Add playbook for running arbitrary health checks

This is useful on its own, and also aids in developing/testing new
checks that are not part of any playbook.

Since the intent when running this playbook is to execute checks, opt
for a less verbose explanation on the error summary.

playbooks/byo/openshift-checks/README.md

@@ -26,6 +26,9 @@ callback plugin summarizes execution errors at the end of a playbook run.
 3. Certificate expiry playbooks ([certificate_expiry](certificate_expiry)) -
    check that certificates in use are valid and not expiring soon.
 
+4. Adhoc playbook ([adhoc.yml](adhoc.yml)) - use it to run adhoc checks.
+   See the [next section](#the-adhoc-playbook) for a usage example.
+
 ## Running
 
 With a [recent installation of Ansible](../../../README.md#setup), run the playbook
@@ -58,6 +61,34 @@ against your inventory file. Here is the step-by-step:
     $ ansible-playbook -i <inventory file> playbooks/byo/openshift-checks/certificate_expiry/default.yaml -v
     ```
 
+### The adhoc playbook
+
+The adhoc playbook gives flexibility to run any check or a custom group of
+checks. What will be run is determined by the `openshift_checks` variable,
+which, among other ways supported by Ansible, can be set on the command line
+using the `-e` flag.
+
+For example, to run the `docker_storage` check:
+
+```console
+$ ansible-playbook -i <inventory file> playbooks/byo/openshift-checks/adhoc.yml -e openshift_checks=docker_storage
+```
+
+To run more checks, use a comma-separated list of check names:
+
+```console
+$ ansible-playbook -i <inventory file> playbooks/byo/openshift-checks/adhoc.yml -e openshift_checks=docker_storage,disk_availability
+```
+
+To run an entire class of checks, use the name of a check group tag, prefixed by `@`. This will run all checks tagged `preflight`:
+
+```console
+$ ansible-playbook -i <inventory file> playbooks/byo/openshift-checks/adhoc.yml -e openshift_checks=@preflight
+```
+
+It is valid to specify multiple check tags and individual check names together
+in a comma-separated list.
+
 ## Running in a container
 
 This repository is built into a Docker image including Ansible so that it can

playbooks/byo/openshift-checks/adhoc.yml

@@ -0,0 +1,6 @@
+---
+- include: ../openshift-cluster/initialize_groups.yml
+
+- include: ../../common/openshift-cluster/std_include.yml
+
+- include: ../../common/openshift-checks/adhoc.yml

playbooks/common/openshift-checks/adhoc.yml

@@ -0,0 +1,12 @@
+---
+- name: OpenShift health checks
+  hosts: oo_all_hosts
+  roles:
+  - openshift_health_checker
+  vars:
+  - r_openshift_health_checker_playbook_context: adhoc
+  post_tasks:
+  - name: Run health checks
+    action: openshift_health_check
+    args:
+      checks: '{{ openshift_checks | default([]) }}'

roles/openshift_health_checker/callback_plugins/zz_failure_summary.py

@@ -101,7 +101,7 @@ class CallbackModule(CallbackBase):
             'Variables can be set in the inventory or passed on the\n'
             'command line using the -e flag to ansible-playbook.\n\n'
         ).format(playbook=self._playbook_file, checks=checks)
-        if context in ['pre-install', 'health']:
+        if context in ['pre-install', 'health', 'adhoc']:
             summary = (  # user was expecting to run checks, less explanation needed
                 '\n'
                 'You may choose to configure or disable failing checks by\n'