# Terminus

Terminus is a package to adds graceful shutdown and Kubernetes readiness / liveness checks for any HTTP applications. This tutorial will show you how to install and use Terminus with Ts.ED.

# Installation

Before using terminus, we need to install the terminus (opens new window) module.

npm install --save @godaddy/terminus @tsed/terminus

Then import @tsed/terminus and add the following configuration in your Server.ts:

# Options

terminus configuration options waiting the same option description in the official Terminus documentation here (opens new window). The following the options are managed by the @tsed/terminus package:

healthChecks
onSignal
onSendFailureDuringShutdown
onShutdown
beforeShutdown
onSigterm

export type TerminusSettings = Omit<
  TerminusOptions,
  "healthChecks" | "onSignal" | "onSendFailureDuringShutdown" | "onShutdown" | "beforeShutdown" | "onSigterm"
>;

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# Usage

# Readiness / liveness checks

To create a readiness / liveness checks use the @Health decorator.

import {Health} from "@tsed/terminus";

@Controller("/mongo")
class MongoCtrl {
  @Health("/health")
  health() {
    // Here check the mongo health
    return Promise.resolve();
  }
}

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You can also create an HealthCheckError when an error appear during your check.

import {Health} from "@tsed/terminus";
import {HealthCheckError} from "@godaddy/terminus";

@Controller("/redis")
class Redis {
  @Health("/health")
  health() {
    // Here check the redis health
    return Promise.reject(
      new HealthCheckError("failed", {
        redis: "down"
      })
    );
  }
}

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# Graceful shutdown

@tsed/terminus package give some decorators to handle Terminus hooks. These hooks allow you to adds graceful shutdown. Here is the list of decorators:

BeforeShutdown : Use this hook if you deploy your application with Kubernetes (see more details here (opens new window)),
OnSignal : cleanup hook, returning a promise (used to be onSigterm),
OnShutdown : called right before exiting,
OnSendFailureDuringShutdown : called before sending each 503 during shutdowns.

Example:

import {BeforeShutdown, OnSendFailureDuringShutdown, OnShutdown, OnSignal} from "@tsed/terminus";

@Controller("/redis")
class RedisCtrl {
  @BeforeShutdown()
  beforeShutdow() {
    console.log("called before shutdown");
  }

  @OnSignal()
  OnSignal() {
    console.log("called on signal");
  }

  @OnShutdown()
  OnShutdown() {
    console.log("called on shutdown");
  }

  @OnSendFailureDuringShutdown()
  OnSendFailureDuringShutdown() {
    console.log("on send failure during shutdown");
  }
}

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# Author

# Maintainers

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