node: breaking naming changes to match go version

.eslintrc.cjs

@@ -1,17 +0,0 @@
-module.exports = {
-	root: true,
-	env: {
-		node: true,
-		es2021: true,
-	},
-	parser: '@typescript-eslint/parser',
-	plugins: ['@typescript-eslint', 'prettier'],
-	extends: [
-		'eslint:recommended',
-		'plugin:@typescript-eslint/recommended',
-		'plugin:prettier/recommended',
-	],
-	rules: {
-		'prettier/prettier': 'error',
-	},
-};

go-health/liveness.go

@@ -0,0 +1,42 @@
+package health
+
+import (
+	"encoding/json"
+	"net/http"
+	"time"
+)
+
+// Status of the service liveness.
+type LivenessStatus string
+
+const (
+	// Service is alive and functioning properly.
+	LivenessStatusAlive LivenessStatus = "ok"
+)
+
+// Result of a liveness check.
+type LivenessResult struct {
+	// Status of the service (always LivenessStatusAlive)
+	Status LivenessStatus
+	// Timestamp of the liveness check in milliseconds since Unix epoch
+	Timestamp int64
+}
+
+// Checks if the service is alive.
+func Liveness() LivenessResult {
+	return LivenessResult{
+		Status:    LivenessStatusAlive,
+		Timestamp: time.Now().UnixMilli(),
+	}
+}
+
+// Handler for liveness HTTP requests.
+// Returns a response with status 200 and a JSON body matching LivenessResult.
+func LivenessHandler() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		result := Liveness()
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusOK)
+		json.NewEncoder(w).Encode(result)
+	}
+}

