add unknowns: ignore for serverless config

x-pack/plugins/cloud/server/config.test.ts

@@ -0,0 +1,23 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { config } from './config';
+
+describe('Cloud plugin config', () => {
+  it('evicts unknown properties under the `serverless` structure', () => {
+    const output = config.schema.validate({
+      serverless: {
+        project_id: 'project_id',
+        unknown_prop: 'some unknown prop',
+      },
+    });
+
+    expect(output.serverless).toEqual({
+      project_id: 'project_id',
+    });
+  });
+});

x-pack/plugins/cloud/server/config.ts

@@ -33,10 +33,14 @@ const configSchema = schema.object({
   trial_end_date: schema.maybe(schema.string()),
   is_elastic_staff_owned: schema.maybe(schema.boolean()),
   serverless: schema.maybe(
-    schema.object({
-      project_id: schema.string(),
-      project_name: schema.maybe(schema.string()),
-    })
+    schema.object(
+      {
+        project_id: schema.string(),
+        project_name: schema.maybe(schema.string()),
+      },
+      // avoid future chicken-and-egg situation with the component populating the config
+      { unknowns: 'ignore' }
+    )
   ),
 });