[Alerting] Enforces typing of Alert's ActionGroups (elastic#86761)

This PR tightens the typing on the Alerting framework's `AlertType` and its deeper typing around `AlertServices ` and `AlertExecutorOptions`.

This ensures the following:

1. It's now impossible<sup>✴</sup> to schedule actions on any ActionGroup other than the groups specified on the AlertType (including the Recovery group)
2. It's now impossible<sup>✴</sup> to schedule actions with incorrect `InstanceState` or `InstanceContext`

✴ Unless they bypass the Typescript typing, which is an explicit choice to bypass type safety

x-pack/examples/alerting_example/common/constants.ts

@@ -10,15 +10,16 @@ export const ALERTING_EXAMPLE_APP_ID = 'AlertingExample';
 
 // always firing
 export const DEFAULT_INSTANCES_TO_GENERATE = 5;
+export interface AlwaysFiringThresholds {
+  small?: number;
+  medium?: number;
+  large?: number;
+}
 export interface AlwaysFiringParams extends AlertTypeParams {
   instances?: number;
-  thresholds?: {
-    small?: number;
-    medium?: number;
-    large?: number;
-  };
+  thresholds?: AlwaysFiringThresholds;
 }
-export type AlwaysFiringActionGroupIds = keyof AlwaysFiringParams['thresholds'];
+export type AlwaysFiringActionGroupIds = keyof AlwaysFiringThresholds;
 
 // Astros
 export enum Craft {

x-pack/examples/alerting_example/public/alert_types/always_firing.tsx

@@ -133,8 +133,10 @@ export const AlwaysFiringExpression: React.FunctionComponent<
 };
 
 interface TShirtSelectorProps {
-  actionGroup?: ActionGroupWithCondition<number>;
-  setTShirtThreshold: (actionGroup: ActionGroupWithCondition<number>) => void;
+  actionGroup?: ActionGroupWithCondition<number, AlwaysFiringActionGroupIds>;
+  setTShirtThreshold: (
+    actionGroup: ActionGroupWithCondition<number, AlwaysFiringActionGroupIds>
+  ) => void;
 }
 const TShirtSelector = ({ actionGroup, setTShirtThreshold }: TShirtSelectorProps) => {
   const [isOpen, setIsOpen] = useState(false);

x-pack/examples/alerting_example/server/alert_types/always_firing.ts

@@ -11,6 +11,7 @@ import {
   DEFAULT_INSTANCES_TO_GENERATE,
   ALERTING_EXAMPLE_APP_ID,
   AlwaysFiringParams,
+  AlwaysFiringActionGroupIds,
 } from '../../common/constants';
 
 type ActionGroups = 'small' | 'medium' | 'large';
@@ -39,7 +40,8 @@ export const alertType: AlertType<
   AlwaysFiringParams,
   { count?: number },
   { triggerdOnCycle: number },
-  never
+  never,
+  AlwaysFiringActionGroupIds
 > = {
   id: 'example.always-firing',
   name: 'Always firing',

x-pack/examples/alerting_example/server/alert_types/astros.ts

@@ -41,7 +41,10 @@ function getCraftFilter(craft: string) {
 export const alertType: AlertType<
   { outerSpaceCapacity: number; craft: string; op: string },
   { peopleInSpace: number },
-  { craft: string }
+  { craft: string },
+  never,
+  'default',
+  'hasLandedBackOnEarth'
 > = {
   id: 'example.people-in-space',
   name: 'People In Space Right Now',

x-pack/plugins/alerts/README.md

@@ -142,8 +142,41 @@ This example receives server and threshold as parameters. It will read the CPU u
 
 ```typescript
 import { schema } from '@kbn/config-schema';
+import {
+	Alert,
+	AlertTypeParams,
+	AlertTypeState,
+	AlertInstanceState,
+	AlertInstanceContext
+} from 'x-pack/plugins/alerts/common';
 ...
-server.newPlatform.setup.plugins.alerts.registerType({
+interface MyAlertTypeParams extends AlertTypeParams {
+	server: string;
+	threshold: number;
+}
+
+interface MyAlertTypeState extends AlertTypeState {
+	lastChecked: number;
+}
+
+interface MyAlertTypeInstanceState extends AlertInstanceState {
+	cpuUsage: number;
+}
+
+interface MyAlertTypeInstanceContext extends AlertInstanceContext {
+	server: string;
+	hasCpuUsageIncreased: boolean;
+}
+
+type MyAlertTypeActionGroups = 'default' | 'warning';
+
+const myAlertType: AlertType<
+	MyAlertTypeParams,
+	MyAlertTypeState,
+	MyAlertTypeInstanceState,
+	MyAlertTypeInstanceContext,
+	MyAlertTypeActionGroups
+> = {
 	id: 'my-alert-type',
 	name: 'My alert type',
 	validate: {
@@ -180,7 +213,7 @@ server.newPlatform.setup.plugins.alerts.registerType({
 		services,
 		params,
 		state,
-	}: AlertExecutorOptions) {
+	}: AlertExecutorOptions<MyAlertTypeParams, MyAlertTypeState, MyAlertTypeInstanceState, MyAlertTypeInstanceContext, MyAlertTypeActionGroups>) {
 		// Let's assume params is { server: 'server_1', threshold: 0.8 }
 		const { server, threshold } = params;
 
@@ -219,7 +252,9 @@ server.newPlatform.setup.plugins.alerts.registerType({
 		};
 	},
 	producer: 'alerting',
-});
+};
+
+server.newPlatform.setup.plugins.alerts.registerType(myAlertType);
 ```
 
 This example only receives threshold as a parameter. It will read the CPU usage of all the servers and schedule individual actions if the reading for a server is greater than the threshold. This is a better implementation than above as only one query is performed for all the servers instead of one query per server.

x-pack/plugins/alerts/common/alert_type.ts

@@ -5,19 +5,29 @@
  */
 
 import { LicenseType } from '../../licensing/common/types';
+import { RecoveredActionGroupId, DefaultActionGroupId } from './builtin_action_groups';
 
-export interface AlertType {
+export interface AlertType<
+  ActionGroupIds extends Exclude<string, RecoveredActionGroupId> = DefaultActionGroupId,
+  RecoveryActionGroupId extends string = RecoveredActionGroupId
+> {
   id: string;
   name: string;
-  actionGroups: ActionGroup[];
-  recoveryActionGroup: ActionGroup;
+  actionGroups: Array<ActionGroup<ActionGroupIds>>;
+  recoveryActionGroup: ActionGroup<RecoveryActionGroupId>;
   actionVariables: string[];
-  defaultActionGroupId: ActionGroup['id'];
+  defaultActionGroupId: ActionGroupIds;
   producer: string;
   minimumLicenseRequired: LicenseType;
 }
 
-export interface ActionGroup {
-  id: string;
+export interface ActionGroup<ActionGroupIds extends string> {
+  id: ActionGroupIds;
   name: string;
 }
+
+export type ActionGroupIdsOf<T> = T extends ActionGroup<infer groups>
+  ? groups
+  : T extends Readonly<ActionGroup<infer groups>>
+  ? groups
+  : never;

x-pack/plugins/alerts/common/builtin_action_groups.ts

@@ -6,13 +6,27 @@
 import { i18n } from '@kbn/i18n';
 import { ActionGroup } from './alert_type';
 
-export const RecoveredActionGroup: Readonly<ActionGroup> = {
+export type DefaultActionGroupId = 'default';
+
+export type RecoveredActionGroupId = typeof RecoveredActionGroup['id'];
+export const RecoveredActionGroup: Readonly<ActionGroup<'recovered'>> = Object.freeze({
   id: 'recovered',
   name: i18n.translate('xpack.alerts.builtinActionGroups.recovered', {
     defaultMessage: 'Recovered',
   }),
-};
+});
+
+export type ReservedActionGroups<RecoveryActionGroupId extends string> =
+  | RecoveryActionGroupId
+  | RecoveredActionGroupId;
+
+export type WithoutReservedActionGroups<
+  ActionGroupIds extends string,
+  RecoveryActionGroupId extends string
+> = ActionGroupIds extends ReservedActionGroups<RecoveryActionGroupId> ? never : ActionGroupIds;
 
-export function getBuiltinActionGroups(customRecoveryGroup?: ActionGroup): ActionGroup[] {
-  return [customRecoveryGroup ?? Object.freeze(RecoveredActionGroup)];
+export function getBuiltinActionGroups<RecoveryActionGroupId extends string>(
+  customRecoveryGroup?: ActionGroup<RecoveryActionGroupId>
+): [ActionGroup<ReservedActionGroups<RecoveryActionGroupId>>] {
+  return [customRecoveryGroup ?? RecoveredActionGroup];
 }