@mdf.js/service-registry
Version:
MMS - API - Service Registry
114 lines • 5.32 kB
TypeScript
/**
* Copyright 2024 Mytra Control S.L. All rights reserved.
*
* Use of this source code is governed by an MIT-style license that can be found in the LICENSE file
* or at https://opensource.org/licenses/MIT.
*/
import { Health, Layer } from '@mdf.js/core';
import { LoggerInstance } from '@mdf.js/logger';
import EventEmitter from 'events';
/**
* The Aggregator class serves as a central point for collecting and aggregating health checks
* and statuses from various components within an application. It also allows for the integration
* of external and worker-specific checks to provide a comprehensive view of the application's
* health status.
*
* This class extends EventEmitter to emit status updates, enabling other parts of the application
* to react to changes in health status as necessary.
*/
export declare class Aggregator extends EventEmitter {
private readonly metadata;
private readonly logger;
/** Components monitored by the aggregator */
private readonly components;
/** External checks, included in the aggregator to be exposed in the overall diagnostic */
private readonly externalChecks;
/** Worker checks, included in the aggregator to be exposed in the overall diagnostic */
private readonly workerChecks;
/** Base Health Status*/
protected readonly baseHealth: Omit<Layer.App.Health, 'status' | 'checks'>;
/** Array of notes to be included in the health status */
private readonly notes;
/** Public output */
output: string | undefined;
/**
* Create an instance of the Health aggregator
* @param metadata - Metadata describing the application, used to enrich the health data.
* @param logger - Logger instance for logging activities related to health monitoring.
*/
constructor(metadata: Layer.App.Metadata, logger: LoggerInstance);
/**
* Computes the health status of the application by aggregating individual component checks
* and determining the overall status.
*/
get health(): Layer.App.Health;
/**
* Aggregates checks from all sources: registered components, external checks, and worker checks.
*/
get checks(): Health.Checks;
/** Overall component status */
get status(): Health.Status;
/**
* Register a resource or a list of resources to monitor for errors.
* @param component - Resource or list of resources to be registered
*/
register(component: Layer.App.Resource | Layer.App.Resource[]): void;
/**
* Adds a timestamped note to the health status.
* @param note - Note to be added.
*/
addNote(note: string): void;
/**
* Update or add a check measure.
* This should be used to inform about the state of resources behind the Component/Microservice,
* for example states of connections with field devices.
*
* The new check will be taking into account in the overall health status.
* The new check will be included in the `checks` object with the key "component:measure".
* If this key already exists, the `componentId` of the `check` parameter will be checked, if
* there is a check with the same `componentId` in the array, the check will be updated, in other
* case the new check will be added to the existing array.
*
* The maximum number external checks entries is 10, and the maximum number of checks per entry
* is 100.
* @param component - component identification
* @param measure - measure identification
* @param check - check to be updated or included
* @returns true, if the check has been updated or included
*/
addExternalCheck(component: string, measure: string, check: Health.Check): boolean;
/**
* Update the health checks associated with workers.
* @param checks - Checks to be updated or included
*/
updateWorkersChecks(checks: Health.Checks): void;
/**
* Update or add a check measure for a worker.
* This should be used to inform about the state of resources behind the worker.
* The new check will be taking into account in the overall health status.
* The new check will be included in the `checks` object with the key "component:measure".
* If this key already exists, the `componentId` of the `check` parameter will be checked, if
* there is a check with the same `componentId` in the array, the check will be updated, in other
* case the new check will be added to the existing array.
* @param component - component identification
* @param measure - measure identification
* @param check - check to be updated or included
* @returns true, if the check has been updated or included
*/
addWorkerCheck(component: string, measure: string, check: Health.Check): boolean;
/** Event handler for status event */
private readonly statusEventHandler;
/**
* Check if the check is valid to be included in the health status
* @param check - Check to be validated
* @returns
*/
private isValidCheck;
/** Check if the resource is valid to be monitored */
private isValidResource;
/** Return the the uptime of service as a check */
private get uptime();
/** Close the aggregator */
close(): void;
}
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