Adds index action as built-in action (elastic#41592)

* Adds index action as built-in action

* resolve PR comments

- moved `nullableType` to a module so it can be reused across action types
- changed index action param `body` to `documents`, and it's no longer an
  object or array, it's only an array
- rename index action param `execution_time_field` to `executionTimeField`
- remove index action param `doc_id` as it's no longer relevant (only useful
  in the single document story previously)

x-pack/legacy/plugins/actions/README.md

@@ -175,6 +175,7 @@ Kibana ships with a set of built-in action types:
 - server log: logs messages to the Kibana log using `server.log()`
 - email: send an email
 - slack: post a message to a slack channel
+- index: index document(s) into elasticsearch
 
 ## server log, action id: `.log`
 
@@ -247,6 +248,27 @@ This action type interfaces with the [Slack Incoming Webhooks feature](https://a
 |---|---|---|
 |message|the message text|string|
 
+
+## index, action id: `.index`
+
+The config and params properties are modelled after the [Watcher Index Action](https://www.elastic.co/guide/en/elastic-stack-overview/master/actions-index.html).  The index can be set in the config or params, and if set in config, then the index set in the params will be ignored.
+
+#### config properties
+
+|Property|Description|Type|
+|---|---|---|
+|index|The Elasticsearch index to index into.|string _(optional)_|
+
+#### params properties
+
+|Property|Description|Type|
+|---|---|---|
+|index|The Elasticsearch index to index into.|string _(optional)_|
+|doc_id|The optional _id of the document.|string _(optional)_|
+|execution_time_field|The field that will store/index the action execution time.|string _(optional)_|
+|refresh|Setting of the refresh policy for the write request|boolean _(optional)_|
+|body|The documument body/bodies to index.|object or object[]|
+
 # Command Line Utility
 
 The [`kbn-action`](https://github.com/pmuellr/kbn-action) tool can be used to send HTTP requests to the Actions plugin.  For instance, to create a Slack action from the `.slack` Action Type, use the following command:

x-pack/legacy/plugins/actions/server/builtin_action_types/email.test.ts

@@ -185,7 +185,8 @@ describe('execute()', () => {
       message: 'a message to you',
     };
 
-    const executorOptions: ActionTypeExecutorOptions = { config, params, services };
+    const id = 'some-id';
+    const executorOptions: ActionTypeExecutorOptions = { id, config, params, services };
     sendEmailMock.mockReset();
     await actionType.executor(executorOptions);
     expect(sendEmailMock.mock.calls[0][1]).toMatchInlineSnapshot(`

x-pack/legacy/plugins/actions/server/builtin_action_types/email.ts

@@ -4,18 +4,15 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-import { schema, TypeOf, Type } from '@kbn/config-schema';
+import { schema, TypeOf } from '@kbn/config-schema';
 import nodemailerServices from 'nodemailer/lib/well-known/services.json';
 
 import { sendEmail, JSON_TRANSPORT_SERVICE } from './lib/send_email';
+import { nullableType } from './lib/nullable';
 import { ActionType, ActionTypeExecutorOptions, ActionTypeExecutorResult } from '../types';
 
 const PORT_MAX = 256 * 256 - 1;
 
-function nullableType<V>(type: Type<V>) {
-  return schema.oneOf([type, schema.literal(null)], { defaultValue: () => null });
-}
-
 // config definition
 
 const unencryptedConfigProperties = ['service', 'host', 'port', 'secure', 'from'];
@@ -108,6 +105,7 @@ export const actionType: ActionType = {
 // action executor
 
 async function executor(execOptions: ActionTypeExecutorOptions): Promise<ActionTypeExecutorResult> {
+  const id = execOptions.id;
   const config = execOptions.config as ActionTypeConfigType;
   const params = execOptions.params as ActionParamsType;
   const services = execOptions.services;
@@ -146,7 +144,7 @@ async function executor(execOptions: ActionTypeExecutorOptions): Promise<ActionT
   } catch (err) {
     return {
       status: 'error',
-      message: `error sending email: ${err.message}`,
+      message: `error in action ${id} sending email: ${err.message}`,
     };
   }