[Config Service] Expose serverless contextRef

docs/developer/architecture/core/configuration-service.asciidoc

@@ -147,3 +147,64 @@ export const config: PluginConfigDescriptor<ConfigType> = {
   ],
 };
 ----
+[[validating-your-configuration-based-on-context-references]]
+=== Validating your configuration based on context references
+Some features require special configuration when running in different modes (dev/prod/dist, or even serverless). For purpose, core injects the following _references_ in the validation's context:
+
+[cols="^1,^1,3"]
+|===
+|Context Reference |Potential values |Description
+
+|`dev`
+|`true`\|`false`
+|Is Kibana running in Dev mode?
+
+|`prod`
+|`true`\|`false`
+|Is Kibana running in Production mode (running from binary)?
+
+|`dist`
+|`true`\|`false`
+|Is Kibana running from a distributable build (not running from source)?
+
+|`serverless`
+|`true`\|`false`
+|Is Kibana running in Serverless offering?
+
+|`version`
+|`8.9.0`
+|The current version of Kibana
+
+|`buildNum`
+|`12345`
+|The build number
+
+|`branch`
+|`main`
+|The current branch running
+
+|`buildSha`
+|`12345`
+|The build SHA (typically refers to the last commit's SHA)
+
+|===
+
+To use any of the references listed above in a config validation schema, they can be accessed via `schema.contextRef('{CONTEXT_REFERENCE}')`:
+
+[source,js]
+----
+export const config = {
+  schema: schema.object({
+    // Enabled by default in Dev mode
+    enabled: schema.boolean({ defaultValue: schema.contextRef('dev') }),
+
+    // Setting only allowed in the Serverless offering
+    plansForWorldPeace: schema.conditional(
+      schema.contextRef('serverless'),
+      true,
+      schema.string({ defaultValue: 'Free hugs' }),
+      schema.never()
+    ),
+  }),
+};
+----

packages/core/elasticsearch/core-elasticsearch-server-internal/src/elasticsearch_config.ts

@@ -154,7 +154,8 @@ export const configSchema = schema.object({
           return '"ignoreVersionMismatch" can only be set to true in development mode';
         }
       },
-      defaultValue: false,
+      // When running in serverless mode, default to `true`
+      defaultValue: schema.contextRef('serverless'),
     }),
     schema.boolean({ defaultValue: false })
   ),

packages/core/elasticsearch/core-elasticsearch-server-internal/src/elasticsearch_service.ts

@@ -97,8 +97,7 @@ export class ElasticsearchService
     const esNodesCompatibility$ = pollEsNodesVersion({
       internalClient: this.client.asInternalUser,
       log: this.log,
-      ignoreVersionMismatch:
-        config.ignoreVersionMismatch || this.coreContext.env.cliArgs.serverless === true,
+      ignoreVersionMismatch: config.ignoreVersionMismatch,
       esVersionCheckInterval: config.healthCheckDelay.asMilliseconds(),
       kibanaVersion: this.kibanaVersion,
     }).pipe(takeUntil(this.stop$), shareReplay({ refCount: true, bufferSize: 1 }));

packages/core/test-helpers/core-test-helpers-kbn-server/src/create_root.ts

@@ -197,7 +197,7 @@ export interface TestKibanaUtils {
 
 export interface TestUtils {
   startES: () => Promise<TestElasticsearchUtils>;
-  startKibana: () => Promise<TestKibanaUtils>;
+  startKibana: (abortSignal?: AbortSignal) => Promise<TestKibanaUtils>;
 }
 
 /**
@@ -261,7 +261,7 @@ export function createTestServers({
   // Add time for KBN and adding users
   adjustTimeout(es.getStartTimeout() + 100000);
 
-  const kbnSettings = settings.kbn ?? {};
+  const { cliArgs = {}, customKibanaVersion, ...kbnSettings } = settings.kbn ?? {};
 
   return {
     startES: async () => {
@@ -284,8 +284,10 @@ export function createTestServers({
         password: kibanaServerTestUser.password,
       };
     },
-    startKibana: async () => {
-      const root = createRootWithCorePlugins(kbnSettings);
+    startKibana: async (abortSignal?: AbortSignal) => {
+      const root = createRootWithCorePlugins(kbnSettings, cliArgs, customKibanaVersion);
+
+      abortSignal?.addEventListener('abort', async () => await root.shutdown());
 
       await root.preboot();
       const coreSetup = await root.setup();

packages/kbn-config/src/config_service.ts

@@ -241,6 +241,7 @@ export class ConfigService {
       {
         dev: this.env.mode.dev,
         prod: this.env.mode.prod,
+        serverless: this.env.cliArgs.serverless === true,
         ...this.env.packageInfo,
       },
       `config validation of [${namespace}]`

packages/kbn-test/src/es/test_es_cluster.ts

@@ -56,7 +56,7 @@ export interface CreateTestEsClusterOptions {
   clusterName?: string;
   /**
    * Path to data archive snapshot to run Elasticsearch with.
-   * To prepare the the snapshot:
+   * To prepare the snapshot:
    * - run Elasticsearch server
    * - index necessary data
    * - stop Elasticsearch server

src/core/server/integration_tests/elasticsearch/client.test.ts

@@ -68,7 +68,6 @@ function createFakeElasticsearchServer() {
   return server;
 }
 
-// FLAKY: https://github.com/elastic/kibana/issues/129754
 describe('fake elasticsearch', () => {
   let esServer: http.Server;
   let kibanaServer: Root;

src/core/server/integration_tests/elasticsearch/version_compatibility.test.ts

@@ -0,0 +1,135 @@
+/*
+ * 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 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import {
+  createTestServers,
+  type TestElasticsearchUtils,
+  type TestKibanaUtils,
+} from '@kbn/core-test-helpers-kbn-server';
+import { esTestConfig } from '@kbn/test';
+import { firstValueFrom, Subject } from 'rxjs';
+import { CliArgs } from '@kbn/config';
+import Semver from 'semver';
+
+function nextMinor() {
+  return Semver.inc(esTestConfig.getVersion(), 'minor') || '10.0.0';
+}
+
+function previousMinor() {
+  const [major, minor] = esTestConfig
+    .getVersion()
+    .split('.')
+    .map((s) => parseInt(s, 10));
+  // We should be fine for now. When we jump to the next major, we'll need to handle that.
+  return `${major}.${minor - 1}.0`;
+}
+
+describe('Version Compatibility', () => {
+  let esServer: TestElasticsearchUtils | undefined;
+  let kibanaServer: TestKibanaUtils | undefined;
+  let abortController: AbortController | undefined;
+  let consoleSpy: jest.SpyInstance;
+
+  beforeEach(() => {
+    consoleSpy = jest.spyOn(console, 'log');
+  });
+
+  afterEach(async () => {
+    consoleSpy.mockRestore();
+    if (kibanaServer) {
+      await kibanaServer.stop();
+    } else {
+      abortController?.abort();
+    }
+    if (esServer) {
+      await esServer.stop();
+    }
+    kibanaServer = undefined;
+    abortController = undefined;
+    esServer = undefined;
+  });
+
+  const startServers = async ({
+    cliArgs,
+    customKibanaVersion,
+    ignoreVersionMismatch,
+  }: {
+    cliArgs?: Partial<CliArgs>;
+    customKibanaVersion?: string;
+    ignoreVersionMismatch?: boolean;
+  } = {}) => {
+    const { startES, startKibana } = createTestServers({
+      adjustTimeout: jest.setTimeout,
+      settings: {
+        kbn: {
+          cliArgs,
+          customKibanaVersion,
+          elasticsearch: {
+            ignoreVersionMismatch,
+          },
+        },
+      },
+    });
+
+    esServer = await startES();
+    abortController = new AbortController();
+    kibanaServer = await startKibana(abortController.signal);
+  };
+
+  it('should start when versions match', async () => {
+    await expect(startServers({})).resolves.toBeUndefined();
+  });
+
+  it('should start when ES is next minor', async () => {
+    await expect(startServers({ customKibanaVersion: previousMinor() })).resolves.toBeUndefined();
+  });
+
+  it('should flag the incompatibility on version mismatch (ES is previous minor)', async () => {
+    const found$ = new Subject<void>();
+    consoleSpy.mockImplementation((str) => {
+      if (str.includes('is incompatible')) {
+        found$.next();
+      }
+    });
+    await Promise.race([
+      firstValueFrom(found$),
+      startServers({ customKibanaVersion: nextMinor() }).then(() => {
+        throw new Error(
+          'Kibana completed the bootstrap without finding the incompatibility message'
+        );
+      }),
+      new Promise((resolve, reject) =>
+        setTimeout(() => reject(new Error('Test timedout')), 5 * 60 * 1000)
+      ),
+    ]).finally(() => found$.complete());
+  });
+
+  it('should ignore the version mismatch when option is set', async () => {
+    await expect(
+      startServers({
+        customKibanaVersion: nextMinor(),
+        cliArgs: { dev: true },
+        ignoreVersionMismatch: true,
+      })
+    ).resolves.toBeUndefined();
+  });
+
+  it('should not allow the option when not in dev mode', async () => {
+    await expect(
+      startServers({ customKibanaVersion: nextMinor(), ignoreVersionMismatch: true })
+    ).rejects.toThrowErrorMatchingInlineSnapshot(
+      `"[config validation of [elasticsearch].ignoreVersionMismatch]: \\"ignoreVersionMismatch\\" can only be set to true in development mode"`
+    );
+  });
+
+  it('should ignore version mismatch when running on serverless mode and complete startup', async () => {
+    await expect(
+      startServers({ customKibanaVersion: nextMinor(), cliArgs: { serverless: true } })
+    ).resolves.toBeUndefined();
+  });
+});