node: breaking naming changes to match go version

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/src/readiness.ts

@@ -1,5 +1,5 @@
-/** Return type of a readiness check function */
-export type ReadinessFunctionReturn = {
+/** Readiness check function return type */
+export type ReadinessReturn = {
 	/** Status of the readiness check */
 	status: ReadinessStatus;
 	/** Optional message providing additional information about the readiness check */
@@ -7,45 +7,47 @@ export type ReadinessFunctionReturn = {
 };
 
 /** Function that performs a readiness check */
-export type ReadinessFunction = (check: ReadinessCheck) => Promise<ReadinessFunctionReturn>;
+export type ReadinessCheckFn = (check: ReadinessCheck) => Promise<ReadinessReturn>;
 
-/** Status of a readiness check */
-export type ReadinessStatus = 'ok' | 'error' | 'degraded';
+/** Status of the service readiness */
+export type ReadinessStatus = 'fatal' | 'not_ready' | 'degraded' | 'ready';
 
-const aggregateStatus = (statuses: ReadinessStatus[]): ReadinessStatus => {
-	if (statuses.includes('error')) return 'error';
+/** 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 'ok';
+	return 'ready';
 };
 
-/** Represents a readiness check with an optional timeout */
+/** Individual readiness check */
 export type ReadinessCheck = {
 	/** Name of the readiness check */
 	name: string;
 	/** Function that performs the readiness check */
-	fn: ReadinessFunction;
+	fn: ReadinessCheckFn;
 	/** Timeout in milliseconds for the readiness check (default: 5000) */
 	timeout?: number;
 };
 
-/** Result of a system readiness check */
-export type ReadinessResult = {
+/** System readiness status */
+export type Readiness = {
 	/**
 	 * Status of the system readiness check, aggregated as the worst status
-	 * among individual checks. 'unknown' is a special case indicating that
-	 * no checks were performed, used by ScheduledReadiness before the first run.
-	 * */
-	status: ReadinessStatus | 'unknown';
+	 * 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: ReadinessDetail[];
+	details: ReadinessCheckResult[];
 };
 
-/** Detail of an individual readiness check */
-export type ReadinessDetail = {
+/** System-generated result from an individual readiness check */
+export type ReadinessCheckResult = {
 	/** Name of the readiness check */
 	name: string;
 	/** Status of the readiness check */
@@ -59,12 +61,12 @@ export type ReadinessDetail = {
 /**
  * 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 ReadinessResult object.
+ * @returns A Promise that resolves to a Readiness object.
  */
-export const readiness = async (checks: ReadinessCheck[]): Promise<ReadinessResult> => {
+export const readiness = async (checks: ReadinessCheck[]): Promise<Readiness> => {
 	const start = Date.now();
 	const t0 = performance.now();
-	const details: ReadinessDetail[] = [];
+	const details: ReadinessCheckResult[] = [];
 
 	for (const check of checks) {
 		const checkt0 = performance.now();
@@ -83,7 +85,7 @@ export const readiness = async (checks: ReadinessCheck[]): Promise<ReadinessResu
 		} catch (err) {
 			details.push({
 				name: check.name,
-				status: 'error',
+				status: 'fatal',
 				message: err instanceof Error ? err.message : String(err),
 				duration: performance.now() - checkt0,
 			});
@@ -93,7 +95,7 @@ export const readiness = async (checks: ReadinessCheck[]): Promise<ReadinessResu
 	const duration = performance.now() - t0;
 
 	return {
-		status: aggregateStatus(details.map((d) => d.status)),
+		status: worstStatus(details.map((d) => d.status)),
 		start,
 		duration,
 		details,
@@ -104,7 +106,7 @@ export const readiness = async (checks: ReadinessCheck[]): Promise<ReadinessResu
  * 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 ReadinessResult in JSON format.
+ * @returns A function that returns a Response object with Readiness in JSON format.
  */
 export const createReadinessHandler = (checks: ReadinessCheck[]): (() => Promise<Response>) => {
 	return async () => {
@@ -121,8 +123,8 @@ export class ScheduledReadiness {
 	private interval: number;
 	private started: boolean = false;
 	private timer: NodeJS.Timeout | null = null;
-	private latestResult: ReadinessResult | null = null;
-	private nextResult: Promise<ReadinessResult> | null = null;
+	private latestResult: Readiness | null = null;
+	private nextResult: Promise<Readiness> | null = null;
 
 	/**
 	 * Creates an instance of ScheduledReadiness.
@@ -165,7 +167,7 @@ export class ScheduledReadiness {
 	}
 
 	/** Gets the next readiness result, waiting if a check is in progress */
-	async getNextResult(): Promise<ReadinessResult | null> {
+	async getNextResult(): Promise<Readiness | null> {
 		if (this.nextResult) {
 			return await this.nextResult;
 		}
@@ -173,7 +175,7 @@ export class ScheduledReadiness {
 	}
 
 	/** Gets the latest readiness result without waiting */
-	getResult(): ReadinessResult | null {
+	getResult(): Readiness | null {
 		return this.latestResult;
 	}
 
@@ -192,7 +194,7 @@ export class ScheduledReadiness {
 	/**
 	 * 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 ReadinessResult in JSON format.
+	 * @returns A function that returns a Response object with Readiness in JSON format.
 	 */
 	createHandler(): () => Promise<Response> {
 		return async () => {
@@ -200,13 +202,13 @@ export class ScheduledReadiness {
 			if (!result) {
 				return new Response(
 					JSON.stringify({
-						status: 'unknown',
+						status: 'not_ready',
 						start: Date.now(),
 						duration: 0,
 						details: [],
-					} as ReadinessResult),
+					} as Readiness),
 					{
-						status: httpStatusFromReadiness('unknown'),
+						status: httpStatusFromReadiness('not_ready'),
 						headers: { 'Content-Type': 'application/json' },
 					},
 				);
@@ -217,8 +219,8 @@ export class ScheduledReadiness {
 	}
 }
 
-/** Returns a Response object with the given ReadinessResult in JSON format */
-const respondWithResult = (result: ReadinessResult) => {
+/** 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' },
@@ -226,11 +228,11 @@ const respondWithResult = (result: ReadinessResult) => {
 };
 
 /** Returns the HTTP status code corresponding to a given readiness status */
-const httpStatusFromReadiness = (status: ReadinessStatus | 'unknown'): number => {
-	if (status === 'ok') return 200;
+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 === 'error') return 503;
-	return 200; // unknown, treat as ok to avoid false alarms
+	if (status === 'fatal') return 503;
+	return 200; // not_ready, treat as ok to avoid false alarms
 };
 
 const withTimeout = async <T>(