system/network: Fix interfaces filtering (#15883)

Author: shmsr

packages/system/changelog.yml

@@ -1,4 +1,9 @@
 # newer versions go on top
+- version: "2.7.1"
+  changes:
+    - description: Fix network data stream interface filtering by populating both legacy top-level `interfaces` and nested `network.interfaces` fields.
+      type: bugfix
+      link: https://github.com/elastic/integrations/pull/15883
 - version: "2.7.0"
   changes:
     - description: Add NTP data stream.

packages/system/data_stream/network/agent/stream/stream.yml.hbs

@@ -1,5 +1,11 @@
 metricsets: ["network"]
 period: {{period}}
+{{! Populate both 'interfaces' and 'network.interfaces'. Beats currently exposes 'interfaces' as a top-level field instead of nesting it under 'network', so duplicating it keeps existing Beats behavior working. Once Beats aligns on the nested field, we can drop the legacy top-level field. }}
+interfaces:
+{{#each network.interfaces}}
+- {{this}}
+{{/each}}
+{{! 'network.interfaces' is currently being populated for future use or compatibility, but may not be actively used by Beats yet. }}
 network.interfaces:
 {{#each network.interfaces}}
 - {{this}}

packages/system/data_stream/network/manifest.yml

@@ -19,8 +19,7 @@ streams:
         required: false
         show_user: true
         description: >
-          List of interfaces to monitor. Will monitor all by default.
-
+          List of interfaces to monitor. If not set, all interfaces are monitored by default.
       - name: tags
         type: text
         title: Tags

packages/system/manifest.yml

@@ -1,7 +1,7 @@
 format_version: 3.0.2
 name: system
 title: System
-version: "2.7.0"
+version: "2.7.1"
 description: Collect system logs and metrics from your servers with Elastic Agent.
 type: integration
 categories: