aws-ce-grafana-backend: fix from/to edge cases

helm-charts/aws-ce-grafana-backend/mounted-files/webserver.py

@@ -1,5 +1,5 @@
 import logging
-from datetime import date, datetime, timedelta, timezone
+from datetime import datetime, timedelta, timezone
 
 from flask import Flask, request
 
@@ -16,30 +16,41 @@
 
 def _parse_from_to_in_query_params():
     """
-    Parse "from" and "to" query parameters, expected to arrive as YYYY-MM-DD
-    strings.
-
-    # FIXME: Avoid...
-    #        botocore.exceptions.ClientError: An error occurred (ValidationException) when calling the GetCostAndUsage operation: end date past the beginning of next month
+    Parse "from" and "to" query parameters, expected to be passed as YYYY-MM-DD
+    formatted strings or including time as well.
 
     - "to" defaults to current date (UTC)
     - "from" defaults to 30 days before what to is set to
+
+    Note that Python 3.11 is required to parse a datetime like
+    2024-07-27T15:50:18.231Z with a Z in the end, and that Grafana's
+    `${__from:date}` variable is UTC based, but as soon as its adjusted with a
+    custom format, it no longer is UTC based. Due to that, we need to be able to
+    parse the full datetime string.
     """
+    now_date = datetime.now(timezone.utc).date()
     if request.args.get("to"):
-        to_dt = date.fromisoformat(request.args["to"])
+        to_date = datetime.fromisoformat(request.args["to"]).date()
     else:
-        to_dt = datetime.now(timezone.utc).date()
+        to_date = now_date
     if request.args.get("from"):
-        from_dt = date.fromisoformat(request.args["from"])
+        from_date = datetime.fromisoformat(request.args["from"]).date()
     else:
-        from_dt = to_dt - timedelta(days=30)
-
-    # the end date gets excluded, so add one day to get it included
-    to_dt += timedelta(days=1)
+        from_date = to_date - timedelta(days=30)
+
+    # the to_date isn't included when declaring start/end dates against the AWS
+    # CE API, so we try to add one day to it to make it inclusive
+    to_date = to_date + timedelta(days=1)
+    # prevent "end date past the beginning of next month" errors
+    if to_date > now_date:
+        to_date = now_date
+    # prevent "Start date (and hour) should be before end date (and hour)"
+    if from_date >= now_date:
+        from_date = to_date - timedelta(days=1)
 
     # format back to YYYY-MM-DD strings
-    from_date = from_dt.strftime("%Y-%m-%d")
-    to_date = to_dt.strftime("%Y-%m-%d")
+    from_date = from_date.strftime("%Y-%m-%d")
+    to_date = to_date.strftime("%Y-%m-%d")
 
     return from_date, to_date