Copying Stack tags to the Datadog monitor (#226)

Cloudformation supports tags at a stack level. They are normally passed on to all Cloudformation resources (some resources don't support that yet...). Datadog monitors got tags, too. With this change, the Cloudformation Stack tags are copied to the Datadog monitor. Additionally, the AWS autogenerated tags like stack name and logical id are also set. If a tag is already set explicitly at a monitor, the monitor value is being used.
Since Datadog uses a : to separate key and value, all : are replaced with _.

In order to maintain backwards compatibility, this feature is switched off by default. It can be enabled account-wide via the type configuration, the same way Datadog credentials are being set.

datadog-monitors-monitor-handler/datadog-monitors-monitor-configuration.json

@@ -2,6 +2,10 @@
     "properties": {
         "DatadogCredentials": {
             "$ref": "#/definitions/DatadogCredentials"
+        },
+        "TagResourceWithStackTags": {
+            "description": "Copy the Cloudformation Stack tags to the datadog monitor. It defaults to false to stay backwards compatible.",
+            "type": "boolean"
         }
     },
     "additionalProperties": false,

datadog-monitors-monitor-handler/datadog-monitors-monitor.json

@@ -5,6 +5,10 @@
     "properties": {
       "DatadogCredentials": {
         "$ref": "#/definitions/DatadogCredentials"
+      },
+      "TagResourceWithStackTags": {
+        "description": "Copy the Cloudformation Stack tags to the datadog monitor. It defaults to false to stay backwards compatible.",
+        "type": "boolean"
       }
     },
     "additionalProperties": false

datadog-monitors-monitor-handler/src/datadog_monitors_monitor/handlers.py

@@ -167,6 +167,7 @@ def update_handler(
         monitor.name = model.Name
     if model.Tags is not None:
         monitor.tags = model.Tags
+    _copy_stack_tags(monitor, request)
     if model.Priority is not None:
         monitor.priority = model.Priority
     if model.RestrictedRoles is not None:
@@ -249,6 +250,7 @@ def create_handler(
         monitor.name = model.Name
     if model.Tags is not None:
         monitor.tags = model.Tags
+    _copy_stack_tags(monitor, request)
     if model.Priority is not None:
         monitor.priority = model.Priority
     if model.RestrictedRoles is not None:
@@ -333,3 +335,22 @@ def build_monitor_options_from_model(model: ResourceModel) -> ApiMonitorOptions:
             options.threshold_windows.recovery_window = model.Options.ThresholdWindows.RecoveryWindow
 
     return options
+
+
+def _copy_stack_tags(monitor: ApiMonitor, request: ResourceHandlerRequest):
+    if request.typeConfiguration.TagResourceWithStackTags:
+        tags_to_copy = dict(**request.systemTags)
+        if request.desiredResourceTags:
+            tags_to_copy.update(**request.desiredResourceTags)
+
+        monitor.tags = monitor.get("tags", [])
+        for k, v in tags_to_copy.items():
+            # we also replace the : in the tag name to avoid issues with datadog's tagging format
+            k = k.replace(':', '_')
+            found = False
+            for existing_tag in monitor.tags:
+                if existing_tag.startswith(f"{k}:"):
+                    found = True
+                    break
+            if not found:
+                monitor.tags.append(f"{k}:{v}")

datadog-monitors-monitor-handler/src/datadog_monitors_monitor/models.py

@@ -221,6 +221,7 @@ def _deserialize(
 @dataclass
 class TypeConfigurationModel(BaseModel):
     DatadogCredentials: Optional["_DatadogCredentials"]
+    TagResourceWithStackTags: Optional[bool]
 
     @classmethod
     def _deserialize(
@@ -231,6 +232,7 @@ def _deserialize(
             return None
         return cls(
             DatadogCredentials=DatadogCredentials._deserialize(json_data.get("DatadogCredentials")),
+            TagResourceWithStackTags=json_data.get("TagResourceWithStackTags"),
         )