Added Custom Exception handling with exit status for various failure …

…scenarios (#258)

* Added Exception handling with Custom exceptions and exit status for various failure scenarios

* added additional new line at the beginning for pep8

* Updated print traceback to format traceback to pass the exception traceback to variable

* fixed a typo for querying

tests/test_zdd.py

@@ -2,6 +2,7 @@
 import zdd
 import mock
 import json
+from zdd_exceptions import *
 
 
 class Arguments:
@@ -332,4 +333,4 @@ def test_complete_cur_exception(self):
 
         args = Arguments()
         args.complete_cur = True
-        self.assertRaises(Exception, zdd.do_zdd, args)
+        self.assertRaises(InvalidArgException, zdd.do_zdd, args)

zdd.py

@@ -15,6 +15,8 @@
 import sys
 import subprocess
 from utils import *
+from zdd_exceptions import *
+import traceback
 
 
 logger = logging.getLogger('zdd')
@@ -57,8 +59,12 @@ def query_yes_no(question, default="yes"):
 
 def marathon_get_request(args, path):
     url = args.marathon + path
-    response = requests.get(url, auth=get_marathon_auth_params(args))
-    response.raise_for_status()
+    try:
+        response = requests.get(url, auth=get_marathon_auth_params(args))
+        response.raise_for_status()
+    except requests.exceptions.RequestException:
+        raise MarathonEndpointException(
+            "Error while querying marathon", url, traceback.format_exc())
     return response
 
 
@@ -273,7 +279,13 @@ def max_wait_not_exceeded(max_wait, timestamp):
 def find_tasks_to_kill(args, new_app, old_app, timestamp):
     marathon_lb_urls = get_marathon_lb_urls(args)
     haproxy_count = len(marathon_lb_urls)
-    listeners = fetch_app_listeners(new_app, marathon_lb_urls)
+    try:
+        listeners = fetch_app_listeners(new_app, marathon_lb_urls)
+    except requests.exceptions.RequestException:
+        raise MarathonLbEndpointException(
+            "Error while querying Marathon-LB",
+            marathon_lb_urls,
+            traceback.format_exc())
     while max_wait_not_exceeded(args.max_wait, timestamp):
         time.sleep(args.step_delay)
 
@@ -411,41 +423,57 @@ def safe_delete_app(args, app, new_app):
 
 def delete_marathon_app(args, app):
     url = args.marathon + '/v2/apps' + app['id']
-    response = requests.delete(url,
-                               auth=get_marathon_auth_params(args))
-    response.raise_for_status()
+    try:
+        response = requests.delete(url,
+                                   auth=get_marathon_auth_params(args))
+        response.raise_for_status()
+    except requests.exceptions.RequestException:
+        raise AppDeleteException(
+            "Error while deleting the app", url, traceback.format_exc())
     return response
 
 
 def kill_marathon_tasks(args, ids):
     data = json.dumps({'ids': ids})
     url = args.marathon + "/v2/tasks/delete?scale=true"
     headers = {'Content-Type': 'application/json'}
-    response = requests.post(url, headers=headers, data=data,
-                             auth=get_marathon_auth_params(args))
-    response.raise_for_status()
+    try:
+        response = requests.post(url, headers=headers, data=data,
+                                 auth=get_marathon_auth_params(args))
+        response.raise_for_status()
+    except requests.exceptions.RequestException:
+        # This is App Scale Down, so raising AppScale Exception
+        raise AppScaleException(
+            "Error while scaling the app", url, data, traceback.format_exc())
     return response
 
 
 def scale_marathon_app_instances(args, app, instances):
     url = args.marathon + "/v2/apps" + app['id']
     data = json.dumps({'instances': instances})
     headers = {'Content-Type': 'application/json'}
-
-    response = requests.put(url, headers=headers, data=data,
-                            auth=get_marathon_auth_params(args))
-
-    response.raise_for_status()
+    try:
+        response = requests.put(url, headers=headers, data=data,
+                                auth=get_marathon_auth_params(args))
+        response.raise_for_status()
+    except requests.exceptions.RequestException:
+        # This is App Scale Up, so raising AppScale Exception
+        raise AppScaleException(
+            "Error while scaling the app", url, data, traceback.format_exc())
     return response
 
 
 def deploy_marathon_app(args, app):
     url = args.marathon + "/v2/apps"
     data = json.dumps(app)
     headers = {'Content-Type': 'application/json'}
-    response = requests.post(url, headers=headers, data=data,
-                             auth=get_marathon_auth_params(args))
-    response.raise_for_status()
+    try:
+        response = requests.post(url, headers=headers, data=data,
+                                 auth=get_marathon_auth_params(args))
+        response.raise_for_status()
+    except requests.exceptions.RequestException:
+        raise AppCreateException(
+            "Error while creating the app", url, data, traceback.format_exc())
     return response
 
