and no files are missing."
+            ).format(", ".join(unknown_checks))
+            return result
+
+        result["checks"] = check_results = {}
+
+        for check_name in requested_checks & set(known_checks):
+            display.banner("CHECK [{} : {}]".format(check_name, task_vars["ansible_host"]))
+            check = known_checks[check_name]
+
+            if check.is_active(task_vars):
+                try:
+                    r = check.run(tmp, task_vars)
+                except OpenShiftCheckException as e:
+                    r = {}
+                    r["failed"] = True
+                    r["msg"] = str(e)
+            else:
+                r = {"skipped": True}
+
+            check_results[check_name] = r
+
+            if r.get("failed", False):
+                result["failed"] = True
+                result["msg"] = "One or more checks failed"
+
+        return result
+
+    def load_known_checks(self):
+        known_checks = {}
+
+        known_check_classes = set(cls for cls in OpenShiftCheck.subclasses())
+
+        for cls in known_check_classes:
+            check_name = cls.name
+            if check_name in known_checks:
+                other_cls = known_checks[check_name].__class__
+                raise OpenShiftCheckException(
+                    "non-unique check name '{}' in: '{}.{}' and '{}.{}'".format(
+                        check_name,
+                        cls.__module__, cls.__name__,
+                        other_cls.__module__, other_cls.__name__))
+            known_checks[check_name] = cls(module_executor=self._execute_module)
+
+        return known_checks