Started change to load endpoints from JSON.

This is just SNS/SES for the moment, for purposes of getting early review feedback. Still needs tests & docs, plus integration into the rest of the services.

1 files changed, 125 insertions, 0 deletions

diff --git a/boto/regioninfo.py b/boto/regioninfo.py
index 6e936b37..39853fa1 100644
--- a/boto/regioninfo.py
+++ b/boto/regioninfo.py
@@ -20,6 +20,131 @@
 # WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 # IN THE SOFTWARE.
+from __future__ import with_statement
+import os
+
+import boto
+from boto.compat import json
+from boto.exception import BotoClientError
+
+
+def load_endpoint_json(path):
+    """
+    Loads a given JSON file & returns it.
+
+    :param path: The path to the JSON file
+    :type path: string
+
+    :returns: The loaded data
+    """
+    with open(path, 'r') as endpoints_file:
+        return json.load(endpoints_file)
+
+
+def merge_endpoints(defaults, additions):
+    """
+    Given an existing set of endpoint data, this will deep-update it with
+    any similarly structured data in the additions.
+
+    :param defaults: The existing endpoints data
+    :type defaults: dict
+
+    :param defaults: The additional endpoints data
+    :type defaults: dict
+
+    :returns: The modified endpoints data
+    :rtype: dict
+    """
+    # We can't just do an ``defaults.update(...)`` here, as that could
+    # *overwrite* regions if present in both.
+    # We'll iterate instead, essentially doing a deeper merge.
+    for service, region_info in additions.items():
+        # Set the default, if not present, to an empty dict.
+        defaults.setdefault(service, {})
+        defaults[service].update(region_info)
+
+    return defaults
+
+
+def load_regions():
+    """
+    Actually load the region/endpoint information from the JSON files.
+
+    By default, this loads from the default included ``boto/endpoints.json``
+    file.
+
+    Users can override/extend this by supplying either a ``BOTO_ENDPOINTS``
+    environment variable or a ``endpoints_path`` config variable, either of
+    which should be an absolute path to the user's JSON file.
+
+    :returns: The endpoints data
+    :rtype: dict
+    """
+    # Load the defaults first.
+    endpoints = load_endpoint_json(boto.ENDPOINTS_PATH)
+    additional_path = None
+
+    # Try the ENV var. If not, check the config file.
+    if os.environ.get('BOTO_ENDPOINTS'):
+        additional_path = os.environ['BOTO_ENDPOINTS']
+    elif boto.config.get('boto', 'endpoints_path'):
+        additional_path = boto.config.get('boto', 'endpoints_path')
+
+    # If there's a file provided, we'll load it & additively merge it into
+    # the endpoints.
+    if additional_path:
+        additional = load_endpoint_json(additional_path)
+        endpoints = merge_endpoints(endpoints, additional)
+
+    return endpoints
+
+
+def get_regions(service_name, region_class=None, connection_cls=None):
+    """
+    Given a service name (like ``ec2``), returns a list of ``RegionInfo``
+    objects for that service.
+
+    This leverages the ``endpoints.json`` file (+ optional user overrides) to
+    configure/construct all the objects.
+
+    :param service_name: The name of the service to construct the ``RegionInfo``
+        objects for. Ex: ``ec2``, ``s3``, ``sns``, etc.
+    :type service_name: string
+
+    :param region_class: (Optional) The class to use when constructing. By
+        default, this is ``RegionInfo``.
+    :type region_class: class
+
+    :param connection_cls: (Optional) The connection class for the
+        ``RegionInfo`` object. Providing this allows the ``connect`` method on
+        the ``RegionInfo`` to work. Default is ``None`` (no connection).
+    :type connection_cls: class
+
+    :returns: A list of configured ``RegionInfo`` objects
+    :rtype: list
+    """
+    endpoints = load_regions()
+
+    if not service_name in endpoints:
+        raise BotoClientError(
+            "Service '%s' not found in endpoints." % service_name
+        )
+
+    if region_class is None:
+        region_class = RegionInfo
+
+    region_objs = []
+
+    for region_name, endpoint in endpoints.get(service_name, {}).items():
+        region_objs.append(
+            region_class(
+                name=region_name,
+                endpoint=endpoint,
+                connection_cls=connection_cls
+            )
+        )
+
+    return region_objs
 
 
 class RegionInfo(object):