fix: use SELECT 1 for health checks #518

backend/src/app.js

@@ -19,9 +19,8 @@ import x402Router from "./routes/x402.js";
 import authRouter from "./routes/auth.js";
 
 import { requireApiKeyAuth } from "./lib/auth.js";
-import { isHorizonReachable } from "./lib/stellar.js";
-import { supabase } from "./lib/supabase.js";
 import { pool } from "./lib/db.js";
+import { probeHealth } from "./lib/health.js";
 import { x402Middleware } from "./middleware/x402.js";
 
 import { idempotencyMiddleware } from "./lib/idempotency.js";
@@ -203,18 +202,15 @@ export async function createApp({ redisClient }) {
    *                   type: string
    *                 horizon_reachable:
    *                   type: boolean
-   */
+  */
   app.get("/health", async (req, res) => {
-    const [dbResult, horizonReachable] = await Promise.allSettled([
-      supabase.from("merchants").select("id").limit(1),
-      isHorizonReachable(),
-    ]);
-
-    const dbOk = dbResult.status === "fulfilled" && !dbResult.value?.error;
-    if (!dbOk) {
-      console.error("Health DB error:", JSON.stringify(dbResult.reason || dbResult.value?.error));
+    const { database, horizon } = await probeHealth();
+
+    if (!database.ok) {
+      console.error("Health DB error:", database.error);
     }
-    const horizonOk = horizonReachable.status === "fulfilled" && horizonReachable.value === true;
+    const dbOk = database.ok;
+    const horizonOk = horizon.ok;
 
     const status = dbOk && horizonOk ? 200 : 503;
 

backend/src/index.js

@@ -13,12 +13,11 @@ import metricsRouter from "./routes/metrics.js";
 import authRouter from "./routes/auth.js";
 import auditRouter from "./routes/audit.js";
 import { requireApiKeyAuth } from "./lib/auth.js";
-import { isHorizonReachable } from "./lib/stellar.js";
-import { supabase } from "./lib/supabase.js";
 import { pool, closePool } from "./lib/db.js";
 import { validateEnvironmentVariables } from "./lib/env-validation.js";
 import { formatZodError } from "./lib/request-schemas.js";
 import { idempotencyMiddleware } from "./lib/idempotency.js";
+import { probeHealth } from "./lib/health.js";
 import { closeRedisClient, connectRedisClient } from "./lib/redis.js";
 import {
   createRedisRateLimitStore,
@@ -82,45 +81,33 @@ app.use(express.json({ limit: "1mb" }));
 app.use(morgan(":request-id :method :url :status :response-time ms"));
 
 app.get("/health", async (req, res) => {
-  try {
-    const [dbResult, horizonReachable] = await Promise.all([
-      supabase.from("merchants").select("id").limit(1),
-      isHorizonReachable(),
-    ]);
-
-    const { error } = dbResult;
-
-    if (error) {
-      return res.status(503).json({
-        ok: false,
-        service: "stellar-payment-api",
-        error: "Database unavailable",
-        horizon_reachable: horizonReachable,
-      });
-    }
-
-    if (!horizonReachable) {
-      return res.status(503).json({
-        ok: false,
-        service: "stellar-payment-api",
-        error: "Horizon unavailable",
-        horizon_reachable: false,
-      });
-    }
-
-    res.json({
-      ok: true,
+  const { database, horizon } = await probeHealth();
+
+  if (!database.ok) {
+    res.status(503).json({
+      ok: false,
       service: "stellar-payment-api",
-      horizon_reachable: true,
+      error: "Database unavailable",
+      horizon_reachable: horizon.ok,
     });
-  } catch {
+    return;
+  }
+
+  if (!horizon.ok) {
     res.status(503).json({
       ok: false,
       service: "stellar-payment-api",
-      error: "Health check failed",
+      error: "Horizon unavailable",
       horizon_reachable: false,
     });
+    return;
   }
+
+  res.json({
+    ok: true,
+    service: "stellar-payment-api",
+    horizon_reachable: true,
+  });
 });
 
 app.use("/api/create-payment", requireApiKeyAuth());

backend/src/lib/health.js

@@ -0,0 +1,20 @@
+import { pool } from "./db.js";
+import { isHorizonReachable } from "./stellar.js";
+
+export async function probeHealth({ db = pool, horizonProbe = isHorizonReachable } = {}) {
+  const [dbResult, horizonResult] = await Promise.allSettled([
+    db.query("SELECT 1"),
+    horizonProbe(),
+  ]);
+
+  return {
+    database: {
+      ok: dbResult.status === "fulfilled",
+      error: dbResult.status === "rejected" ? dbResult.reason : null,
+    },
+    horizon: {
+      ok: horizonResult.status === "fulfilled" && horizonResult.value === true,
+      error: horizonResult.status === "rejected" ? horizonResult.reason : null,
+    },
+  };
+}

backend/src/lib/health.test.js

@@ -0,0 +1,45 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const query = vi.fn();
+const isHorizonReachable = vi.fn();
+
+vi.mock("./db.js", () => ({
+  pool: { query },
+}));
+
+vi.mock("./stellar.js", () => ({
+  isHorizonReachable,
+}));
+
+describe("probeHealth", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('runs a "SELECT 1" database probe and reports both services healthy', async () => {
+    query.mockResolvedValue({ rows: [{ "?column?": 1 }] });
+    isHorizonReachable.mockResolvedValue(true);
+
+    const { probeHealth } = await import("./health.js");
+    const result = await probeHealth();
+
+    expect(query).toHaveBeenCalledWith("SELECT 1");
+    expect(isHorizonReachable).toHaveBeenCalledTimes(1);
+    expect(result).toEqual({
+      database: { ok: true, error: null },
+      horizon: { ok: true, error: null },
+    });
+  });
+
+  it("reports the database as unavailable when the SELECT 1 query fails", async () => {
+    const dbError = new Error("db down");
+    query.mockRejectedValue(dbError);
+    isHorizonReachable.mockResolvedValue(true);
+
+    const { probeHealth } = await import("./health.js");
+    const result = await probeHealth();
+
+    expect(result.database).toEqual({ ok: false, error: dbError });
+    expect(result.horizon).toEqual({ ok: true, error: null });
+  });
+});

backend/tests/integration/health.test.js

@@ -18,6 +18,13 @@ vi.mock("../../src/lib/stellar.js", () => ({
   isHorizonReachable: vi.fn(async () => true),
 }));
 
+vi.mock("../../src/lib/health.js", () => ({
+  probeHealth: vi.fn(async () => ({
+    database: { ok: true, error: null },
+    horizon: { ok: true, error: null },
+  })),
+}));
+
 vi.mock("../../src/lib/supabase.js", () => {
   return {
     supabase: {