go-health/readiness.go

@@ -0,0 +1,221 @@
+package health
+
+import (
+	"encoding/json"
+	"net/http"
+	"slices"
+	"time"
+)
+
+// Status of the service readiness.
+type ReadinessStatus string
+
+// String returns the string representation of the readiness status.
+func (s ReadinessStatus) String() string {
+	return string(s)
+}
+
+// HTTPStatus returns the corresponding HTTP status code for the readiness status.
+func (s ReadinessStatus) HTTPStatus() int {
+	switch s {
+	case ReadinessStatusReady:
+		return http.StatusOK
+	case ReadinessStatusDegraded:
+		return http.StatusOK // 206 could also be suitable, but let's avoid false alarms
+	case ReadinessStatusFatal:
+		return http.StatusServiceUnavailable
+	case ReadinessStatusNotReady:
+		return http.StatusOK // treat as ok to avoid false alarms
+	default:
+		return http.StatusOK
+	}
+}
+
+const (
+	// Service is ready to handle requests.
+	ReadinessStatusReady ReadinessStatus = "ready"
+	// Service is not ready to handle requests.
+	ReadinessStatusNotReady ReadinessStatus = "not_ready"
+	// Service experienced a fatal error and cannot handle requests.
+	ReadinessStatusFatal ReadinessStatus = "fatal"
+	// Service is degraded but can still handle requests.
+	ReadinessStatusDegraded ReadinessStatus = "degraded"
+)
+
+// Returns the worst readiness status from a list of statuses.
+func worstStatus(statuses []ReadinessStatus) ReadinessStatus {
+	if slices.Contains(statuses, ReadinessStatusFatal) {
+		return ReadinessStatusFatal
+	}
+	if slices.Contains(statuses, ReadinessStatusNotReady) {
+		return ReadinessStatusNotReady
+	}
+	if slices.Contains(statuses, ReadinessStatusDegraded) {
+		return ReadinessStatusDegraded
+	}
+	return ReadinessStatusReady
+}
+
+// Readiness check function return type.
+type ReadinessReturn struct {
+	// Status of the readiness check.
+	Status ReadinessStatus
+	// Optional message providing additional information about the readiness status.
+	Message *string
+}
+
+// Function that performs a readiness check.
+type ReadinessCheckFn func() ReadinessReturn
+
+// Individual readiness check.
+type ReadinessCheck struct {
+	// Name of the readiness check.
+	Name string
+	// Function that performs the readiness check.
+	Fn ReadinessCheckFn
+	// Timeout for the readiness check (default: 5 seconds)
+	Timeout time.Duration
+}
+
+// System-generated result from an individual readiness check.
+type ReadinessCheckResult struct {
+	// Name of the readiness check.
+	Name string
+	// Status of the readiness check.
+	Status ReadinessStatus
+	// Optional message providing additional information about the readiness status.
+	Message *string
+	// Duration of the readiness check in milliseconds.
+	Duration int64
+}
+
+// System readiness status.
+type Readiness struct {
+	// Status of the service readiness. Aggregated as the worst status from
+	// all individual readiness checks. If no checks have been performed
+	// yet, the status is ReadinessStatusNotReady.
+	Status ReadinessStatus
+	// Start time of the readiness check in milliseconds since Unix epoch.
+	Start int64
+	// Duration of the readiness check in milliseconds.
+	Duration int64
+	// Individual readiness check results.
+	Details map[string]ReadinessCheckResult
+}
+
+// Performs a full system readiness check given a list of individual checks.
+func CheckReadiness(checks []ReadinessCheck) Readiness {
+	start := time.Now()
+	details := make(map[string]ReadinessCheckResult)
+	var statuses []ReadinessStatus
+
+	for _, check := range checks {
+		checkt0 := time.Now()
+		result := checkWithTimeout(check)
+		duration := time.Since(checkt0).Milliseconds()
+
+		details[check.Name] = ReadinessCheckResult{
+			Name:     check.Name,
+			Status:   result.Status,
+			Message:  result.Message,
+			Duration: duration,
+		}
+		statuses = append(statuses, result.Status)
+	}
+
+	return Readiness{
+		Status:   worstStatus(statuses),
+		Start:    start.UnixMilli(),
+		Duration: time.Since(start).Milliseconds(),
+		Details:  details,
+	}
+}
+
+// Creates a handler function for readiness HTTP requests.
+func ReadinessHandler(checks []ReadinessCheck) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		respondWithResult(w, CheckReadiness(checks))
+	}
+}
+
+// Runs a readiness check with a timeout.
+func checkWithTimeout(check ReadinessCheck) ReadinessReturn {
+	timeout := check.Timeout
+	if timeout == 0 {
+		timeout = 5 * time.Second
+	}
+
+	resultCh := make(chan ReadinessReturn, 1)
+
+	go func() {
+		resultCh <- check.Fn()
+	}()
+
+	select {
+	case result := <-resultCh:
+		return result
+	case <-time.After(timeout):
+		msg := "readiness check timed out"
+		return ReadinessReturn{
+			Status:  ReadinessStatusFatal,
+			Message: &msg,
+		}
+	}
+}
+
+func respondWithResult(w http.ResponseWriter, result Readiness) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(result.Status.HTTPStatus())
+	json.NewEncoder(w).Encode(result)
+}
+
+// ScheduledReadiness performs periodic readiness checks and stores the latest result.
+type ScheduledReadiness struct {
+	checks       []ReadinessCheck
+	interval     time.Duration
+	currentState Readiness
+	ticker       *time.Ticker
+	quit         chan struct{}
+}
+
+// NewScheduledReadiness creates a new ScheduledReadiness instance.
+func NewScheduledReadiness(checks []ReadinessCheck, interval time.Duration) *ScheduledReadiness {
+	return &ScheduledReadiness{
+		checks:   checks,
+		interval: interval,
+		quit:     make(chan struct{}),
+	}
+}
+
+// Start begins the periodic readiness checks.
+func (sr *ScheduledReadiness) Start() {
+	sr.ticker = time.NewTicker(sr.interval)
+	go func() {
+		for {
+			select {
+			case <-sr.ticker.C:
+				sr.currentState = CheckReadiness(sr.checks)
+			case <-sr.quit:
+				sr.ticker.Stop()
+				return
+			}
+		}
+	}()
+}
+
+// Stop halts the periodic readiness checks.
+func (sr *ScheduledReadiness) Stop() {
+	close(sr.quit)
+}
+
+// GetCurrentState returns the latest readiness state.
+func (sr *ScheduledReadiness) GetCurrentState() Readiness {
+	return sr.currentState
+}
+
+// Creates a handler function for scheduled readiness HTTP requests.
+func (sr *ScheduledReadiness) ReadinessHandler() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		respondWithResult(w, sr.GetCurrentState())
+	}
+}

node-health/.eslintrc.cjs

@@ -1,10 +0,0 @@
-module.exports = {
-	root: true,
-	extends: ['../../.eslintrc.cjs'],
-	parserOptions: {
-		project: './tsconfig.json',
-	},
-	rules: {
-		// package-level overrides
-	},
-};

node-health/eslint.config.mts

@@ -0,0 +1,14 @@
+import js from '@eslint/js';
+import globals from 'globals';
+import tseslint from 'typescript-eslint';
+import { defineConfig } from 'eslint/config';
+
+export default defineConfig([
+	{
+		files: ['**/*.{js,mjs,cjs,ts,mts,cts}'],
+		plugins: { js },
+		extends: ['js/recommended'],
+		languageOptions: { globals: globals.browser },
+	},
+	tseslint.configs.recommended,
+]);

node-health/package.json

@@ -1,7 +1,14 @@
 {
-	"name": "@health/node",
+	"name": "@end/node-health",
-	"version": "0.1.0",
+	"repository": {
-	"private": true,
+		"type": "git",
+		"url": "https://gitea.auvem.com/end/health.git"
+	},
+	"publishConfig": {
+		"registry": "https://gitea.auvem.com/api/packages/end/npm/"
+	},
+	"version": "0.1.2",
+	"license": "MIT",
 	"main": "dist/index.js",
 	"types": "dist/index.d.ts",
 	"files": [
@@ -14,6 +21,13 @@
 		"test": "echo \"No tests configured\" && exit 0",
 		"check": "npm run lint && npm run build"
 	},
-	"dependencies": {},
+	"devDependencies": {
-	"devDependencies": {}
+		"@eslint/js": "^9.39.2",
+		"@types/node": "^25.0.3",
+		"eslint": "^9.39.2",
+		"globals": "^16.5.0",
+		"jiti": "^2.6.1",
+		"typescript": "^5.9.3",
+		"typescript-eslint": "^8.50.1"
+	}
 }

node-health/src/checks.ts

@@ -0,0 +1,40 @@
+import { monitorEventLoopDelay } from 'node:perf_hooks';
+import { ReadinessCheck, ReadinessFunctionReturn, ReadinessStatus } from './readiness';
+
+/**
+ * Builds a readiness check function that monitors event loop lag.
+ * @param options - Configuration options for the event loop lag check.
+ * @param options.degradedMs - Threshold in milliseconds for degraded status (default: 200).
+ * @param options.failMs - Threshold in milliseconds for error status (default: 1000).
+ * @param options.histResetMs - Interval in milliseconds to reset the histogram (default: 60000).
+ * @param options.percentile - Percentile to monitor (default: 50).
+ * @returns A ReadinessFunction that checks event loop lag.
+ */
+export const buildEventLoopLagCheck = (options: {
+	degradedMs?: number;
+	failMs?: number;
+	histResetMs?: number;
+	percentile?: number;
+}): ReadinessCheck => {
+	const { degradedMs = 200, failMs = 1000, histResetMs = 60000, percentile = 50 } = options;
+
+	const hist = monitorEventLoopDelay({ resolution: 10 });
+	hist.enable();
+
+	setInterval(() => {
+		hist.reset();
+	}, histResetMs).unref();
+
+	return {
+		name: 'event-loop-lag',
+		fn: async (): Promise<ReadinessFunctionReturn> => {
+			const lag = hist.percentile(percentile) / 1e6; // Convert from nanoseconds to milliseconds
+			const status: ReadinessStatus = lag < degradedMs ? 'ok' : lag < failMs ? 'degraded' : 'error';
+			return {
+				status,
+				message: `Event loop lag is ${lag.toFixed(2)} ms`,
+			};
+		},
+		timeout: 500,
+	};
+};

node-health/src/index.ts

@@ -1,30 +1,3 @@
-/**
+export * from './liveness';
- * Simple liveness & readiness helpers
+export * from './readiness';
- */
+export * from './checks';
-
-export type ReadinessResult = {
-  ok: boolean;
-  details: { name: string; ok: boolean; error?: string }[];
-};
-
-export function liveness() {
-  return {
-    status: 'ok',
-    timestamp: Date.now(),
-  };
-}
-
-export async function readiness(
-  checks: Array<{ name: string; fn: () => Promise<boolean> | boolean }>
-): Promise<ReadinessResult> {
-  const results: ReadinessResult['details'] = [];
-  for (const c of checks) {
-    try {
-      const r = await Promise.resolve(c.fn());
-      results.push({ name: c.name, ok: !!r });
-    } catch (err: any) {
-      results.push({ name: c.name, ok: false, error: err?.message ?? String(err) });
-    }
-  }
-  return { ok: results.every((r) => r.ok), details: results };
-}

node-health/src/liveness.ts

@@ -0,0 +1,31 @@
+/**
+ * Type representing the result of a liveness check.
+ */
+export type LivenessResult = {
+	/** Status of the service (always 'ok'). */
+	status: 'ok';
+	/** Timestamp of the liveness check in milliseconds since the Unix epoch. */
+	timestamp: number;
+};
+
+/**
+ * Liveness check - indicates if the service is running.
+ * @returns A LivenessResult object.
+ */
+export function liveness() {
+	return {
+		status: 'ok',
+		timestamp: Date.now(),
+	} as LivenessResult;
+}
+
+/**
+ * Handler for liveness HTTP requests.
+ * @returns A Response object with LivenessResult in JSON format and status 200.
+ */
+export const handleLiveness = (): Response => {
+	return new Response(JSON.stringify(liveness()), {
+		status: 200,
+		headers: { 'Content-Type': 'application/json' },
+	});
+};

