Reduce memory and s3 costs (#274)

Author: devinmatte

server/.chalice/config.json

@@ -4,7 +4,7 @@
   "api_gateway_endpoint_type": "REGIONAL",
   "minimum_compression_size": 1000,
   "lambda_timeout": 30,
-  "lambda_memory_size": 256,
+  "lambda_memory_size": 220,
   "layers": [
     "arn:aws:lambda:us-east-1:464622532012:layer:Datadog-Extension:91"
   ],

server/chalicelib/last_seen.py

@@ -27,18 +27,19 @@ def update_recent_sightings():
         all_vehicles = asyncio.run(mbta_api.vehicle_data_for_routes(ROUTES))
         new_vehicles = filter_new(all_vehicles)
 
-        for vehicle in new_vehicles:
-            line = get_line_for_route(vehicle["route"])
-            last_seen_times[line] = {
-                "car": vehicle["label"],
-                "time": now.isoformat(),
-            }
-        s3.upload(JSON_PATH, json.dumps(last_seen_times), compress=False)
+        if new_vehicles:
+            for vehicle in new_vehicles:
+                line = get_line_for_route(vehicle["route"])
+                last_seen_times[line] = {
+                    "car": vehicle["label"],
+                    "time": now.isoformat(),
+                }
+            s3.upload(JSON_PATH, json.dumps(last_seen_times), compress=False)
     except Exception as e:
         print("Couldn't write last seen times to s3: ", e)
 
 
 # Get the last time that a new train was seen on each line
 # This is the function that other modules use
 def get_recent_sightings_for_lines():
-    return json.loads(s3.download(JSON_PATH, "utf8"))
+    return json.loads(s3.download(JSON_PATH, "utf8", compressed=False))

server/chalicelib/mbta_api.py

@@ -123,7 +123,7 @@ async def trip_departure_predictions(trip_id: str, stop_id: str):
 # takes a list of route ids
 # uses getV3 to request real-time vehicle data for a given route id
 # returns list of all vehicles
-async def vehicle_data_for_routes(route_ids):
+async def vehicle_data_for_routes(route_ids: list[str]):
     route_ids = normalize_custom_route_ids(route_ids)
 
     try: