azure docs

docs/azure/identify-untagged-resources.md

@@ -0,0 +1,28 @@
+# Identify Untagged Resources
+
+Tagging in Azure is essential for managing resouces, billing, ownership and more. As a general rule it's important to ensure that all resources are tagged. 
+
+To identify untagged resources we can use the Resource Graph Explorer in Azure. This allows us to query across all our resources and filter for those that do not have tags.
+
+## Query for Untagged Resources
+
+1. Navigate to the Azure Portal and open the Resource Graph Explorer.
+2. Use the following Kusto Query Language (KQL) query to find untagged resources:
+
+```kql
+resources
+| where isnull(tags) or tostring(tags) == '[]'
+| project name, type, resourceGroup, location
+```
+
+## Recording management
+
+Personally I like to tag all resources with a `managed_by` tag to indicate who or what is responsible for creating/updating the resource (e.g. `manual` or `terraform` or `pulumi` etc). 
+
+To identify resources that are not tagged with `managed_by` we can use the following query:
+
+```kql
+resources
+| where tags !has 'managed_by'
+| project name, type, resourceGroup, location
+```