 
@@ -469,16 +497,20 @@ def set_service_port(app, servicePort):
 
 def validate_app(app):
     if app['id'] is None:
-        raise Exception("App doesn't contain a valid App ID")
+        raise MissingFieldException("App doesn't contain a valid App ID",
+                                    'id')
     if 'labels' not in app:
-        raise Exception("No labels found. Please define the"
-                        "HAPROXY_DEPLOYMENT_GROUP label")
+        raise MissingFieldException("No labels found. Please define the"
+                                    " HAPROXY_DEPLOYMENT_GROUP label",
+                                    'label')
     if 'HAPROXY_DEPLOYMENT_GROUP' not in app['labels']:
-        raise Exception("Please define the "
-                        "HAPROXY_DEPLOYMENT_GROUP label")
+        raise MissingFieldException("Please define the "
+                                    "HAPROXY_DEPLOYMENT_GROUP label",
+                                    'HAPROXY_DEPLOYMENT_GROUP')
     if 'HAPROXY_DEPLOYMENT_ALT_PORT' not in app['labels']:
-        raise Exception("Please define the "
-                        "HAPROXY_DEPLOYMENT_ALT_PORT label")
+        raise MissingFieldException("Please define the "
+                                    "HAPROXY_DEPLOYMENT_ALT_PORT label",
+                                    'HAPROXY_DEPLOYMENT_ALT_PORT')
 
 
 def set_app_ids(app, colour):
@@ -621,12 +653,12 @@ def do_zdd(args, out=sys.stdout):
     previous_deploys = fetch_previous_deploys(args, app)
 
     if len(previous_deploys) > 1:
-        # There is a stuck deploy
+        # There is a stuck deploy or hybrid deploy
         return safe_resume_deploy(args, previous_deploys)
 
     if args.complete_cur or args.complete_prev:
-        raise Exception("Cannot use --complete-cur, --complete-prev"
-                        " flags when config is not hybrid")
+        raise InvalidArgException("Cannot use --complete-cur, --complete-prev"
+                                  " flags when config is not hybrid")
 
     new_app = prepare_deploy(args, previous_deploys, app)
 
@@ -756,7 +788,19 @@ def process_arguments():
     set_request_retries()
     setup_logging(logger, args.syslog_socket, args.log_format, args.log_level)
 
-    if do_zdd(args):
-        sys.exit(0)
-    else:
-        sys.exit(1)
+    try:
+        if do_zdd(args):
+            sys.exit(0)
+        else:
+            sys.exit(1)
+    except Exception as e:
+        if hasattr(e, 'zdd_exit_status'):
+            if hasattr(e, 'error'):
+                logger.exception(str(e.error))
+            else:
+                logger.exception(traceback.print_exc())
+            sys.exit(e.zdd_exit_status)
+        else:
+            # For Unknown Exceptions
+            logger.exception(traceback.print_exc())
+            sys.exit(2)

zdd_exceptions.py

@@ -0,0 +1,81 @@
+""" Exit Status 1 is already used in the script.
+    Zdd returns with exit status 1 when app is not force
+    deleted either through argument or through prompt.
+    Exit Status 2 is used for Unknown Exceptions.
+"""
+
+
+class InvalidArgException(Exception):
+    """ This exception indicates invalid combination of arguments
+        passed to zdd"""
+    def __init__(self, msg):
+        super(InvalidArgException, self).__init__(msg)
+        self.error = msg
+        self.zdd_exit_status = 3
+
+
+class MissingFieldException(Exception):
+    """ This exception indicates required fields which are missing
+        in JSON payload passed to zdd"""
+    def __init__(self, msg, field):
+        super(MissingFieldException, self).__init__(msg)
+        self.error = msg
+        self.missing_field = field
+        self.zdd_exit_status = 4
+
+
+class MarathonLbEndpointException(Exception):
+    """ This excaption indicates issue with one of the marathonlb
+        endpoints specified as argument to Zdd"""
+    def __init__(self, msg, url, error):
+        super(MarathonLbEndpointException, self).__init__(msg)
+        self.msg = msg
+        self.url = url
+        self.error = error
+        self.zdd_exit_status = 5
+
+
+class MarathonEndpointException(Exception):
+    """ This excaption indicates issue with marathon endpoint
+        specified as argument to Zdd"""
+    def __init__(self, msg, url, error):
+        super(MarathonEndpointException, self).__init__(msg)
+        self.msg = msg
+        self.url = url
+        self.error = error
+        self.zdd_exit_status = 6
+
+
+class AppCreateException(Exception):
+    """ This exception indicates there was a error while creating the
+        new App and hence it was not created."""
+    def __init__(self, msg, url, payload, error):
+        super(AppCreateException, self).__init__(msg)
+        self.msg = msg
+        self.error = error
+        self.url = url
+        self.payload = payload
+        self.zdd_exit_status = 7
+
+
+class AppDeleteException(Exception):
+    """ This exception indicates there was a error while deleting the
+        old App and hence it was not deleted """
+    def __init__(self, msg, url, appid, error):
+        super(AppDeleteException, self).__init__(msg)
+        self.msg = msg
+        self.error = error
+        self.url = url
+        self.zdd_exit_status = 8
+
+
+class AppScaleException(Exception):
+    """ This exception indicated there was a error while either scaling up
+        new app or while scaling down old app"""
+    def __init__(self, msg, url, payload, error):
+        super(AppScaleException, self).__init__(msg)
+        self.msg = msg
+        self.error = error
+        self.url = url
+        self.payload = payload
+        self.zdd_exit_status = 9