Adding support to overriding some of the configuration through environment variables.

cachet_url_monitor/configuration.py

@@ -1,10 +1,12 @@
 #!/usr/bin/env python
+import logging
+import time
+
 import abc
 import cachet_url_monitor.status
-import logging
+import os
 import re
 import requests
-import time
 from yaml import load
 
 # This is the mandatory fields that must be in the configuration file in this
@@ -41,28 +43,32 @@ class Configuration(object):
     """
 
     def __init__(self, config_file):
-        # TODO(mtakaki#1|2016-04-28): Accept overriding settings using environment
-        # variables so we have a more docker-friendly approach.
         self.logger = logging.getLogger('cachet_url_monitor.configuration.Configuration')
         self.config_file = config_file
         self.data = load(file(self.config_file, 'r'))
 
         # We need to validate the configuration is correct and then validate the component actually exists.
         self.validate()
-        self.headers = {'X-Cachet-Token': self.data['cachet']['token']}
-        self.status = self.get_current_status(self.data['cachet']['component_id'])
 
-        self.logger.info('Monitoring URL: %s %s' %
+        self.headers = {'X-Cachet-Token': os.environ.get('CACHET_TOKEN') or self.data['cachet']['token']}
-                         (self.data['endpoint']['method'], self.data['endpoint']['url']))
+
-        self.expectations = [Expectaction.create(expectation) for expectation
+        self.endpoint_method = os.environ.get('ENDPOINT_METHOD') or self.data['endpoint']['method']
-                             in self.data['endpoint']['expectation']]
+        self.endpoint_url = os.environ.get('ENDPOINT_URL') or self.data['endpoint']['url']
+        self.endpoint_timeout = os.environ.get('ENDPOINT_TIMEOUT') or self.data['endpoint'].get('timeout')
+
+        self.api_url = os.environ.get('CACHET_API_URL') or self.data['cachet']['api_url']
+        self.component_id = os.environ.get('CACHET_COMPONENT_ID') or self.data['cachet']['component_id']
+        self.metric_id = os.environ.get('CACHET_METRIC_ID') or self.data['cachet'].get('metric_id')
+
+        self.status = self.get_current_status(self.api_url, self.component_id, self.headers)
+
+        self.logger.info('Monitoring URL: %s %s' % (self.endpoint_method, self.endpoint_url))
+        self.expectations = [Expectaction.create(expectation) for expectation in self.data['endpoint']['expectation']]
         for expectation in self.expectations:
             self.logger.info('Registered expectation: %s' % (expectation,))
 
-    def get_current_status(self, component_id):
+    def get_current_status(self, endpoint_url, component_id, headers):
-        get_status_request = requests.get(
+        get_status_request = requests.get('%s/components/%s' % (endpoint_url, component_id), headers=headers)
-            '%s/components/%d' % (self.data['cachet']['api_url'], self.data['cachet']['component_id']),
-            headers=self.headers)
 
         if get_status_request.ok:
             # The component exists.
@@ -112,9 +118,7 @@ class Configuration(object):
             self.previous_status = self.status
 
         try:
-            self.request = requests.request(self.data['endpoint']['method'],
+            self.request = requests.request(self.endpoint_method, self.endpoint_url, timeout=self.endpoint_timeout)
-                                            self.data['endpoint']['url'],
-                                            timeout=self.data['endpoint']['timeout'])
             self.current_timestamp = int(time.time())
         except requests.ConnectionError:
             self.message = 'The URL is unreachable: %s %s' % (
@@ -148,12 +152,9 @@ class Configuration(object):
         """Pushes the status of the component to the cachet server. It will update the component
         status based on the previous call to evaluate().
         """
-        params = {'id': self.data['cachet']['component_id'], 'status':
+        params = {'id': self.component_id, 'status': self.status}
-            self.status}
+        component_request = requests.put('%s/components/%d' % (self.api_url, self.component_id), params=params,
-        component_request = requests.put('%s/components/%d' %
+                                         headers=self.headers)
-                                         (self.data['cachet']['api_url'],
-                                          self.data['cachet']['component_id']),
-                                         params=params, headers=self.headers)
         if component_request.ok:
             # Successful update
             self.logger.info('Component update: status [%d]' % (self.status,))
@@ -167,9 +168,8 @@ class Configuration(object):
         It only will send a request if the metric id was set in the configuration.
         """
         if 'metric_id' in self.data['cachet'] and hasattr(self, 'request'):
-            params = {'id': self.data['cachet']['metric_id'], 'value':
+            params = {'id': self.metric_id, 'value': self.request.elapsed.total_seconds(),
-                self.request.elapsed.total_seconds(), 'timestamp':
+                      'timestamp': self.current_timestamp}
-                          self.current_timestamp}
             metrics_request = requests.post('%s/metrics/%d/points' %
                                             (self.data['cachet']['api_url'],
                                              self.data['cachet']['metric_id']), params=params,

tests/test_configuration.py

@@ -9,6 +9,7 @@ from requests import ConnectionError, HTTPError, Timeout
 sys.modules['requests'] = mock.Mock()
 sys.modules['logging'] = mock.Mock()
 from cachet_url_monitor.configuration import Configuration
+from test.test_support import EnvironmentVarGuard
 
 
 class ConfigurationTest(unittest.TestCase):
@@ -28,6 +29,9 @@ class ConfigurationTest(unittest.TestCase):
 
         sys.modules['requests'].get = get
 
+        self.env = EnvironmentVarGuard()
+        self.env.set('CACHET_TOKEN', 'token2')
+
         self.configuration = Configuration('config.yml')
         sys.modules['requests'].Timeout = Timeout
         sys.modules['requests'].ConnectionError = ConnectionError
@@ -36,6 +40,8 @@ class ConfigurationTest(unittest.TestCase):
     def test_init(self):
         assert len(self.configuration.data) == 3
         assert len(self.configuration.expectations) == 3
+        assert self.configuration.headers == {'X-Cachet-Token': 'token2'}
+        assert self.configuration.api_url == 'https://demo.cachethq.io/api/v1'
 
     def test_evaluate(self):
         def total_seconds():
@@ -120,7 +126,7 @@ class ConfigurationTest(unittest.TestCase):
         def put(url, params=None, headers=None):
             assert url == 'https://demo.cachethq.io/api/v1/components/1'
             assert params == {'id': 1, 'status': 1}
-            assert headers == {'X-Cachet-Token': 'my_token'}
+            assert headers == {'X-Cachet-Token': 'token2'}
 
             response = mock.Mock()
             response.status_code = 200
@@ -134,7 +140,7 @@ class ConfigurationTest(unittest.TestCase):
         def put(url, params=None, headers=None):
             assert url == 'https://demo.cachethq.io/api/v1/components/1'
             assert params == {'id': 1, 'status': 1}
-            assert headers == {'X-Cachet-Token': 'my_token'}
+            assert headers == {'X-Cachet-Token': 'token2'}
 
             response = mock.Mock()
             response.status_code = 300