Fix bug where known but unavailable plugins would not be skipped

Fixes #327

changelogs/fragments/fix_327_unavailable_plugin.yml

@@ -0,0 +1,3 @@
+---
+bugfixes:
+  - Fixed a bug in :code:`monitoring_plugins` where a requested plugin that is **unavailable** would cause a failure even though it is a **known** plugin and should be skipped (#327).

roles/monitoring_plugins/tasks/main.yml

@@ -23,6 +23,15 @@
       paths:
         - "{{ role_path }}/vars"
 
+- name: Make sure that check plugins are requested and that they are defined
+  assert:
+    that:
+      - icinga_monitoring_plugins_check_commands is defined
+      - diff | length == 0
+    fail_msg: "The following requested check command names (variable 'icinga_monitoring_plugins_check_commands') are not recognized as available check plugins on this host: {{ diff }}"
+  vars:
+    diff: "{{ icinga_monitoring_plugins_check_commands | default([]) | difference(icinga_monitoring_plugins_available_packages | map(attribute='name') | list) | difference(['all']) }}"
+
 - name: Clean up variable discrepancy - remove entries
   set_fact:
     icinga_monitoring_plugins_available_packages: "{{ icinga_monitoring_plugins_available_packages | difference(icinga_monitoring_plugins_available_packages_exclude) }}"
@@ -33,15 +42,6 @@
     icinga_monitoring_plugins_available_packages: "{{ icinga_monitoring_plugins_available_packages + icinga_monitoring_plugins_available_packages_include }}"
   when: icinga_monitoring_plugins_available_packages_include is defined
 
-- name: Make sure that check plugins are requested and that they are defined
-  assert:
-    that:
-      - icinga_monitoring_plugins_check_commands is defined
-      - diff | length == 0
-    fail_msg: "The following requested check command names (variable 'icinga_monitoring_plugins_check_commands') are not recognized as available check plugins on this host: {{ diff }}"
-  vars:
-    diff: "{{ icinga_monitoring_plugins_check_commands | default([]) | difference(icinga_monitoring_plugins_available_packages | map(attribute='name') | list) | difference(['all']) }}"
-
 - name: Create list of packages to be installed
   set_fact:
     needed_packages: "{{ icinga_monitoring_plugins_available_packages | map(attribute='pkg_name') if 'all' in icinga_monitoring_plugins_check_commands else (needed_packages | default([]) + (icinga_monitoring_plugins_available_packages | selectattr('name','equalto', item) | map(attribute='pkg_name') | list)) | unique }}"