kubernetes-health/dist/probes.js

Helper library for implementing Kubernetes heath checks and graceful HTTP shutdown in Node applications

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.startProbeServer = exports.createProbeServer = exports.createReadinessProbeListener = exports.createLivenessProbeListener = void 0;
const http_1 = __importDefault(require("http"));
const url_1 = require("url");
function requestListenerToProbeListener(requestListener) {
    const probeListener = ((req, res) => {
        // http.Server, Express, Connect
        if (res instanceof http_1.default.ServerResponse) {
            return requestListener({}, res);
        }
        // Fastify
        if ('raw' in res && res.raw instanceof http_1.default.ServerResponse) {
            return requestListener({}, res.raw);
        }
        // Koa
        if (req && 'res' in req && req.res instanceof http_1.default.ServerResponse) {
            return requestListener({}, req.res);
        }
    });
    return probeListener;
}
/**
 * Creates a new `ProbeListener` that returns 200 if the specified `Health` instance is live, and 500 otherwise.
 *
 * @param health the `Health` instance
 * @returns an `ProbeListener`
 */
function createLivenessProbeListener(health) {
    return requestListenerToProbeListener((_, res) => {
        if (health.isLive) {
            res.statusCode = 200;
            res.end('live');
        }
        else {
            res.statusCode = 500;
            res.end('not live');
        }
    });
}
exports.createLivenessProbeListener = createLivenessProbeListener;
/**
 * Creates a new `ProbeListener` that returns 200 if the specified `Health` instance is ready, and 500 otherwise.
 *
 * @param health the `Health` instance
 * @returns an `ProbeListener`
 */
function createReadinessProbeListener(health) {
    return requestListenerToProbeListener((_, res) => {
        if (health.isReady) {
            res.statusCode = 200;
            res.end('ready');
        }
        else {
            res.statusCode = 500;
            res.end('not ready');
        }
    });
}
exports.createReadinessProbeListener = createReadinessProbeListener;
/**
 * Creates a new `http.Server` configured to serve the liveness and readiness endpoints for a given Health instance.
 *
 * @param health the `Health` instance to serve
 * @param options options for the health probe server
 * @returns an `http.Server` ready to serve the health probes
 */
function createProbeServer(health, options = {}) {
    const { livenessEndpoint = '/healthz', readinessEndpoint = '/readyz' } = options;
    const livenessListener = createLivenessProbeListener(health);
    const readinessListener = createReadinessProbeListener(health);
    return http_1.default.createServer((req, res) => {
        const url = new url_1.URL(req.url, `http://${req.headers.host}`);
        if (url.pathname === livenessEndpoint)
            return livenessListener(req, res);
        if (url.pathname === readinessEndpoint)
            return readinessListener(req, res);
        res.statusCode = 404;
        res.end('not found');
    });
}
exports.createProbeServer = createProbeServer;
/**
 * Create and start a health probe server, listening on on the specified port / hostname.
 *
 * @param health the `Health` instance to serve
 * @param options options for the health probe server
 */
function startProbeServer(health, options = {}) {
    const { port = 4000, hostname } = options;
    const server = createProbeServer(health, options);
    return server.listen(port, hostname);
}
exports.startProbeServer = startProbeServer;
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