Much of the way towards complete DynamoDB Streams implementation

moto/dynamodbstreams/__init__.py

@@ -0,0 +1,6 @@
+from __future__ import unicode_literals
+from .models import dynamodbstreams_backends
+from ..core.models import base_decorator
+
+dynamodbstreams_backend = dynamodbstreams_backends['us-east-1']
+mock_dynamodbstreams = base_decorator(dynamodbstreams_backends)

moto/dynamodbstreams/models.py

@@ -0,0 +1,99 @@
+from __future__ import unicode_literals
+
+import os
+import json
+import boto3
+import base64
+import datetime
+
+from moto.core import BaseBackend, BaseModel
+from moto.dynamodb2.models import dynamodb_backends
+
+
+class ShardIterator(BaseModel):
+    def __init__(self, stream_shard, shard_iterator_type, sequence_number=None):
+        self.id = base64.b64encode(os.urandom(472)).decode('utf-8')
+        self.stream_shard = stream_shard
+        self.shard_iterator_type = shard_iterator_type
+        if shard_iterator_type == 'TRIM_HORIZON':
+            self.sequence_number = stream_shard.starting_sequence_number
+        elif shard_iterator_type == 'LATEST':
+            self.sequence_number = stream_shard.starting_sequence_number + len(stream_shard.items)
+        elif shard_iterator_type == 'AT_SEQUENCE_NUMBER':
+            self.sequence_number = sequence_number
+        elif shard_iterator_type == 'AFTER_SEQUENCE_NUMBER':
+            self.sequence_number = sequence_number + 1
+
+    def to_json(self):
+        return {
+            'ShardIterator': '{}/stream/{}|1|{}'.format(
+                self.stream_shard.table.table_arn,
+                self.stream_shard.table.latest_stream_label,
+                self.id)
+        }
+
+
+class DynamoDBStreamsBackend(BaseBackend):
+    def __init__(self, region):
+        self.region = region
+
+    def reset(self):
+        region = self.region
+        self.__dict__ = {}
+        self.__init__(region)
+        
+    @property
+    def dynamodb(self):
+        return dynamodb_backends[self.region]
+
+    def _get_table_from_arn(self, arn):
+        table_name = arn.split(':', 6)[5].split('/')[1]
+        return self.dynamodb.get_table(table_name)
+    
+    def describe_stream(self, arn):
+        table = self._get_table_from_arn(arn)
+        resp = {'StreamDescription': {
+            'StreamArn': arn,
+            'StreamLabel': table.latest_stream_label,
+            'StreamStatus': ('ENABLED' if table.latest_stream_label
+                             else 'DISABLED'),
+            'StreamViewType': table.stream_specification['StreamViewType'],
+            'CreationRequestDateTime': table.stream_shard.created_on.isoformat(),
+            'TableName': table.name,
+            'KeySchema': table.schema,
+            'Shards': ([table.stream_shard.to_json()] if table.stream_shard
+                       else [])
+        }}
+        
+        return json.dumps(resp)
+
+    def list_streams(self, table_name=None):
+        streams = []
+        for table in self.dynamodb.tables.values():
+            if table_name is not None and table.name != table_name:
+                continue
+            if table.latest_stream_label:
+                d = table.describe(base_key='Table')
+                streams.append({
+                    'StreamArn': d['Table']['LatestStreamArn'],
+                    'TableName': d['Table']['TableName'],
+                    'StreamLabel': d['Table']['LatestStreamLabel']
+                })
+                
+        return json.dumps({'Streams': streams})
+
+    def get_shard_iterator(self, arn, shard_id, shard_iterator_type, sequence_number=None):
+        table = self._get_table_from_arn(arn)
+        assert table.stream_shard.id == shard_id
+
+        shard_iterator = ShardIterator(table.stream_shard, shard_iterator_type,
+                                       sequence_number)
+        
+        return json.dumps(shard_iterator.to_json())
+
+    
+
+available_regions = boto3.session.Session().get_available_regions(
+    'dynamodbstreams')
+dynamodbstreams_backends = {region: DynamoDBStreamsBackend(region=region)
+                            for region in available_regions}

moto/dynamodbstreams/responses.py

@@ -0,0 +1,29 @@
+from __future__ import unicode_literals
+
+import json
+
+from moto.core.responses import BaseResponse
+
+from .models import dynamodbstreams_backends
+
+
+class DynamoDBStreamsHandler(BaseResponse):
+
+    @property
+    def backend(self):
+        return dynamodbstreams_backends[self.region]
+    
+    def describe_stream(self):
+        arn = self._get_param('StreamArn')
+        return self.backend.describe_stream(arn)
+
+    def list_streams(self):
+        table_name = self._get_param('TableName')
+        return self.backend.list_streams(table_name)
+
+    def get_shard_iterator(self):
+        arn = self._get_param('StreamArn')
+        shard_id = self._get_param('ShardId')
+        shard_iterator_type = self._get_param('ShardIteratorType')
+        return self.backend.get_shard_iterator(arn, shard_id,
+                                               shard_iterator_type)

moto/dynamodbstreams/urls.py

@@ -0,0 +1,10 @@
+from __future__ import unicode_literals
+from .responses import DynamoDBStreamsHandler
+
+url_bases = [
+    "https?://streams.dynamodb.(.+).amazonaws.com"
+]
+
+url_paths = {
+    "{0}/$": DynamoDBStreamsHandler.dispatch,
+}