ref(models): use DRF APIException as a base for all exceptions

Move to using DeisException that extends APIException (with 400 as a status code) instead of EnvironmentError, have AlreadyExists extend APIException with 409 and KubeException and Logger related exceptions get raised up to the view as ServiceUnavailable

Additionally using "from e" when re-raising exception to keep contextual information if that is ever required (https://www.python.org/dev/peps/pep-3134/)

https://github.com/tomchristie/django-rest-framework/blob/master/docs/api-guide/exceptions.md has further info on DRF exceptions

ref #612

Author: helgi

rootfs/api/models/__init__.py

@@ -13,16 +13,27 @@
 from django.db import models
 from django.db.models.signals import post_delete, post_save
 from django.dispatch import receiver
-from django.core.exceptions import ValidationError
+
+from rest_framework.exceptions import ValidationError, APIException
 from rest_framework.authtoken.models import Token
 
 from api.utils import dict_merge
+from scheduler import KubeException
 
 logger = logging.getLogger(__name__)
 
 
-class AlreadyExists(EnvironmentError):
-    pass
+class DeisException(APIException):
+    status_code = 400
+
+
+class AlreadyExists(APIException):
+    status_code = 409
+
+
+class ServiceUnavailable(APIException):
+    status_code = 503
+    default_detail = 'Service temporarily unavailable, try again later.'
 
 
 def log_event(app, msg, level=logging.INFO):
@@ -57,8 +68,12 @@ def _scheduler(self):
         return mod.SchedulerClient()
 
     def _fetch_service_config(self, app):
-        # Get the service from k8s to attach the domain correctly
-        svc = self._scheduler._get_service(app, app).json()
+        try:
+            # Get the service from k8s to attach the domain correctly
+            svc = self._scheduler._get_service(app, app).json()
+        except KubeException as e:
+            raise ServiceUnavailable(str(e)) from e
+
         # Get minimum structure going if it is missing on the service
         if 'metadata' not in svc or 'annotations' not in svc['metadata']:
             default = {'metadata': {'annotations': {}}}
@@ -90,8 +105,11 @@ def _save_service_config(self, app, component, data):
         data = {"%s%s" % (component, key): value for key, value in list(data.items())}
         svc['metadata']['annotations'].update(morph.flatten(data))
 
-        # Update the k8s service for the application with new domain information
-        self._scheduler._update_service(app, app, svc)
+        # Update the k8s service for the application with new service information
+        try:
+            self._scheduler._update_service(app, app, svc)
+        except KubeException as e:
+            raise ServiceUnavailable(str(e)) from e
 
 
 class UuidAuditedModel(AuditedModel):

rootfs/api/models/app.py

@@ -11,11 +11,12 @@
 
 from django.conf import settings
 from django.db import models
-from django.core.exceptions import ValidationError
+from rest_framework.exceptions import ValidationError, NotFound
 from jsonfield import JSONField
 
 from deis import __version__ as deis_version
-from api.models import UuidAuditedModel, log_event, AlreadyExists
+from api.models import UuidAuditedModel, log_event, AlreadyExists, \
+    DeisException, ServiceUnavailable
 
 from api.utils import generate_app_name, app_build_type
 from api.models.release import Release
@@ -43,7 +44,7 @@ def validate_app_structure(value):
         if any(int(v) < 0 for v in value.values()):
             raise ValueError("Must be greater than or equal to zero")
     except ValueError as err:
-        raise ValidationError(err)
+        raise ValidationError(str(err))
 
 
 def validate_reserved_names(value):
@@ -152,7 +153,10 @@ def create(self, *args, **kwargs):
             )
 
         # create required minimum resources in k8s for the application
-        self._scheduler.create(self.id)
+        try:
+            self._scheduler.create(self.id)
+        except KubeException as e:
+            raise ServiceUnavailable(str(e)) from e
 
         # Attach the platform specific application sub domain to the k8s service
         # Only attach it on first release in case a customer has remove the app domain
@@ -164,8 +168,8 @@ def delete(self, *args, **kwargs):
         try:
             # attempt to remove application from kubernetes
             self._scheduler.destroy(self.id)
-        except KubeException:
-            pass
+        except KubeException as e:
+            raise ServiceUnavailable(str(e)) from e
 
         self._clean_app_logs()
         return super(App, self).delete(*args, **kwargs)
@@ -213,7 +217,7 @@ def restart(self, **kwargs):  # noqa
             while True:
                 # timed out
                 if elapsed >= timeout:
-                    raise KubeException('timeout - 5 minutes have passed and pods are not up')
+                    raise DeisException('timeout - 5 minutes have passed and pods are not up')
 
                 # restarting a single pod behaves differently, fetch the *newest* pod
                 # and hope it is the right one. Comes back sorted
@@ -234,7 +238,6 @@ def restart(self, **kwargs):  # noqa
 
                 elapsed += 5
                 time.sleep(5)
-
         except Exception as e:
             err = "warning, some pods failed to start:\n{}".format(str(e))
             log_event(self, err, logging.WARNING)
@@ -261,18 +264,26 @@ def scale(self, user, structure):  # noqa
         self.create()
 
         if self.release_set.latest().build is None:
-            raise EnvironmentError('No build associated with this release')
+            raise DeisException('No build associated with this release')
 
         release = self.release_set.latest()
 
+        # Validate structure
+        try:
+            for target, count in structure.copy().items():
+                structure[target] = int(count)
+            validate_app_structure(structure)
+        except (TypeError, ValueError) as e:
+            raise DeisException('Invalid scaling format: {}'.format(e))
+
         # test for available process types
         available_process_types = release.build.procfile or {}
         for container_type in structure:
             if container_type == 'cmd':
                 continue  # allow docker cmd types in case we don't have the image source
 
             if container_type not in available_process_types:
-                raise EnvironmentError(
+                raise DeisException(
                     'Container type {} does not exist in application'.format(container_type))
 
         # merge current structure and the new items together
@@ -323,16 +334,15 @@ def _scale_pods(self, scale_types):
                     command=command,
                     **kwargs
                 )
-
             except Exception as e:
                 err = '{} (scale): {}'.format(self._get_job_id(scale_type), e)
                 log_event(self, err, logging.ERROR)
-                raise
+                raise ServiceUnavailable(e) from e
 
     def deploy(self, release):
         """Deploy a new release to this application"""
         if release.build is None:
-            raise EnvironmentError('No build associated with this release')
+            raise DeisException('No build associated with this release')
 
         # use create to make sure minimum resources are created
         self.create()
@@ -386,7 +396,7 @@ def deploy(self, release):
             except Exception as e:
                 err = '{} (app::deploy): {}'.format(self._get_job_id(scale_type), e)
                 log_event(self, err, logging.ERROR)
-                raise
+                raise ServiceUnavailable(err) from e
 
         # cleanup old releases from kubernetes
         release.cleanup_old()
@@ -508,19 +518,20 @@ def logs(self, log_lines=str(settings.LOG_LINES)):
             r = requests.get(url)
         # Handle HTTP request errors
         except requests.exceptions.RequestException as e:
-            logger.error("Error accessing deis-logger using url '{}': {}".format(url, e))
-            raise e
+            msg = "Error accessing deis-logger using url '{}': {}".format(url, e)
+            logger.error(msg)
+            raise ServiceUnavailable(msg) from e
 
         # Handle logs empty or not found
         if r.status_code == 204 or r.status_code == 404:
             logger.info("GET {} returned a {} status code".format(url, r.status_code))
-            raise EnvironmentError('Could not locate logs')
+            raise NotFound('Could not locate logs')
 
         # Handle unanticipated status codes
         if r.status_code != 200:
             logger.error("Error accessing deis-logger: GET {} returned a {} status code"
                          .format(url, r.status_code))
-            raise EnvironmentError('Error accessing deis-logger')
+            raise ServiceUnavailable('Error accessing deis-logger')
 
         # cast content to string since it comes as bytes via the requests object
         return str(r.content)
@@ -532,7 +543,7 @@ def pod_name(size=5, chars=string.ascii_lowercase + string.digits):
         """Run a one-off command in an ephemeral app container."""
         release = self.release_set.latest()
         if release.build is None:
-            raise EnvironmentError('No build associated with this release to run this command')
+            raise DeisException('No build associated with this release to run this command')
 
         # TODO: add support for interactive shell
         # SECURITY: shell-escape user input
@@ -576,7 +587,7 @@ def pod_name(size=5, chars=string.ascii_lowercase + string.digits):
         except Exception as e:
             err = '{} (run): {}'.format(name, e)
             log_event(self, err, logging.ERROR)
-            raise
+            raise ServiceUnavailable(str(e)) from e
 
     def list_pods(self, *args, **kwargs):
         """Used to list basic information about pods running for a given application"""
@@ -627,7 +638,7 @@ def list_pods(self, *args, **kwargs):
         except Exception as e:
             err = '(list pods): {}'.format(e)
             log_event(self, err, logging.ERROR)
-            raise
+            raise ServiceUnavailable(err) from e
 
     def _scheduler_filter(self, **kwargs):
         labels = {'app': self.id}

rootfs/api/models/build.py

@@ -2,7 +2,7 @@
 from django.db import models
 from jsonfield import JSONField
 
-from api.models import UuidAuditedModel
+from api.models import UuidAuditedModel, DeisException
 
 import logging
 logger = logging.getLogger(__name__)
@@ -43,10 +43,11 @@ def create(self, user, *args, **kwargs):
         try:
             self.app.deploy(new_release)
             return new_release
-        except Exception:
+        except Exception as e:
             if 'new_release' in locals():
                 new_release.delete()
-            raise
+
+            raise DeisException(str(e)) from e
 
     def save(self, **kwargs):
         try:

rootfs/api/models/certificate.py

@@ -8,13 +8,14 @@
 from django.shortcuts import get_object_or_404
 from django.db import models
 from django.conf import settings
-from django.core.exceptions import ValidationError, SuspiciousOperation
+from django.core.exceptions import SuspiciousOperation
 from django.contrib.postgres.fields import ArrayField
+from rest_framework.exceptions import ValidationError
 
-from api.models import AuditedModel, validate_label, AlreadyExists
+from api.models import AuditedModel, validate_label, AlreadyExists, ServiceUnavailable
 from api.models.domain import Domain
 
-from scheduler import KubeHTTPException
+from scheduler import KubeException
 
 import logging
 logger = logging.getLogger(__name__)
@@ -179,15 +180,15 @@ def attach_in_kubernetes(self, domain):
             }
 
             secret = self._scheduler._get_secret(app, name).json()['data']
-        except KubeHTTPException:
+        except KubeException:
             self._scheduler._create_secret(app, name, data)
         else:
             # update cert secret to the TLS Ingress format if required
             if secret != data:
                 try:
                     self._scheduler._update_secret(app, name, data)
-                except KubeHTTPException:
-                    raise
+                except KubeException as e:
+                    raise ServiceUnavailable(str(e)) from e
 
         # get config for the service
         config = self._load_service_config(app, 'router')
@@ -220,9 +221,8 @@ def detach(self, *args, **kwargs):
                 # We raise an exception when a secret doesn't exist
                 self._scheduler._get_secret(app, name)
                 self._scheduler._delete_secret(app, name)
-            except KubeHTTPException as e:
-                logger.critical(e)
-                raise EnvironmentError("Could not delete certificate secret {} for application {}".format(name, app))  # noqa
+            except KubeException as e:
+                raise ServiceUnavailable("Could not delete certificate secret {} for application {}".format(name, app)) from e  # noqa
 
         # get config for the service
         config = self._load_service_config(app, 'router')

rootfs/api/models/config.py

@@ -2,7 +2,7 @@
 from django.db import models
 from jsonfield import JSONField
 
-from api.models import UuidAuditedModel
+from api.models import UuidAuditedModel, DeisException
 
 
 class Config(UuidAuditedModel):
@@ -107,7 +107,7 @@ def set_tags(self, previous_config):
             new = set(labels) - set(old)
             message += ' - Addition of {} is the cause'.format(', '.join(new))
 
-        raise EnvironmentError(message)
+        raise DeisException(message)
 
     def save(self, **kwargs):
         """merge the old config with the new"""

rootfs/api/models/key.py

@@ -2,7 +2,7 @@
 
 from django.conf import settings
 from django.db import models
-from django.core.exceptions import ValidationError
+from rest_framework.exceptions import ValidationError
 
 from api.models import UuidAuditedModel
 from api.utils import fingerprint
@@ -13,7 +13,7 @@ def validate_base64(value):
     try:
         base64.b64decode(value.split()[1])
     except Exception as e:
-        raise ValidationError(e)
+        raise ValidationError(str(e))
 
 
 class Key(UuidAuditedModel):