Make MAX_PAYLOAD_SIZE configurable

pint_server/app.py

@@ -17,6 +17,7 @@
 
 import datetime
 import math
+import os
 import re
 from collections import namedtuple
 from dateutil.relativedelta import relativedelta
@@ -133,8 +134,10 @@
 SUPPORTED_CATEGORIES = ['images', 'servers']
 
 # NOTE: AWS lambda payload size cannot exceed 6MB. We are setting the
-# maximum payload size to 5.5MB to account for the HTTP protocol overheads
-MAX_PAYLOAD_SIZE = 5500000
+# default maximum payload size to 5.0MB to account for the HTTP protocol
+# overheads. However, this value can be overwritten with the
+# "MAX_PAYLOAD_SIZE" environment variable.
+DEFAULT_MAX_PAYLOAD_SIZE = 5000000
 
 # Provider specific deletion relative time deltas
 DELETION_RELATIVE_DELTA_MAP = {
@@ -678,18 +681,24 @@ def get_provider_servers(provider):
         servers = PROVIDER_SERVERS_MODEL_MAP[provider].query.all()
     return formatted_provider_servers(provider, servers)
 
+def get_max_payload_size():
+    if 'MAX_PAYLOAD_SIZE' in os.environ:
+        return int(os.environ.get('MAX_PAYLOAD_SIZE'))
+    else:
+        return DEFAULT_MAX_PAYLOAD_SIZE
 
 def trim_images_payload(images):
     payload_size = jsonify(images=images).content_length
+    max_payload_size = get_max_payload_size()
 
-    if payload_size >  MAX_PAYLOAD_SIZE:
+    if payload_size > max_payload_size:
         # NOTE: assuming the size of the entries are evenly distributed, we
         # determine the percentage of entries to trim from the end of the list,
         # as the list is sorted in decending order by publishedon date, by
         # calculating the percentage over the maximum payload size. Then
         # trim the same percentage off the list, rounding up to be safe.
         trim_size  = math.ceil(
-            ((payload_size - MAX_PAYLOAD_SIZE) / payload_size) * len(images))
+            ((payload_size - max_payload_size) / payload_size) * len(images))
         last_publishedon = images[-trim_size]['publishedon']
         images = images[:-trim_size]
 

pint_server/tests/unit/test_app.py

@@ -17,8 +17,10 @@
 
 import json
 import mock
+import os
 import pytest
 
+import pint_server
 from pint_server.tests.unit import mock_pint_data
 
 def test_root_request(client):
@@ -363,6 +365,15 @@ def test_get_provider_regions_image_deletiondate(client, provider, image, extens
                         assert expected_deletiondate == rv.json['deletiondate']
 
 
+def test_get_max_payload_size_default_value(client):
+    assert pint_server.app.get_max_payload_size() == pint_server.app.DEFAULT_MAX_PAYLOAD_SIZE
+
+
+@mock.patch.dict(os.environ, {"MAX_PAYLOAD_SIZE": "100"})
+def test_get_max_payload_size_default_override(client):
+    assert pint_server.app.get_max_payload_size() == 100
+
+
 def validate(rv, expected_status, extension):
     assert expected_status == rv.status_code
     assert rv.headers['Access-Control-Allow-Origin'] == '*'