Cloudwatch get metric data return by period (#3626)

* Cloudwatch get metric data return by period

- addresses https://github.com/localstack/localstack/issues/3493

* fix lint issues

* remove unused import

* added test cases for min max and average

moto/cloudwatch/models.py

@@ -388,39 +388,62 @@ class CloudWatchBackend(BaseBackend):
                 )
             )
 
-    def get_metric_data(self, queries, start_time, end_time):
+    def get_metric_data(
+        self, queries, start_time, end_time, scan_by="TimestampAscending"
+    ):
+
         period_data = [
             md for md in self.metric_data if start_time <= md.timestamp <= end_time
         ]
+
         results = []
         for query in queries:
+            period_start_time = start_time
             query_ns = query["metric_stat._metric._namespace"]
             query_name = query["metric_stat._metric._metric_name"]
-            query_data = [
-                md
-                for md in period_data
-                if md.namespace == query_ns and md.name == query_name
-            ]
-            metric_values = [m.value for m in query_data]
+            delta = timedelta(seconds=int(query["metric_stat._period"]))
             result_vals = []
+            timestamps = []
             stat = query["metric_stat._stat"]
-            if len(metric_values) > 0:
-                if stat == "Average":
-                    result_vals.append(sum(metric_values) / len(metric_values))
-                elif stat == "Minimum":
-                    result_vals.append(min(metric_values))
-                elif stat == "Maximum":
-                    result_vals.append(max(metric_values))
-                elif stat == "Sum":
-                    result_vals.append(sum(metric_values))
+            while period_start_time <= end_time:
+                period_end_time = period_start_time + delta
+                period_md = [
+                    period_md
+                    for period_md in period_data
+                    if period_start_time <= period_md.timestamp < period_end_time
+                ]
 
+                query_period_data = [
+                    md
+                    for md in period_md
+                    if md.namespace == query_ns and md.name == query_name
+                ]
+
+                metric_values = [m.value for m in query_period_data]
+
+                if len(metric_values) > 0:
+                    if stat == "Average":
+                        result_vals.append(sum(metric_values) / len(metric_values))
+                    elif stat == "Minimum":
+                        result_vals.append(min(metric_values))
+                    elif stat == "Maximum":
+                        result_vals.append(max(metric_values))
+                    elif stat == "Sum":
+                        result_vals.append(sum(metric_values))
+                    timestamps.append(
+                        iso_8601_datetime_without_milliseconds(period_start_time)
+                    )
+                period_start_time += delta
+            if scan_by == "TimestampDescending" and len(timestamps) > 0:
+                timestamps.reverse()
+                result_vals.reverse()
             label = query["metric_stat._metric._metric_name"] + " " + stat
             results.append(
                 {
                     "id": query["id"],
                     "label": label,
                     "vals": result_vals,
-                    "timestamps": [datetime.now() for _ in result_vals],
+                    "timestamps": timestamps,
                 }
             )
         return results

moto/cloudwatch/responses.py

@@ -128,9 +128,11 @@ class CloudWatchResponse(BaseResponse):
     def get_metric_data(self):
         start = dtparse(self._get_param("StartTime"))
         end = dtparse(self._get_param("EndTime"))
+        scan_by = self._get_param("ScanBy")
+
         queries = self._get_list_prefix("MetricDataQueries.member")
         results = self.cloudwatch_backend.get_metric_data(
-            start_time=start, end_time=end, queries=queries
+            start_time=start, end_time=end, queries=queries, scan_by=scan_by
         )
 
         template = self.response_template(GET_METRIC_DATA_TEMPLATE)

tests/test_cloudwatch/test_cloudwatch_boto3.py

@@ -678,6 +678,7 @@ def test_get_metric_data_partially_within_timeframe():
             }
         ],
     )
+
     cloudwatch.put_metric_data(
         Namespace=namespace1,
         MetricData=[
@@ -686,31 +687,89 @@ def test_get_metric_data_partially_within_timeframe():
                 "Value": 50,
                 "Unit": "Seconds",
                 "Timestamp": last_week,
-            }
-        ],
-    )
-    # get_metric_data
-    response = cloudwatch.get_metric_data(
-        MetricDataQueries=[
+            },
             {
-                "Id": "result",
-                "MetricStat": {
-                    "Metric": {"Namespace": namespace1, "MetricName": "metric1"},
-                    "Period": 60,
-                    "Stat": "Sum",
-                },
-            }
+                "MetricName": "metric1",
+                "Value": 10,
+                "Unit": "Seconds",
+                "Timestamp": last_week + timedelta(seconds=10),
+            },
+            {
+                "MetricName": "metric1",
+                "Value": 20,
+                "Unit": "Seconds",
+                "Timestamp": last_week + timedelta(seconds=15),
+            },
+            {
+                "MetricName": "metric1",
+                "Value": 40,
+                "Unit": "Seconds",
+                "Timestamp": last_week + timedelta(seconds=30),
+            },
         ],
-        StartTime=yesterday - timedelta(seconds=60),
-        EndTime=utc_now + timedelta(seconds=60),
     )
-    #
+
+    # data for average, min, max
+
+    def get_data(start, end, stat="Sum", scanBy="TimestampAscending"):
+        # get_metric_data
+        response = cloudwatch.get_metric_data(
+            MetricDataQueries=[
+                {
+                    "Id": "result",
+                    "MetricStat": {
+                        "Metric": {"Namespace": namespace1, "MetricName": "metric1"},
+                        "Period": 60,
+                        "Stat": stat,
+                    },
+                }
+            ],
+            StartTime=start,
+            EndTime=end,
+            ScanBy=scanBy,
+        )
+        return response
+
+    response = get_data(
+        start=yesterday - timedelta(seconds=60), end=utc_now + timedelta(seconds=60),
+    )
+
     # Assert Last week's data is not returned
     len(response["MetricDataResults"]).should.equal(1)
     sum_ = response["MetricDataResults"][0]
     sum_["Label"].should.equal("metric1 Sum")
     sum_["StatusCode"].should.equal("Complete")
-    sum_["Values"].should.equal([30.0])
+    sum_["Values"].should.equal([20.0, 10.0])
+    response = get_data(
+        start=yesterday - timedelta(seconds=60),
+        end=utc_now + timedelta(seconds=60),
+        scanBy="TimestampDescending",
+    )
+    response["MetricDataResults"][0]["Values"].should.equal([10.0, 20.0])
+
+    response = get_data(
+        start=last_week - timedelta(seconds=1),
+        end=utc_now + timedelta(seconds=60),
+        stat="Average",
+    )
+    # assert average
+    response["MetricDataResults"][0]["Values"].should.equal([30.0, 20.0, 10.0])
+
+    response = get_data(
+        start=last_week - timedelta(seconds=1),
+        end=utc_now + timedelta(seconds=60),
+        stat="Maximum",
+    )
+    # assert maximum
+    response["MetricDataResults"][0]["Values"].should.equal([50.0, 20.0, 10.0])
+
+    response = get_data(
+        start=last_week - timedelta(seconds=1),
+        end=utc_now + timedelta(seconds=60),
+        stat="Minimum",
+    )
+    # assert minimum
+    response["MetricDataResults"][0]["Values"].should.equal([10.0, 20.0, 10.0])
 
 
 @mock_cloudwatch