Python 3 compatibility

[tirkarthi]

The project seems to be incompatible with Python 3. You can use the futurize module to generate code that is compatible with 2 and 3. I ran the module across the codebase and the patches as below. Feel free to close this if Python 3 compatibility is not needed. Stage 2 involves using futurize as dependency which might be slight overkill if this is intended to be a CLI used very frequently with respect to startup times.

Stage 1 patch :

--- herald/rules.py	(original)
+++ herald/rules.py	(refactored)
@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+from __future__ import print_function
 import re
 import logging
 
@@ -189,7 +190,7 @@
         try:
             value = float(value)
         except ValueError:
-            print 'value must be of type int or float! value is {}'.format(value)
+            print('value must be of type int or float! value is {}'.format(value))
             raise
 
         for rule in self._parsed_rules:

Stage 2 patch : (Requires future as a dependency since it handles module reorganization)

--- herald/baseplugin.py	(original)
+++ herald/baseplugin.py	(refactored)
@@ -1,7 +1,10 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+from builtins import str
+from builtins import object
 from gevent import monkey
+from future.utils import with_metaclass
 monkey.patch_all()
 
 import time
@@ -37,7 +40,7 @@
             cls.plugins.append(cls)
 
 
-class HeraldBasePlugin(object):
+class HeraldBasePlugin(with_metaclass(PluginMount, object)):
     """
     All plugins should inherit from this class.
 
@@ -45,7 +48,6 @@
     all plugin classes are available as a list in the `plugins` attribute.
 
     """
-    __metaclass__ = PluginMount
 
     def __init__(self, name, *args, **kwargs):
         self.name = name
--- herald/herald.py	(original)
+++ herald/herald.py	(refactored)
@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+from builtins import str
 from gevent import monkey
 monkey.patch_all()
 
--- herald/plugins/fileplugin.py	(original)
+++ herald/plugins/fileplugin.py	(refactored)
@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+from builtins import str
 import json
 from herald.baseplugin import HeraldPlugin
 
--- herald/plugins/httpplugin.py	(original)
+++ herald/plugins/httpplugin.py	(refactored)
@@ -1,10 +1,13 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+from future import standard_library
+standard_library.install_aliases()
+from builtins import str
 from gevent import monkey
 monkey.patch_all()
 
-import urllib2
+import urllib.request, urllib.error, urllib.parse
 import socket
 import json
 from herald.baseplugin import HeraldPlugin
@@ -23,13 +26,13 @@
         self.is_json = kwargs.get('is_json', False)
 
     def run(self, timeout=10):
-        req = urllib2.Request(self.url)
+        req = urllib.request.Request(self.url)
         response = ''
         try:
-            infourl = urllib2.urlopen(req, timeout=timeout)
-        except urllib2.HTTPError as e:
+            infourl = urllib.request.urlopen(req, timeout=timeout)
+        except urllib.error.HTTPError as e:
             self.logger.warning('HTTPError: get failed, http code: %s', e.code)
-        except urllib2.URLError as e:
+        except urllib.error.URLError as e:
             self.logger.critical('URLError: failed to reach a server, '
                                  'reason: %s', e.reason)
         except socket.timeout:
--- herald/rules.py	(original)
+++ herald/rules.py	(refactored)
@@ -1,6 +1,10 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+from __future__ import division
+from builtins import str
+from past.utils import old_div
+from builtins import object
 import re
 import logging
 
@@ -93,7 +97,7 @@
 
         """
         for rule in self.rules:
-            action, pattern = rule.items()[0]
+            action, pattern = list(rule.items())[0]
             if re.match(pattern, str(value)):
                 return action
         else:
@@ -155,7 +159,7 @@
                     threshold = rule['pct']
                     min_resp = rule.get('min_threshold_response', 1)
                 else:
-                    action, threshold = rule.items()[0]
+                    action, threshold = list(rule.items())[0]
 
                 m = re.match(self.op_regex, str(threshold))
                 op, th = m.groups()
@@ -197,7 +201,7 @@
             if action == 'pct':
                 # calculate the percentage of traffic to be sent based on
                 # the threshold. The op value is ignored.
-                pct = int(100 - ((value / float(threshold)) * 100))
+                pct = int(100 - ((old_div(value, float(threshold))) * 100))
                 if pct <= 0:
                     min_resp = rule[3]
                     self.logger.warn('Pct value {} less than 0, responding with min '