Add new data streams scenario

Author: alexandra5000

reference/fleet/data-streams-ilm-tutorial.md

@@ -26,4 +26,5 @@ How you apply an ILM policy depends on your use case. Choose a scenario for the
 
 * **[Scenario 1](/reference/fleet/data-streams-scenario1.md)**: You want to apply an ILM policy to all logs or metrics data streams across all namespaces.
 * **[Scenario 2](/reference/fleet/data-streams-scenario2.md)**: You want to apply an ILM policy to selected data streams in an integration.
-* **[Scenario 3](/reference/fleet/data-streams-scenario3.md)**: You want apply an ILM policy for data streams in a selected namespace in an integration.
+* **[Scenario 3](/reference/fleet/data-streams-scenario3.md)**: You want to apply an ILM policy for data streams in a selected namespace in an integration.
+* **[Scenario 4](/reference/fleet/data-streams-scenario4.md)** (9.1+): Apply an ILM policy to all data streams in a custom integration using a `@custom` component template.

reference/fleet/data-streams-scenario4.md

@@ -0,0 +1,62 @@
+---
+navigation_title: Scenario 4
+mapped_pages:
+  - https://www.elastic.co/guide/en/fleet/current/data-streams-scenario4.html
+products:
+  - id: fleet
+  - id: elastic-agent
+---
+
+# Scenario 4: Apply an ILM policy to all data streams in a custom integration [data-streams-scenario4]
+
+If you’ve created a custom integration package, you can apply a single ILM policy to all its data streams using a shared `@custom` component template. This eliminates the need to configure each data stream individually.
+
+:::{note}
+This method is available in version 9.1 and later.
+:::
+
+## Step 1: Define the ILM policy [data-streams-scenario4-step1]
+
+1. In {{kib}}, go to **Stack Management** and select **Index Lifecycle Policies**. You can also use the [global search field](/get-started/the-stack.md#kibana-navigation-search).
+2. Click **Create policy**.
+3. Name the policy, configure it as needed, and click **Save policy**.
+
+## Step 2: Create a custom component template [data-streams-scenario4-step2]
+
+Create a custom component template named `<integration>@custom`, replacing `<integration>` with your package name.
+
+For example, for a Docker integration, use:
+
+```json
+PUT _component_template/docker@custom
+{
+  "template": {
+    "settings": {
+      "index": {
+        "lifecycle": {
+          "name": "docker-ilm-policy"
+        }
+      }
+    },
+    "mappings": {
+      "properties": {
+        "@timestamp": {
+          "type": "date"
+        }
+      }
+    }
+  }
+}
+```
+
+## Step 3: Deploy or update the integration [data-streams-scenario4-step3]
+
+The `@custom` component template is automatically included when the package is installed or updated.
+
+To apply the ILM policy:
+
+- Bump the version of your custom package.
+
+- Reinstall or upgrade the package using the Fleet UI or Developer Console.
+
+After it has been deployed, the ILM policy from `docker@custom` will apply to all data streams in the package.