node-health/src/readiness.ts

@@ -0,0 +1,253 @@
+/** Readiness check function return type */
+export type ReadinessReturn = {
+	/** Status of the readiness check */
+	status: ReadinessStatus;
+	/** Optional message providing additional information about the readiness check */
+	message?: string;
+};
+
+/** Function that performs a readiness check */
+export type ReadinessCheckFn = (check: ReadinessCheck) => Promise<ReadinessReturn>;
+
+/** Status of the service readiness */
+export type ReadinessStatus = 'fatal' | 'not_ready' | 'degraded' | 'ready';
+
+/** Returns the worst readiness status from a list of statuses. */
+const worstStatus = (statuses: ReadinessStatus[]): ReadinessStatus => {
+	if (statuses.includes('fatal')) return 'fatal';
+	if (statuses.includes('not_ready')) return 'not_ready';
+	if (statuses.includes('degraded')) return 'degraded';
+	return 'ready';
+};
+
+/** Individual readiness check */
+export type ReadinessCheck = {
+	/** Name of the readiness check */
+	name: string;
+	/** Function that performs the readiness check */
+	fn: ReadinessCheckFn;
+	/** Timeout in milliseconds for the readiness check (default: 5000) */
+	timeout?: number;
+};
+
+/** System readiness status */
+export type Readiness = {
+	/**
+	 * Status of the system readiness check, aggregated as the worst status
+	 * among individual checks. If no checks have been performed yet, the status
+	 * is 'not_ready'.
+	 */
+	status: ReadinessStatus;
+	/** Start time of the system readiness check in milliseconds since the Unix epoch */
+	start: number;
+	/** Duration of the system readiness check in milliseconds */
+	duration: number;
+	/** Details of individual readiness checks */
+	details: ReadinessCheckResult[];
+};
+
+/** System-generated result from an individual readiness check */
+export type ReadinessCheckResult = {
+	/** Name of the readiness check */
+	name: string;
+	/** Status of the readiness check */
+	status: ReadinessStatus;
+	/** Duration of the readiness check in milliseconds */
+	duration: number;
+	/** Message providing additional information about the readiness check */
+	message?: string;
+};
+
+/**
+ * Performs a readiness check by executing the provided readiness functions.
+ * @param checks - An array of readiness functions to execute.
+ * @returns A Promise that resolves to a Readiness object.
+ */
+export const readiness = async (checks: ReadinessCheck[]): Promise<Readiness> => {
+	const start = Date.now();
+	const t0 = performance.now();
+	const details: ReadinessCheckResult[] = [];
+
+	for (const check of checks) {
+		const checkt0 = performance.now();
+		try {
+			const result = await withTimeout(
+				check.fn(check),
+				check.timeout ?? 5000,
+				`Readiness check '${check.name}' timed out after ${check.timeout ?? 5000} ms`,
+			);
+			details.push({
+				name: check.name,
+				status: result.status,
+				message: result.message,
+				duration: performance.now() - checkt0,
+			});
+		} catch (err) {
+			details.push({
+				name: check.name,
+				status: 'fatal',
+				message: err instanceof Error ? err.message : String(err),
+				duration: performance.now() - checkt0,
+			});
+		}
+	}
+
+	const duration = performance.now() - t0;
+
+	return {
+		status: worstStatus(details.map((d) => d.status)),
+		start,
+		duration,
+		details,
+	};
+};
+
+/**
+ * Creates a handler function for readiness HTTP requests. Warning: this runs all
+ * checks on each request and may be slow.
+ * @param checks - An array of readiness functions to execute.
+ * @returns A function that returns a Response object with Readiness in JSON format.
+ */
+export const createReadinessHandler = (checks: ReadinessCheck[]): (() => Promise<Response>) => {
+	return async () => {
+		const result = await readiness(checks);
+		return respondWithResult(result);
+	};
+};
+
+/**
+ * Class that schedules periodic readiness checks.
+ */
+export class ScheduledReadiness {
+	private checks: ReadinessCheck[];
+	private interval: number;
+	private started: boolean = false;
+	private timer: NodeJS.Timeout | null = null;
+	private latestResult: Readiness | null = null;
+	private nextResult: Promise<Readiness> | null = null;
+
+	/**
+	 * Creates an instance of ScheduledReadiness.
