Add CouchDB service check.

Pretty much the same as how it works in Couchbase with a test.

checks.d/couch.py

@@ -15,6 +15,7 @@ class CouchDb(AgentCheck):
     """
 
     SOURCE_TYPE_NAME = 'couchdb'
+    SERVICE_CHECK_NAME = 'couchdb.can_connect'
 
     def _create_metric(self, data, tags=None):
         overall_stats = data.get('stats', {})
@@ -61,7 +62,21 @@ def get_data(self, server, instance):
         endpoint = '/_stats/'
 
         url = '%s%s' % (server, endpoint)
-        overall_stats = self._get_stats(url, instance)
+
+        # Fetch initial stats and capture a service check based on response.
+        service_check_tags = {'instance:%s' % server}
+        try:
+            overall_stats = self._get_stats(url, instance)
+        except urllib2.URLError as e:
+            self.service_check(self.SERVICE_CHECK_NAME, AgentCheck.CRITICAL,
+                tags=service_check_tags, message=e.reason)
+            raise
+        except Exception as e:
+            self.service_check(self.SERVICE_CHECK_NAME, AgentCheck.CRITICAL,
+                tags=service_check_tags, message=str(e))
+            raise
+        else:
+            self.service_check(self.SERVICE_CHECK_NAME, AgentCheck.OK)
 
         # No overall stats? bail out now
         if overall_stats is None:

tests/test_couch.py

@@ -1,12 +1,12 @@
 import unittest
 from tests.common import load_check
 from nose.plugins.attrib import attr
+from checks import AgentCheck
 
 @attr(requires='couchdb')
 class CouchDBTestCase(unittest.TestCase):
 
-    def testMetrics(self):
-
+    def tetst_metrics(self):
         config = {
             'instances': [{
                 'server': 'http://localhost:5984',
@@ -25,3 +25,35 @@ def testMetrics(self):
         self.assertTrue(type(metrics) == type([]), metrics)
         self.assertTrue(len(metrics) > 3)
         self.assertTrue(len([k for k in metrics if "instance:http://localhost:5984" in k[3]['tags']]) > 3)
+
+    def test_service_checks(self):
+        config = {
+            'instances': [
+                {'server': 'http://localhost:5984'},
+                {'server': 'http://localhost:5985'}]
+        }
+        agentConfig = {
+            'version': '0.1',
+            'api_key': 'toto'
+        }
+
+        self.check = load_check('couch', config, agentConfig)
+        self.check.check(config['instances'][0])
+        try:
+            self.check.check(config['instances'][1])
+        except Exception:
+            pass
+        else:
+            raise Exception('CouchDB instance was expected to fail.')
+
+        service_checks = self.check.get_service_checks()
+        self.assertEqual(len(service_checks), 2)
+
+        ok_svc_check = service_checks[0]
+        self.assertEqual(ok_svc_check['check'], self.check.SERVICE_CHECK_NAME)
+        self.assertEqual(ok_svc_check['status'], AgentCheck.OK)
+
+        cr_svc_check = service_checks[1]
+        self.assertEqual(cr_svc_check['check'], self.check.SERVICE_CHECK_NAME)
+        self.assertEqual(cr_svc_check['status'], AgentCheck.CRITICAL)
+