Fix map_to_s3 configuration

cdn_lambda/functions/map_to_s3/map_to_s3.json

@@ -0,0 +1,6 @@
+{
+  "table": {
+    "name": "exodus",
+    "region": "us-east-1"
+  }
+}

cdn_lambda/functions/map_to_s3/map_to_s3.py

@@ -0,0 +1,90 @@
+import json
+import logging
+from datetime import datetime, timezone
+
+import boto3
+
+LOG = logging.getLogger("map-to-s3-lambda")
+
+
+class LambdaClient(object):
+    def __init__(self, conf_file="map_to_s3.json"):
+        self._conf_file = conf_file
+
+        self._conf = None
+        self._db_client = None
+
+    @property
+    def conf(self):
+        if not self._conf:
+            with open(self._conf_file, "r") as json_file:
+                self._conf = json.load(json_file)
+
+        return self._conf
+
+    @property
+    def db_client(self):
+        if not self._db_client:
+            self._db_client = boto3.client(
+                "dynamodb", region_name=self.conf["table"]["region"]
+            )
+
+        return self._db_client
+
+    def handler(self, event, context):
+        # pylint: disable=unused-argument
+
+        request = event["Records"][0]["cf"]["request"]
+
+        LOG.info(
+            "Querying '%s' table for '%s'...",
+            self.conf["table"]["name"],
+            request["uri"],
+        )
+
+        query_result = self.db_client.query(
+            TableName=self.conf["table"]["name"],
+            Limit=1,
+            ScanIndexForward=False,
+            KeyConditionExpression="web_uri = :u and from_date <= :d",
+            ExpressionAttributeValues={
+                ":u": {"S": request["uri"]},
+                ":d": {
+                    "S": str(
+                        datetime.now(timezone.utc).isoformat(
+                            timespec="milliseconds"
+                        )
+                    )
+                },
+            },
+        )
+
+        if query_result["Items"]:
+            LOG.info("Item found for '%s'", request["uri"])
+
+            try:
+                # Update request uri to point to S3 object key
+                request["uri"] = (
+                    "/" + query_result["Items"][0]["object_key"]["S"]
+                )
+
+                return request
+            except Exception as err:
+                LOG.exception(
+                    "Exception occurred while processing %s",
+                    json.dumps(query_result["Items"][0]),
+                )
+
+                raise err
+        else:
+            LOG.info("No item found for '%s'", request["uri"])
+
+            # Report 404 to prevent attempts on S3
+            return {
+                "status": "404",
+                "statusDescription": "Not Found",
+            }
+
+
+# Make handler available at module level
+lambda_handler = LambdaClient().handler

docs/functions/map_to_s3.rst

@@ -14,24 +14,22 @@ Deployment
 ----------
 
 This function may be deployed like any other AWS Lambda function using the
-following event and environment variables.
+following event and configuration file.
 
 Event
 ^^^^^
 The event for this function must be a CloudFront distribution origin-request to
 an S3 bucket.
 
-Environment Variables
-^^^^^^^^^^^^^^^^^^^^^
-- DB_TABLE_NAME
-    (Required)
+Configuration
+^^^^^^^^^^^^^
+The map_to_s3 function must be deployed with the map_to_s3.json configuration
+file.
 
-    The name of the DynamoDB table from which to derive mapping.
-- DB_TABLE_REGION
-    (Optional)
+- table
+    The DynamoDB table from which to derive path to key mapping.
 
-    The AWS region in which the table resides.
-    If omitted, the region used is that of the function.
-
-`AWS Lambda Environment Variables
-<https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html>`_
+    - name
+        The name of the DynamoDB table.
+    - region
+        The AWS region in which the table resides.

tests/functions/test_map_to_s3.py

@@ -1,15 +1,15 @@
-from cdn_lambda.functions.map_to_s3 import lambda_handler
-import os
+from cdn_lambda.functions.map_to_s3.map_to_s3 import LambdaClient
 import pytest
 import mock
 import json
 
 TEST_PATH = "www.example.com/content/file.ext"
 MOCKED_DT = "2020-02-17T15:38:05.864+00:00"
+CONF_PATH = "cdn_lambda/functions/map_to_s3/map_to_s3.json"
 
 
 @mock.patch("boto3.client")
-@mock.patch("cdn_lambda.functions.map_to_s3.datetime")
+@mock.patch("cdn_lambda.functions.map_to_s3.map_to_s3.datetime")
 def test_map_to_s3(mocked_datetime, mocked_boto3_client):
     mocked_datetime.now().isoformat.return_value = MOCKED_DT
     mocked_boto3_client().query.return_value = {
@@ -22,32 +22,28 @@ def test_map_to_s3(mocked_datetime, mocked_boto3_client):
         ]
     }
 
-    env_vars = {"DB_TABLE_NAME": "test_table", "DB_TABLE_REGION": "us-east-1"}
     event = {"Records": [{"cf": {"request": {"uri": TEST_PATH}}}]}
 
-    with mock.patch.dict(os.environ, env_vars):
-        request = lambda_handler(event, context=None)
+    request = LambdaClient(conf_file=CONF_PATH).handler(event, context=None)
 
-    assert request == {"uri": "e4a3f2sum"}
+    assert request == {"uri": "/e4a3f2sum"}
 
 
 @mock.patch("boto3.client")
-@mock.patch("cdn_lambda.functions.map_to_s3.datetime")
+@mock.patch("cdn_lambda.functions.map_to_s3.map_to_s3.datetime")
 def test_map_to_s3_no_item(mocked_datetime, mocked_boto3_client):
     mocked_datetime.now().isoformat.return_value = MOCKED_DT
     mocked_boto3_client().query.return_value = {"Items": []}
 
-    env_vars = {"DB_TABLE_NAME": "test_table", "DB_TABLE_REGION": "us-east-1"}
     event = {"Records": [{"cf": {"request": {"uri": TEST_PATH}}}]}
 
-    with mock.patch.dict(os.environ, env_vars):
-        request = lambda_handler(event, context=None)
+    request = LambdaClient(conf_file=CONF_PATH).handler(event, context=None)
 
     assert request == {"status": "404", "statusDescription": "Not Found"}
 
 
 @mock.patch("boto3.client")
-@mock.patch("cdn_lambda.functions.map_to_s3.datetime")
+@mock.patch("cdn_lambda.functions.map_to_s3.map_to_s3.datetime")
 def test_map_to_s3_invalid_item(mocked_datetime, mocked_boto3_client, caplog):
     mocked_datetime.now().isoformat.return_value = MOCKED_DT
     mocked_boto3_client().query.return_value = {
@@ -59,12 +55,10 @@ def test_map_to_s3_invalid_item(mocked_datetime, mocked_boto3_client, caplog):
         ]
     }
 
-    env_vars = {"DB_TABLE_NAME": "test_table", "DB_TABLE_REGION": "us-east-1"}
     event = {"Records": [{"cf": {"request": {"uri": TEST_PATH}}}]}
 
-    with mock.patch.dict(os.environ, env_vars):
-        with pytest.raises(KeyError):
-            lambda_handler(event, context=None)
+    with pytest.raises(KeyError):
+        LambdaClient(conf_file=CONF_PATH).handler(event, context=None)
 
     assert (
         "Exception occurred while processing %s"