From 8119d31a36938fedb098a96a2dd96c5814fd3b9b Mon Sep 17 00:00:00 2001
From: tigattack <10629864+tigattack@users.noreply.github.com>
Date: Mon, 25 Nov 2024 15:25:00 +0000
Subject: [PATCH 1/2] feat: add health endpoint

Checks DB connection & lock status.
---
 apps/server/src/database/queries/meta.ts | 52 ++++++++++++++++++++++++
 apps/server/src/routes/index.ts          | 18 ++++++++
 2 files changed, 70 insertions(+)

diff --git a/apps/server/src/database/queries/meta.ts b/apps/server/src/database/queries/meta.ts
index ef68245..d309b14 100644
--- a/apps/server/src/database/queries/meta.ts
+++ b/apps/server/src/database/queries/meta.ts
@@ -35,3 +35,55 @@ export async function setFeatureCompatibilityVersion(version: string) {
   const admin = mongoose.connection.db.admin();
   await admin.command({ setFeatureCompatibilityVersion: version });
 }
+
+export async function getDatabaseHealth(): Promise<{
+  status: "UP" | "DOWN" | "READONLY";
+  details?: {
+    version: string;
+    uptime: number;
+    writable: boolean;
+  };
+  message?: string;
+}> {
+  if (!mongoose.connection.readyState || !mongoose.connection.db) {
+    return { status: "DOWN", message: "Database not connected" };
+  }
+
+  try {
+    const mongoInfos = await getMongoInfos();
+
+    // Fetch server status to get uptime
+    const admin = mongoose.connection.db.admin();
+    const serverStatus = await admin.command({ serverStatus: 1 });
+
+    // Check for fsyncLock using db.currentOp()
+    const currentOp = await admin.command({ currentOp: 1 });
+    const isWriteLocked = currentOp.inprog.some((op: { desc: string, active: boolean }) => op.desc === 'fsyncLockWorker' && op.active);
+
+    if (isWriteLocked) {
+      return {
+        status: "READONLY",
+        details: {
+          version: mongoInfos.version,
+          uptime: serverStatus.uptime || 0,
+          writable: false,
+        },
+        message: "Database is read-only (fsyncLock enabled)",
+      };
+    }
+
+    // If no lock is detected, check if the DB is generally writable
+    return {
+      status: "UP",
+      details: {
+        version: mongoInfos.version,
+        uptime: serverStatus.uptime || 0,
+        writable: true,
+      },
+    };
+
+  } catch (error) {
+    console.error("Error querying database health:", error);
+    return { status: "DOWN", message: "Error querying database health" };
+  }
+}
diff --git a/apps/server/src/routes/index.ts b/apps/server/src/routes/index.ts
index 5b580ad..64218e0 100644
--- a/apps/server/src/routes/index.ts
+++ b/apps/server/src/routes/index.ts
@@ -18,6 +18,7 @@ import {
   setUserPublicToken,
   storeInUser,
 } from "../database";
+import { getDatabaseHealth } from "../database/queries/meta";
 import { logger } from "../tools/logger";
 import {
   LoggedRequest,
@@ -36,6 +37,23 @@ router.get("/", (_, res) => {
   res.status(200).send("Hello !");
 });
 
+router.get("/health", async (_, res) => {
+  try {
+    const dbHealth = await getDatabaseHealth();
+
+    if (dbHealth.status === "DOWN") {
+      res.status(503).send({status: "DB connection error", db_health: dbHealth});
+    } else if (dbHealth.status === "READONLY") {
+      res.status(503).send({status: "warning", db_health: dbHealth});
+    } else {
+      res.status(200).send({status: "ok", db_health: dbHealth});
+    }
+  } catch (e) {
+    logger.error(e);
+    res.status(500).send({ status: "error", message: "Unexpected error" });
+  }
+});
+
 router.post("/logout", async (_, res) => {
   res.clearCookie("token");
   res.status(200).end();

From 87a1c8750e5758e48a2bba2ed2a4458f0e28703a Mon Sep 17 00:00:00 2001
From: tigattack <10629864+tigattack@users.noreply.github.com>
Date: Mon, 25 Nov 2024 15:27:10 +0000
Subject: [PATCH 2/2] fix: simplify health status error message

---
 apps/server/src/routes/index.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/apps/server/src/routes/index.ts b/apps/server/src/routes/index.ts
index 64218e0..9452d83 100644
--- a/apps/server/src/routes/index.ts
+++ b/apps/server/src/routes/index.ts
@@ -42,7 +42,7 @@ router.get("/health", async (_, res) => {
     const dbHealth = await getDatabaseHealth();
 
     if (dbHealth.status === "DOWN") {
-      res.status(503).send({status: "DB connection error", db_health: dbHealth});
+      res.status(503).send({status: "error", db_health: dbHealth});
     } else if (dbHealth.status === "READONLY") {
       res.status(503).send({status: "warning", db_health: dbHealth});
     } else {