Update dependencies (FastAPI, uvicorn, etc.) (ExpDev07#337)

* update `generate_reqs` invoke task for latest pipenv
* fastapi 0.61 -> 0.63
* uvicorn 0.11.8 -> 0.13.4
* sentry, scout updates, etc
* update requirements test
* update Sources enum
* linting fix (invalid-name)
* use Sources enum instead of string
* skip test_requirements if not python3.8

Author: simran7s

app/data/__init__.py

@@ -3,12 +3,24 @@
 from ..services.location.jhu import JhuLocationService
 from ..services.location.nyt import NYTLocationService
 
-# Mapping of services to data-sources.
-DATA_SOURCES = {
-    "jhu": JhuLocationService(),
-    "csbs": CSBSLocationService(),
-    "nyt": NYTLocationService(),
-}
+
+class DataSourceSingleton:
+    _instance = None
+
+    def __new__(self):
+        # creates new DataSourceSingleton instance iff one does not exist.
+        # Then returns the new/existing instance
+        if not DataSourceSingleton._instance:
+            DataSourceSingleton._instance = super(
+                DataSourceSingleton, self).__new__(self)
+
+            # Mapping of services to data-sources.
+            self._DATA_SOURCES = {
+                "jhu": JhuLocationService(),
+                "csbs": CSBSLocationService(),
+                "nyt": NYTLocationService(),
+            }
+        return DataSourceSingleton._instance
 
 
 def data_source(source):
@@ -18,4 +30,6 @@ def data_source(source):
     :returns: The service.
     :rtype: LocationService
     """
-    return DATA_SOURCES.get(source.lower())
+
+    storedSources = DataSourceSingleton()
+    return storedSources._DATA_SOURCES.get(source.lower())

app/routers/v2.py

@@ -3,7 +3,7 @@
 
 from fastapi import APIRouter, HTTPException, Request
 
-from ..data import DATA_SOURCES
+from ..data import DataSourceSingleton
 from ..models import LatestResponse, LocationResponse, LocationsResponse
 
 V2 = APIRouter()
@@ -107,4 +107,5 @@ async def sources():
     """
     Retrieves a list of data-sources that are availble to use.
     """
-    return {"sources": list(DATA_SOURCES.keys())}
+    storedSources = DataSourceSingleton()
+    return {"sources": list(storedSources._DATA_SOURCES.keys())}