[Logs+] Add support for logs@custom component template (#95481)

Author: eyalkoren

docs/changelog/95481.yaml

@@ -0,0 +1,6 @@
+pr: 95481
+summary: "Add support for `logs@custom` component template for `logs-*-* data streams"
+area: Data streams
+type: enhancement
+issues:
+ - 95469

modules/data-streams/src/yamlRestTest/resources/rest-api-spec/test/data_stream/210_logs_custom_mappings.yml

@@ -0,0 +1,37 @@
+---
+"Basic logs@custom component template functionality test":
+ - do:
+ cluster.put_component_template:
+ name: logs@custom
+ body:
+ template:
+ settings:
+ index:
+ query:
+ default_field: [ "custom-message" ]
+ mappings:
+ properties:
+ numeric_field:
+ type: integer
+
+ - do:
+ indices.create_data_stream:
+ name: logs-generic-default
+ - is_true: acknowledged
+
+ - do:
+ indices.get_data_stream:
+ name: logs-generic-default
+ - set: { data_streams.0.indices.0.index_name: idx0name }
+
+ - do:
+ indices.get_settings:
+ index: $idx0name
+ # verify that the custom settings.index.query.default_field overrides the default query field - "message"
+ - match: { .$idx0name.settings.index.query.default_field: ["custom-message"] }
+
+ - do:
+ indices.get_mapping:
+ index: $idx0name
+ # verify that the new field from the custom component template is applied
+ - match: { .$idx0name.mappings.properties.numeric_field.type: "integer" }

x-pack/plugin/core/src/main/resources/logs-template.json

@@ -5,8 +5,10 @@
  "composed_of": [
  "logs-mappings",
  "data-streams-mappings",
- "logs-settings"
+ "logs-settings",
+ "logs@custom"
  ],
+ "ignore_missing_component_templates": ["logs@custom"],
  "allow_auto_create": true,
  "_meta": {
  "description": "default logs template installed by x-pack",