Integrate core CLI with repl.

src/core/cli/cli.ts

@@ -32,7 +32,11 @@ import { LoggingConfig } from '../server/logging';
 import { MutableLoggerFactory } from '../server/logging/logger_factory';
 import { LoggingService } from '../server/logging/logging_service';
 import * as args from './args';
-import { CLUSTER_MANAGER_PATH, detectInstallationFeatures } from './installation_features';
+import {
+  CLUSTER_MANAGER_PATH,
+  detectInstallationFeatures,
+  REPL_PATH,
+} from './installation_features';
 import { overrideConfigWithArgv } from './override_config_with_argv';
 import { createServeCommand } from './serve';
 
@@ -130,12 +134,19 @@ export const run = (argv: string[]) => {
       }
 
       const KbnServer = require('../../server/kbn_server');
-      const legacyService = new LegacyService(
-        env,
-        loggerFactory,
-        configService,
-        new KbnServer(rawConfig.getRaw(), env.legacy)
-      );
+      const kbnServer = new KbnServer(rawConfig.getRaw(), env.legacy);
+      const legacyService = new LegacyService(env, loggerFactory, configService, kbnServer);
+
+      if (parsedArgs.repl) {
+        if (!installationFeatures.isReplModeSupported) {
+          throw new Error('Kibana REPL mode can only be run in development mode.');
+        } else if (process.env.kbnWorkerType === 'server') {
+          // The kbnWorkerType check is necessary to prevent the repl
+          // from being started multiple times in different processes.
+          // We only want one REPL.
+          require(REPL_PATH).startRepl(kbnServer);
+        }
+      }
 
       const root = new Root(
         configService,