Check marathon apps minor improvements (#23)

* address last comments in #21

* update changelog

CHANGELOG.md

@@ -4,6 +4,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This CHANGELOG follows the format listed [here](https://github.com/sensu-plugins/community/blob/master/HOW_WE_CHANGELOG.md)
 
 ## [Unreleased]
+### Changed
+- check-marathon-apps.rb: minor fixes and documentation update for this check (@bergerx)
 
 ## [2.3.0] - 2018-03-17
 ### Added

README.md

@@ -23,6 +23,104 @@
 
 ## Usage
 
+### bin/check-marathon-apps.rb
+
+Note: This check is an unconventional one. It won't output a check result as many
+other conventional check scripts, and will publish multiple check results via
+the local sensu agent endpoint, effectively breaks the expectation of 1:1
+mapping between check-definition and check-results.
+
+This plugin checks Marathon apps based on
+https://mesosphere.github.io/marathon/docs/marathon-ui.html#application-status-reference .
+It produces two check results per application. One for the apps `health` and
+another check result for the apps `status`.
+
+Check results can be customised by two ways:
+
+1. Default check result fields thats applied to all will be provided by a
+   default check config. Please see th esource code to see the whole defaults.
+2. Application owners can override check results by using marathon labels. This
+   allows each application to have different fields in the published result.
+   e.g. per app escalation or aggregate can be controlled by applying Marathon
+   labels to the apps.
+
+```
+SENSU_MARATHON_CONTACT = team_a_rotation
+SENSU_MARATHON_AGGREGATE = this_apps_aggregate  # will be applied to both `status` and `health` check results
+SENSU_MARATHON_STATUS_AGGREGATE = status_aggregate  # status result of the app have different aggregate
+SENSU_MARATHON_HEALTH_AGGREGATE = health_aggregate  # health result of the app have different aggregate
+SENSU_MARATHON_STATUS_UNSCHEDULED_STATUS = 0  # Disable the check's fail status for this app when it's in unscheduled state.
+```
+
+The override templates that could be used in marathon app labels are:
+
+```
+SENSU_MARATHON_<check_result_field>  # will be applied all below if not overridden
+SENSU_MARATHON_STATUS_<check_result_field>  # will be applied all status states if not overridden
+SENSU_MARATHON_STATUS_<status_state>_<check_result_field>
+SENSU_MARATHON_HEALTH_<check_result_field>  # will be applied all healt states if not overridden
+SENSU_MARATHON_RESULT_<result_state>_<check_result_field>
+```
+
+Where:
+* `check_result_field` could be any field in json.
+* `status_state` is one of "waiting", "delayed", "suspended", "deploying" or "running".
+* `health_state` is one of "unscheduled", "overcapacity", "staged", "unknown", "unhealthy" or "healthy".
+
+Example run:
+
+```
+$ check-marathon-task.rb
+heckMarathonApps OK: Marathon Apps Status and Health check is running properly
+```
+
+The command output of the check script will always be same independently from
+which apps are being checked, but you'll see 2 check-results per app like these
+in sensu:
+
+```
+{
+  "name": "check_marathon_app_test_status",
+  "executed": 1519305736,
+  "marathon": {
+    "id": "/test",
+    "version": "2018-02-20T15:09:43.086Z",
+    "versionInfo": {
+      "lastScalingAt": "2018-02-20T15:09:43.086Z",
+      "lastConfigChangeAt": "2018-02-20T15:09:43.086Z"
+    },
+    "tasksStaged": 0,
+    "tasksRunning": 1,
+    "tasksHealthy": 1,
+    "tasksUnhealthy": 0
+  },
+  "output": "STATUS Unscheduled - tasksRunning(1), tasksStaged(0), tasksHealthy(1), tasksUnhealthy(0)",
+  "ttl": 10,
+  "source": "marathon",
+  "status": 2
+}
+{
+  "name": "check_marathon_app_test_health",
+  "executed": 1519305736,
+  "marathon": {
+    "id": "/test",
+    "version": "2018-02-20T15:09:43.086Z",
+    "versionInfo": {
+      "lastScalingAt": "2018-02-20T15:09:43.086Z",
+      "lastConfigChangeAt": "2018-02-20T15:09:43.086Z"
+    },
+    "tasksStaged": 0,
+    "tasksRunning": 1,
+    "tasksHealthy": 1,
+    "tasksUnhealthy": 0
+  },
+  "output": "HEALTH Healthy - tasksRunning(1), tasksStaged(0), tasksHealthy(1), tasksUnhealthy(0)",
+  "ttl": 10,
+  "source": "marathon",
+  "status": 0
+}
+```
+
 ## Installation
 
 [Installation and Setup](http://sensu-plugins.io/docs/installation_instructions.html)

bin/check-marathon-apps.rb

@@ -3,7 +3,7 @@
 #   check-marathon-apps
 #
 # DESCRIPTION:
-#   This plugin creates checks results for each Marathon app that is running,
+#   This check script creates checks results for each Marathon app that is running,
 #   and reports the status of the app based on Marathon Application Status Reference.
 #   https://mesosphere.github.io/marathon/docs/marathon-ui.html#application-status-reference
 #
@@ -173,7 +173,7 @@ class MarathonAppsCheck < Sensu::Plugin::Check::CLI
                       '`--default-check-config` will override this one.'
 
   option :sensu_client_url,
-         description: 'Sensu client HTTP URL socket',
+         description: 'Sensu client HTTP URL',
          long: '--sensu-client-url url',
          default: 'http://localhost:3031'
 
@@ -246,7 +246,7 @@ def run
           "tasksHealthy(#{app['tasksHealthy'].to_i}), tasksUnhealthy(#{app['tasksUnhealthy'].to_i})"
 
         # Make sure that check result data types are correct
-        sanitize_check_result(check_result)
+        enforce_sensu_field_types(check_result)
 
         # Send the result to sensu-client HTTP socket
         post_check_result(check_result)
@@ -267,7 +267,7 @@ def check_result_scaffold(app)
     }
   end
 
-  def sanitize_check_result(check_result)
+  def enforce_sensu_field_types(check_result)
     # Force data types of different fields on the check result
     # https://sensuapp.org/docs/latest/reference/checks.html#example-check-definition
     # https://sensuapp.org/docs/latest/reference/checks.html#check-result-specification
@@ -285,7 +285,7 @@ def sanitize_check_result(check_result)
     end
   end
 
-  def get(path)
+  def rest_client(path)
     RestClient.get("#{config[:url]}#{path}",
                    user: config[:username],
                    password: config[:password],
@@ -298,12 +298,12 @@ def get(path)
   def fetch_apps
     # http://mesosphere.github.io/marathon/api-console/index.html
     resources_query = APPS_EMBED_RESOURCES.map { |resource| "embed=#{resource}" }.join('&')
-    parse_json(get("/v2/apps?#{resources_query}"))['apps']
+    parse_json(rest_client("/v2/apps?#{resources_query}"))['apps']
   end
 
   def fetch_queue
     # http://mesosphere.github.io/marathon/api-console/index.html
-    parse_json(get('/v2/queue'))['queue']
+    parse_json(rest_client('/v2/queue'))['queue']
   end
 
   def post_check_result(data)