Merge pull request #132 from Hafsa-Naeem/retry_git_connection

retry after exception (for one case of communicating with GitHub)

Good first example of how a retry can be implemented.

All requested changes have been implemented.

connections/github.py

@@ -10,6 +10,8 @@
 # license: GPLv2
 #
 import datetime
+import time
+
 
 from tools import config, logging
 from github import Github, GithubIntegration
@@ -30,15 +32,25 @@ def get_token():
     with open(private_key_path, 'r') as private_key_file:
         private_key = private_key_file.read()
 
-    # If the config keys are not set, get_access_token will raise a NotImplementedError
-    # Returning NoneType token will stop the connection in get_instance
-    try:
-        github_integration = GithubIntegration(app_id, private_key)
-        # Note that installation access tokens last only for 1 hour, you will need to regenerate them after they expire.
-        _token = github_integration.get_access_token(installation_id)
-    except NotImplementedError as err:
-        logging.error(err)
-        _token = None
+    tries = 3
+    for i in range(tries):
+        # If the config keys are not set, get_access_token will raise a NotImplementedError
+        # Returning NoneType token will stop the connection in get_instance
+        try:
+            github_integration = GithubIntegration(app_id, private_key)
+            # Note that installation access tokens last only for 1 hour,
+            # you will need to regenerate them after they expire.
+            _token = github_integration.get_access_token(installation_id)
+            break
+        except NotImplementedError as err:
+            if i < tries - 1:
+                n = 0.8
+                t = n*(i+1)
+                time.sleep(t)
+                continue
+            else:
+                logging.error(err)
+                _token = None
 
     return _token