Create alerting plugin

[mikecote]

In this PR, we're introducing the alerting kibana plugin with basic functionality. The basic functionality includes the ability to register alert types and CRUD operations for alerts. The alerts are saved objects alongside a referenceable task manager instance, as they get created, they are scheduled.

The plugin will expose the following functions (via server.plugins.alerting):

• registerType({ id, description, execute })
• listTypes()

The request has a new function request.getAlertsClient() which returns an instance of the client with the following functions:

• create({ data, options })
• get({ id })
• find({ options })
• delete({ id })
• update({ id, data, options })

The actions plugin is modified to fire through the task manager instead of calling action type executors directly.

Example creation of an alert type

server.plugins.alerting.registerType({
  id: 'my-alert-type',
  name: 'My alert type',
  validate: {
    params: Joi.object()
      .keys({
        myParam: Joi.string().required(),
      })
      .required(),
  },
  async execute({
    scheduledRunAt,
    previousScheduledRunAt,
    services,
    params,
    state,
  }: AlertExecuteOptions) {
    // Pass in parameters, also validated
    const {
      myParam
    } = params;

    // Available services
    const {
      log,
      callCluster,
      savedObjectsClient,
      alertInstanceFactory,
    } = services;
  
    // Firing actions
    alertInstanceFactory('server_1')
      .replaceState({
        // Alert instance level state, use getState() for
        // previous and persisted values
        ...
      })
      .fire('default', {
        server: 'server_1',
      });
    
    // Returning updated alert type level state
    return {
      ...
    };
  },
});

[bmcconaghy]

LGTM. I think there are a few things to refine here, but we can do that work in smaller, more focused PRs after this gets merged.

[azasypkin]

Finished reviewing actions, encrypted_saved_objects and task_manager parts of the PR that are relevant to encrypted_saved_objects. Still reviewing the actual alerting part, but wanted to share a preliminary feedback I have already (mostly nits, questions and one Joi-related concern).

[peterschretlen]

Overall looks good 👍 I left one comment about firing actions on the alert instances at larger scale. But in terms of API, plugin, interfaces look good to me.

[elasticmachine]

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• continuous-integration/kibana-ci/pull-request