+	 * @param checks - An array of readiness functions to execute.
+	 * @param interval - Interval in milliseconds between readiness checks.
+	 */
+	constructor(checks: ReadinessCheck[], interval: number) {
+		this.checks = checks;
+		this.interval = interval;
+	}
+
+	/** Starts the scheduled readiness checks */
+	async start() {
+		if (this.started) return; // Already started
+		this.started = true;
+
+		const runCheck = async () => {
+			// Prevent concurrent runs
+			if (this.nextResult) return;
+
+			this.nextResult = readiness(this.checks);
+			try {
+				this.latestResult = await this.nextResult;
+			} finally {
+				this.nextResult = null;
+			}
+		};
+
+		await runCheck(); // Initial run
+		this.timer = setInterval(runCheck, this.interval);
+	}
+
+	/** Stops the scheduled readiness checks */
+	stop() {
+		if (this.timer) {
+			clearInterval(this.timer);
+			this.timer = null;
+		}
+		this.started = false;
+	}
+
+	/** Gets the next readiness result, waiting if a check is in progress */
+	async getNextResult(): Promise<Readiness | null> {
+		if (this.nextResult) {
+			return await this.nextResult;
+		}
+		return this.latestResult;
+	}
+
+	/** Gets the latest readiness result without waiting */
+	getResult(): Readiness | null {
+		return this.latestResult;
+	}
+
+	/**
+	 * Sets the interval for readiness checks and restarts the timer if already started.
+	 * @param ms - Interval in milliseconds.
+	 */
+	setInterval(ms: number) {
+		this.interval = ms;
+		if (this.timer) {
+			this.stop();
+			this.start();
+		}
+	}
+
+	/**
+	 * Creates a handler function for readiness HTTP requests using the latest scheduled result.
+	 * Scheduled handler always returns the most recent result, or 'unknown' if no checks have run yet.
+	 * @returns A function that returns a Response object with Readiness in JSON format.
+	 */
+	createHandler(): () => Promise<Response> {
+		return async () => {
+			const result = this.getResult();
+			if (!result) {
+				return new Response(
+					JSON.stringify({
+						status: 'not_ready',
+						start: Date.now(),
+						duration: 0,
+						details: [],
+					} as Readiness),
+					{
+						status: httpStatusFromReadiness('not_ready'),
+						headers: { 'Content-Type': 'application/json' },
+					},
+				);
+			}
+
+			return respondWithResult(result);
+		};
+	}
+}
+
+/** Returns a Response object with the given Readiness in JSON format */
+const respondWithResult = (result: Readiness) => {
+	return new Response(JSON.stringify(result), {
+		status: httpStatusFromReadiness(result.status),
+		headers: { 'Content-Type': 'application/json' },
+	});
+};
+
+/** Returns the HTTP status code corresponding to a given readiness status */
+const httpStatusFromReadiness = (status: ReadinessStatus): number => {
+	if (status === 'ready') return 200;
+	if (status === 'degraded') return 200; // 206 could also be suitable, but let's avoid false alarms
+	if (status === 'fatal') return 503;
+	return 200; // not_ready, treat as ok to avoid false alarms
+};
+
+const withTimeout = async <T>(
+	promise: Promise<T>,
+	ms: number,
+	timeoutMessage: string,
+): Promise<T> => {
+	let timeoutHandle: NodeJS.Timeout;
+	const timeoutPromise = new Promise<never>((_, reject) => {
+		timeoutHandle = setTimeout(() => {
+			reject(new Error(timeoutMessage));
+		}, ms);
+	});
+
+	return Promise.race([promise, timeoutPromise]).finally(() => {
+		clearTimeout(timeoutHandle);
+	});
+};

node-health/tsconfig.json

@@ -1,6 +1,16 @@
 {
-	"extends": "../tsconfig.base.json",
 	"compilerOptions": {
+		"lib": ["es2023"],
+		"target": "es2023",
+		"module": "node20",
+		"declaration": true,
+		"declarationMap": true,
+		"sourceMap": true,
+		"strict": true,
+		"esModuleInterop": true,
+		"skipLibCheck": true,
+		"forceConsistentCasingInFileNames": true,
+		"resolveJsonModule": true,
 		"rootDir": "src",
 		"outDir": "dist",
 		"composite": false

tsconfig.base.json

@@ -1,15 +0,0 @@
-{
-  "compilerOptions": {
-    "target": "ES2021",
-    "module": "ES2020",
-    "moduleResolution": "node",
-    "declaration": true,
-    "declarationMap": true,
-    "sourceMap": true,
-    "strict": true,
-    "esModuleInterop": true,
-    "skipLibCheck": true,
-    "forceConsistentCasingInFileNames": true,
-    "resolveJsonModule": true
-  }
-}