Use stevedore Extensions for TOSCA definitions

This changes the TOSCA Parser extensions implementation to use a
stevedore Extensions namespace (toscaparser.extensions) to allow
TOSCA schema extensions to be loaded from other sources without
requiring them to be included in the tosca-parser repository.

Change-Id: Ia4d9430c398b2911043047d843419ff6edebfe3f

doc/source/usage.rst

@@ -16,3 +16,7 @@ entry point as::
     tosca-parser --template-file=toscaparser/tests/data/tosca_helloworld.yaml
 
 The value to the --template-file is required to be a relative or an absolute path.
+
+Custom template versions can be created and supported outside of TOSCA Parser
+using the toscaparser.extensions namespace.  See the NFV and MEC extensions
+for examples of how to define custom template definitions and versions.

requirements.txt

@@ -7,4 +7,5 @@ cliff!=2.9.0,>=2.8.0 # Apache-2.0
 PyYAML>=3.12 # MIT
 python-dateutil>=2.5.3 # BSD
 six>=1.10.0 # MIT
+stevedore>=1.20.0 # Apache-2.0
 requests>=2.14.2 # Apache-2.0

setup.cfg

@@ -27,6 +27,9 @@ packages =
 [entry_points]
 console_scripts =
     tosca-parser = toscaparser.shell:main
+toscaparser.extensions =
+    tosca_simple_profile_for_nfv_1_0_0 = toscaparser.extensions.nfv.tosca_simple_profile_for_nfv_1_0_0:NfvProfile_1_0_0
+    tosca_simple_profile_for_mec_1_0_0 = toscaparser.extensions.mec.tosca_simple_profile_for_mec_1_0_0:MecProfile_1_0_0
 
 [compile_catalog]
 directory = toscaparser/locale

toscaparser/extensions/exttools.py

@@ -16,6 +16,8 @@ import importlib
 import logging
 import os
 
+from stevedore import extension
+
 from toscaparser.common.exception import ToscaExtAttributeError
 from toscaparser.common.exception import ToscaExtImportError
 
@@ -32,41 +34,26 @@ class ExtTools(object):
         '''Dynamically load all the extensions .'''
         extensions = collections.OrderedDict()
 
-        # Use the absolute path of the class path
-        abs_path = os.path.dirname(os.path.abspath(__file__))
+        extns = extension.ExtensionManager(namespace='toscaparser.extensions',
+                                           invoke_on_load=True).extensions
 
-        extdirs = [e for e in os.listdir(abs_path) if
-                   not e.startswith('tests') and
-                   os.path.isdir(os.path.join(abs_path, e))]
+        for e in extns:
+            try:
+                extinfo = importlib.import_module(e.plugin.__module__)
+                base_path = os.path.dirname(extinfo.__file__)
+                version = e.plugin().VERSION
+                defs_file = base_path + '/' + e.plugin().DEFS_FILE
 
-        for e in extdirs:
-            log.info(e)
-            extpath = abs_path + '/' + e
-            # Grab all the extension files in the given path
-            ext_files = [f for f in os.listdir(extpath) if f.endswith('.py')
-                         and not f.startswith('__init__')]
+                # Sections is an optional attribute
+                sections = getattr(e.plugin(), 'SECTIONS', ())
 
-            # For each module, pick out the target translation class
-            for f in ext_files:
-                log.info(f)
-                ext_name = 'toscaparser/extensions/' + e + '/' + f.strip('.py')
-                ext_name = ext_name.replace('/', '.')
-                try:
-                    extinfo = importlib.import_module(ext_name)
-                    version = getattr(extinfo, 'VERSION')
-                    defs_file = extpath + '/' + getattr(extinfo, 'DEFS_FILE')
-
-                    # Sections is an optional attribute
-                    sections = getattr(extinfo, 'SECTIONS', ())
-
-                    extensions[version] = {'sections': sections,
-                                           'defs_file': defs_file}
-                except ImportError:
-                    raise ToscaExtImportError(ext_name=ext_name)
-                except AttributeError:
-                    attrs = ', '.join(REQUIRED_ATTRIBUTES)
-                    raise ToscaExtAttributeError(ext_name=ext_name,
-                                                 attrs=attrs)
+                extensions[version] = {'sections': sections,
+                                       'defs_file': defs_file}
+            except ImportError:
+                raise ToscaExtImportError(ext_name=e.name)
+            except AttributeError:
+                attrs = ', '.join(REQUIRED_ATTRIBUTES)
+                raise ToscaExtAttributeError(ext_name=e.name, attrs=attrs)
 
         return extensions
 

toscaparser/extensions/mec/tosca_simple_profile_for_mec_1_0_0.py

@@ -12,8 +12,10 @@
 
 # VERSION and DEFS_FILE are required for all extensions
 
-VERSION = 'tosca_simple_profile_for_mec_1_0_0'
 
-DEFS_FILE = "TOSCA_mec_definition_1_0_0.yaml"
+class MecProfile_1_0_0(object):
+    VERSION = 'tosca_simple_profile_for_mec_1_0_0'
 
-SECTIONS = ('metadata')
+    DEFS_FILE = "TOSCA_mec_definition_1_0_0.yaml"
+
+    SECTIONS = ('metadata')

toscaparser/extensions/nfv/tosca_simple_profile_for_nfv_1_0_0.py

@@ -9,11 +9,13 @@
 #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 #    License for the specific language governing permissions and limitations
 #    under the License.
-
+#
 # VERSION and DEFS_FILE are required for all extensions
 
-VERSION = 'tosca_simple_profile_for_nfv_1_0_0'
 
-DEFS_FILE = "TOSCA_nfv_definition_1_0_0.yaml"
+class NfvProfile_1_0_0(object):
+    VERSION = 'tosca_simple_profile_for_nfv_1_0_0'
 
-SECTIONS = ('metadata')
+    DEFS_FILE = 'TOSCA_nfv_definition_1_0_0.yaml'
+
+    SECTIONS = ('metadata')