fixes and new dot format for nested values

README.md

@@ -150,3 +150,65 @@ define command{
 ```
 OK: Status OK.|'Containers'=1;0;1000 'Images'=11;0;0 'NEventsListener'=3;0;0 'NFd'=10;0;0 'NGoroutines'=14;0;0 'SwapLimit'=1;0;0 
 ```
+
+### Docker Container Monitor Example Plugin
+
+`check_http_json.py` is generic enough to read and evaluate rules on any HTTP endpoint that returns JSON. In this example we'll get the status of a specific container using it's ID which camn be found by using the list containers endpoint (`curl http://127.0.0.1:4243/containers/json?all=1`).
+
+##### Connection information
+
+* Host = 127.0.0.1:4243
+* Path = /containers/2356e8ccb3de8308ccb16cf8f5d157bc85ded5c3d8327b0dfb11818222b6f615/json
+
+##### Rules for "aliveness"
+
+* Verify that the key `ID` exists and is equal to the value `2356e8ccb3de8308ccb16cf8f5d157bc85ded5c3d8327b0dfb11818222b6f615`
+* Verify that the key `State.Running` has a value of `True`
+
+#### Service Definition
+
+`localhost.cfg`
+
+```
+
+define service {
+        use                             local-service
+        host_name                       localhost
+        service_description             Docker container liveness check
+        check_command                   check_my_container
+        }
+
+```
+
+#### Command Definition with Arguments
+
+`commands.cfg`
+
+```
+
+define command{
+        command_name    check_my_container
+        command_line    /usr/bin/python /usr/local/nagios/libexec/plugins/check_http_json.py -H 127.0.0.1:4243 -p /containers/2356e8ccb3de8308ccb16cf8f5d157bc85ded5c3d8327b0dfb11818222b6f615/json -q ID,2356e8ccb3de8308ccb16cf8f5d157bc85ded5c3d8327b0dfb11818222b6f615 State.Running,True
+        }
+
+```
+
+#### Sample Output
+
+```
+WARNING: Status check failed, reason: Value True for key State.Running did not match.
+```
+
+The plugin threw a warning because the Container ID I used on my system has the following State object:
+
+```
+ u'State': {...
+            u'Running': False,
+            ...
+```
+
+If I change the command to have the parameter -q parameter `State.Running,False`, the output becomes:
+
+```
+OK: Status OK.
+```

check_http_json.py

@@ -43,15 +43,24 @@ class JsonHelper:
 	def __init__(self, json_data):
 		self.data = json_data
 
-	def equals(self, key, value): return (key in self.data) and (str(self.data[key]) == value)
+	def equals(self, key, value): return self.exists(key) and str(self.get(key)) == value
-	def lte(self, key, value): return (key in self.data) and (str(self.data[key]) <= value)
+	def lte(self, key, value): return self.exists(key) and str(self.get(key)) <= value
-	def gte(self, key, value): return (key in self.data) and (str(self.data[key]) >= value)
+	def gte(self, key, value): return self.exists(key) and str(self.get(key)) >= value
-	def exists(self, key): return key in self.data
+	def exists(self, key): return (self.get(key) != (None, 'not_found'))
-	def get(self, key):
+	def get(self, key, temp_data=''):
-		if key in self.data:
+		"""Can navigate nested json keys with a dot format (Element.Key.NestedKey). Returns (None, 'not_found') if not found"""
-			return self.data[key]
+		if temp_data:
+			data = temp_data
 		else:
-			return ''
+			data = self.data
+
+		if '.' in key:
+			return self.get(key[key.find('.') + 1:], data[key[:key.find('.')]])
+		else:
+			if key in data:
+				return  data[key]
+			else:
+				return (None, 'not_found')
 
 class JsonRuleProcessor:
 	"""Perform checks and gather values from a JSON dict given rules and metrics definitions"""
@@ -73,7 +82,7 @@ class JsonRuleProcessor:
 			for kv in self.rules.key_value_list:
 				k, v = kv.split(',')
 				if (helper.equals(k, v) == False):
-					reason += " Value %s for key %sdid not match." % (v, k)
+					reason += " Value %s for key %s did not match." % (v, k)
 
 		if self.rules.key_lte_list != None:
 			for kv in self.rules.key_lte_list: