Implement pluggability for tempest (exceptions)

First patch of three patches:
->1. exceptions
  2. config (+ module_utils.py)
  3. clients

The main intend is in moving currently existed single 'exceptions' module in
exceptions tree.
It allows separate exceptions by differencies:
- base
- main/common
- project-specific

It also allows to simplify search and using of exceptions, merge changes into
Tempest with minimized amount of merge conflicts.

Partially-implements: bp make-tempest-pluggable

Change-Id: I5c50affba0fce721583a6d56216e56c94ec3b188
diff --git a/tempest/exceptions.py b/tempest/exceptions.py
deleted file mode 100644
index ac88faa..0000000
--- a/tempest/exceptions.py
+++ /dev/null
@@ -1,187 +0,0 @@
-# Copyright 2012 OpenStack Foundation
-# All Rights Reserved.
-#
-#    Licensed under the Apache License, Version 2.0 (the "License"); you may
-#    not use this file except in compliance with the License. You may obtain
-#    a copy of the License at
-#
-#         http://www.apache.org/licenses/LICENSE-2.0
-#
-#    Unless required by applicable law or agreed to in writing, software
-#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-#    License for the specific language governing permissions and limitations
-#    under the License.
-
-import testtools
-
-
-class TempestException(Exception):
-    """
-    Base Tempest Exception
-
-    To correctly use this class, inherit from it and define
-    a 'message' property. That message will get printf'd
-    with the keyword arguments provided to the constructor.
-    """
-    message = "An unknown exception occurred"
-
-    def __init__(self, *args, **kwargs):
-        super(TempestException, self).__init__()
-        try:
-            self._error_string = self.message % kwargs
-        except Exception:
-            # at least get the core message out if something happened
-            self._error_string = self.message
-        if len(args) > 0:
-            # If there is a non-kwarg parameter, assume it's the error
-            # message or reason description and tack it on to the end
-            # of the exception message
-            # Convert all arguments into their string representations...
-            args = ["%s" % arg for arg in args]
-            self._error_string = (self._error_string +
-                                  "\nDetails: %s" % '\n'.join(args))
-
-    def __str__(self):
-        return self._error_string
-
-
-class InvalidConfiguration(TempestException):
-    message = "Invalid Configuration"
-
-
-class RestClientException(TempestException,
-                          testtools.TestCase.failureException):
-    pass
-
-
-class InvalidHttpSuccessCode(RestClientException):
-    message = "The success code is different than the expected one"
-
-
-class NotFound(RestClientException):
-    message = "Object not found"
-
-
-class Unauthorized(RestClientException):
-    message = 'Unauthorized'
-
-
-class InvalidServiceTag(RestClientException):
-    message = "Invalid service tag"
-
-
-class TimeoutException(TempestException):
-    message = "Request timed out"
-
-
-class BuildErrorException(TempestException):
-    message = "Server %(server_id)s failed to build and is in ERROR status"
-
-
-class ImageKilledException(TempestException):
-    message = "Image %(image_id)s 'killed' while waiting for '%(status)s'"
-
-
-class AddImageException(TempestException):
-    message = "Image %(image_id)s failed to become ACTIVE in the allotted time"
-
-
-class EC2RegisterImageException(TempestException):
-    message = ("Image %(image_id)s failed to become 'available' "
-               "in the allotted time")
-
-
-class VolumeBuildErrorException(TempestException):
-    message = "Volume %(volume_id)s failed to build and is in ERROR status"
-
-
-class SnapshotBuildErrorException(TempestException):
-    message = "Snapshot %(snapshot_id)s failed to build and is in ERROR status"
-
-
-class VolumeBackupException(TempestException):
-    message = "Volume backup %(backup_id)s failed and is in ERROR status"
-
-
-class StackBuildErrorException(TempestException):
-    message = ("Stack %(stack_identifier)s is in %(stack_status)s status "
-               "due to '%(stack_status_reason)s'")
-
-
-class BadRequest(RestClientException):
-    message = "Bad request"
-
-
-class UnprocessableEntity(RestClientException):
-    message = "Unprocessable entity"
-
-
-class AuthenticationFailure(RestClientException):
-    message = ("Authentication with user %(user)s and password "
-               "%(password)s failed auth using tenant %(tenant)s.")
-
-
-class EndpointNotFound(TempestException):
-    message = "Endpoint not found"
-
-
-class RateLimitExceeded(TempestException):
-    message = "Rate limit exceeded"
-
-
-class OverLimit(TempestException):
-    message = "Quota exceeded"
-
-
-class ServerFault(TempestException):
-    message = "Got server fault"
-
-
-class ImageFault(TempestException):
-    message = "Got image fault"
-
-
-class IdentityError(TempestException):
-    message = "Got identity error"
-
-
-class Conflict(RestClientException):
-    message = "An object with that identifier already exists"
-
-
-class SSHTimeout(TempestException):
-    message = ("Connection to the %(host)s via SSH timed out.\n"
-               "User: %(user)s, Password: %(password)s")
-
-
-class SSHExecCommandFailed(TempestException):
-    """Raised when remotely executed command returns nonzero status."""
-    message = ("Command '%(command)s', exit status: %(exit_status)d, "
-               "Error:\n%(strerror)s")
-
-
-class ServerUnreachable(TempestException):
-    message = "The server is not reachable via the configured network"
-
-
-class TearDownException(TempestException):
-    message = "%(num)d cleanUp operation failed"
-
-
-class RFCViolation(RestClientException):
-    message = "RFC Violation"
-
-
-class ResponseWithNonEmptyBody(RFCViolation):
-    message = ("RFC Violation! Response with %(status)d HTTP Status Code "
-               "MUST NOT have a body")
-
-
-class ResponseWithEntity(RFCViolation):
-    message = ("RFC Violation! Response with 205 HTTP Status Code "
-               "MUST NOT have an entity")
-
-
-class InvalidHTTPResponseBody(RestClientException):
-    message = "HTTP response body is invalid json or xml"
diff --git a/tempest/exceptions/README.rst b/tempest/exceptions/README.rst
new file mode 100644
index 0000000..dbe42b2
--- /dev/null
+++ b/tempest/exceptions/README.rst
@@ -0,0 +1,27 @@
+Tempest Field Guide to Exceptions
+=================================
+
+
+What are these exceptions?
+--------------------------
+
+These exceptions are used by Tempest for covering OpenStack specific exceptional
+cases.
+
+How to add new exceptions?
+--------------------------
+
+Each exception-template for inheritance purposes should be added into 'base'
+submodule.
+All other exceptions can be added in two ways:
+- in main module
+- in submodule
+But only in one of the ways. Need to make sure, that new exception is not
+present already.
+
+How to use exceptions?
+----------------------
+
+Any exceptions from this module or its submodules should be used in appropriate
+places to handle exceptional cases.
+Classes from 'base' module should be used only for inheritance.
diff --git a/tempest/exceptions/__init__.py b/tempest/exceptions/__init__.py
new file mode 100644
index 0000000..c95f94f
--- /dev/null
+++ b/tempest/exceptions/__init__.py
@@ -0,0 +1,148 @@
+# Copyright 2012 OpenStack Foundation
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from tempest.exceptions import base
+
+
+class InvalidConfiguration(base.TempestException):
+    message = "Invalid Configuration"
+
+
+class InvalidHttpSuccessCode(base.RestClientException):
+    message = "The success code is different than the expected one"
+
+
+class NotFound(base.RestClientException):
+    message = "Object not found"
+
+
+class Unauthorized(base.RestClientException):
+    message = 'Unauthorized'
+
+
+class InvalidServiceTag(base.RestClientException):
+    message = "Invalid service tag"
+
+
+class TimeoutException(base.TempestException):
+    message = "Request timed out"
+
+
+class BuildErrorException(base.TempestException):
+    message = "Server %(server_id)s failed to build and is in ERROR status"
+
+
+class ImageKilledException(base.TempestException):
+    message = "Image %(image_id)s 'killed' while waiting for '%(status)s'"
+
+
+class AddImageException(base.TempestException):
+    message = "Image %(image_id)s failed to become ACTIVE in the allotted time"
+
+
+class EC2RegisterImageException(base.TempestException):
+    message = ("Image %(image_id)s failed to become 'available' "
+               "in the allotted time")
+
+
+class VolumeBuildErrorException(base.TempestException):
+    message = "Volume %(volume_id)s failed to build and is in ERROR status"
+
+
+class SnapshotBuildErrorException(base.TempestException):
+    message = "Snapshot %(snapshot_id)s failed to build and is in ERROR status"
+
+
+class VolumeBackupException(base.TempestException):
+    message = "Volume backup %(backup_id)s failed and is in ERROR status"
+
+
+class StackBuildErrorException(base.TempestException):
+    message = ("Stack %(stack_identifier)s is in %(stack_status)s status "
+               "due to '%(stack_status_reason)s'")
+
+
+class BadRequest(base.RestClientException):
+    message = "Bad request"
+
+
+class UnprocessableEntity(base.RestClientException):
+    message = "Unprocessable entity"
+
+
+class AuthenticationFailure(base.RestClientException):
+    message = ("Authentication with user %(user)s and password "
+               "%(password)s failed auth using tenant %(tenant)s.")
+
+
+class EndpointNotFound(base.TempestException):
+    message = "Endpoint not found"
+
+
+class RateLimitExceeded(base.TempestException):
+    message = "Rate limit exceeded"
+
+
+class OverLimit(base.TempestException):
+    message = "Quota exceeded"
+
+
+class ServerFault(base.TempestException):
+    message = "Got server fault"
+
+
+class ImageFault(base.TempestException):
+    message = "Got image fault"
+
+
+class IdentityError(base.TempestException):
+    message = "Got identity error"
+
+
+class Conflict(base.RestClientException):
+    message = "An object with that identifier already exists"
+
+
+class SSHTimeout(base.TempestException):
+    message = ("Connection to the %(host)s via SSH timed out.\n"
+               "User: %(user)s, Password: %(password)s")
+
+
+class SSHExecCommandFailed(base.TempestException):
+    """Raised when remotely executed command returns nonzero status."""
+    message = ("Command '%(command)s', exit status: %(exit_status)d, "
+               "Error:\n%(strerror)s")
+
+
+class ServerUnreachable(base.TempestException):
+    message = "The server is not reachable via the configured network"
+
+
+class TearDownException(base.TempestException):
+    message = "%(num)d cleanUp operation failed"
+
+
+class ResponseWithNonEmptyBody(base.RFCViolation):
+    message = ("RFC Violation! Response with %(status)d HTTP Status Code "
+               "MUST NOT have a body")
+
+
+class ResponseWithEntity(base.RFCViolation):
+    message = ("RFC Violation! Response with 205 HTTP Status Code "
+               "MUST NOT have an entity")
+
+
+class InvalidHTTPResponseBody(base.RestClientException):
+    message = "HTTP response body is invalid json or xml"
diff --git a/tempest/exceptions/base.py b/tempest/exceptions/base.py
new file mode 100644
index 0000000..b8e470e
--- /dev/null
+++ b/tempest/exceptions/base.py
@@ -0,0 +1,55 @@
+# Copyright 2012 OpenStack Foundation
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import testtools
+
+
+class TempestException(Exception):
+    """
+    Base Tempest Exception
+
+    To correctly use this class, inherit from it and define
+    a 'message' property. That message will get printf'd
+    with the keyword arguments provided to the constructor.
+    """
+    message = "An unknown exception occurred"
+
+    def __init__(self, *args, **kwargs):
+        super(TempestException, self).__init__()
+        try:
+            self._error_string = self.message % kwargs
+        except Exception:
+            # at least get the core message out if something happened
+            self._error_string = self.message
+        if len(args) > 0:
+            # If there is a non-kwarg parameter, assume it's the error
+            # message or reason description and tack it on to the end
+            # of the exception message
+            # Convert all arguments into their string representations...
+            args = ["%s" % arg for arg in args]
+            self._error_string = (self._error_string +
+                                  "\nDetails: %s" % '\n'.join(args))
+
+    def __str__(self):
+        return self._error_string
+
+
+class RestClientException(TempestException,
+                          testtools.TestCase.failureException):
+    pass
+
+
+class RFCViolation(RestClientException):
+    message = "RFC Violation"