Intermittent CONNECT_TIMEOUT errors that persist for minutes

Hello,

I am deploying a React Router v7 SSR app to AWS App Runner and running into issues.

Environment:

Supabase Pro plan, tried both Session mode (5432) and Transaction mode (6543)
AWS App Runner (1 instance, low traffic)
Drizzle ORM + postgres-js (porsager/postgres)
React Router v7 SSR appProblem:Getting DrizzleQueryError: write CONNECT_TIMEOUT on simple user queries. The key issue is that once it starts failing, retries don't help for several minutes. This happens somewhat randomly, even with low traffic.Error example:DrizzleQueryError: Failed query: select ... from"users" where "id" = $1 limit $2Error: write CONNECT_TIMEOUTWhat I've tried:
Session mode (port 5432) - same issue
Transaction mode (port 6543) - same issue
Retry logic with exponential backoff - doesn't help because the entire connection pool seems "stuck"Current postgres-js config:const client = postgres(process.env.DATABASE_URL!,{ max: 10, prepare: false, connect_timeout: 15, idle_timeout: 20, max_lifetime: 120, keep_alive: 30,});

Any ideas on what it could be? I've tried different postgres configurations, AppRunner max_concurrency settings, etc

Abayomi Praise Heritage•12/10/25, 6:28 AM

Hey This kind of CONNECT_TIMEOUT issue on App Runner usually points to how the serverless container manages connections rather than your Drizzle/Postgres setup itself. App Runner can aggressively freeze/idle instances, which causes postgres-js pools to hang instead of reconnecting cleanly.

A proper fix is to implement a resilient connection strategy—connection reuse, heartbeat pings, and a pool wrapper that forces fresh connections when App Runner resumes from idle. In some cases, moving to a managed PG proxy or adjusting App Runner’s concurrency/idle settings helps too.

I can diagnose your exact setup and configure a stable connection layer so your SSR app stops timing out. Let me know if you want me to help you resolve it.
@Tyler

garyaustin•12/10/25, 2:00 PM

@Tyler Make sure you do not give access to you project to anyone from this site unless you know them or have a business relationship with them. Mods and staff will never ask for access.

AAbayomi Praise Heritage Hey This kind of CONNECT_TIMEOUT issue on App Runner usually points to how the s...

TylerOP•12/10/25, 2:44 PM

Hi @Abayomi Praise Heritage, thanks for the offer! If it helps diagnose the issue, I moved the web app from AppRunner to Vercel and the issue cleared up. However, I would like to move it back to AppRunner. It being fixed on Vercel does suggest to me that it is some sort of stale/idle connection issue

This is my db config:

import { config } from "dotenv";
import { drizzle, type PostgresJsDatabase } from "drizzle-orm/postgres-js";
import postgres, { type Sql } from "postgres";
import * as schema from "./schema/index";

config({ path: "../../.env" });

// Declare global type for the singleton
declare global {
    // eslint-disable-next-line no-var
    var __db_client: Sql | undefined;
    // eslint-disable-next-line no-var
    var __db: PostgresJsDatabase<typeof schema> | undefined;
}

function getClient(): Sql {
    if (globalThis.__db_client) {
        return globalThis.__db_client;
    }

    const client = postgres(process.env.DATABASE_URL!, {
        max: 2,
        prepare: true,
        connect_timeout: 15,
        idle_timeout: 20,
        max_lifetime: 60 * 4,
    });

    globalThis.__db_client = client;
    return client;
}

function getDb(): PostgresJsDatabase<typeof schema> {
    if (globalThis.__db) {
        return globalThis.__db;
    }

    const db = drizzle({ client: getClient(), schema });
    globalThis.__db = db;
    return db;
}

export const db = getDb();

import { config } from "dotenv";
import { drizzle, type PostgresJsDatabase } from "drizzle-orm/postgres-js";
import postgres, { type Sql } from "postgres";
import * as schema from "./schema/index";

config({ path: "../../.env" });

// Declare global type for the singleton
declare global {
    // eslint-disable-next-line no-var
    var __db_client: Sql | undefined;
    // eslint-disable-next-line no-var
    var __db: PostgresJsDatabase<typeof schema> | undefined;
}

function getClient(): Sql {
    if (globalThis.__db_client) {
        return globalThis.__db_client;
    }

    const client = postgres(process.env.DATABASE_URL!, {
        max: 2,
        prepare: true,
        connect_timeout: 15,
        idle_timeout: 20,
        max_lifetime: 60 * 4,
    });

    globalThis.__db_client = client;
    return client;
}

function getDb(): PostgresJsDatabase<typeof schema> {
    if (globalThis.__db) {
        return globalThis.__db;
    }

    const db = drizzle({ client: getClient(), schema });
    globalThis.__db = db;
    return db;
}

export const db = getDb();

and then server-side, I make calls like:

import { db } from "@repo/db";
...
    const totalCount = await db
        .select({
            count: count(),
        })
        .from(table)
        .where(filters);

import { db } from "@repo/db";
...
    const totalCount = await db
        .select({
            count: count(),
        })
        .from(table)
        .where(filters);

import { config } from "dotenv"; import { drizzle, type PostgresJsDatabase } from "drizzle-orm/postgres-js"; import postgres, { type Sql } from "postgres"; import * as schema from "./schema/index"; config({ path: "../../.env" }); // Declare global type for the singleton declare global { // eslint-disable-next-line no-var var __db_client: Sql | undefined; // eslint-disable-next-line no-var var __db: PostgresJsDatabase<typeof schema> | undefined; } function getClient(): Sql { if (globalThis.__db_client) { return globalThis.__db_client; } const client = postgres(process.env.DATABASE_URL!, { max: 2, prepare: true, connect_timeout: 15, idle_timeout: 20, max_lifetime: 60 * 4, }); globalThis.__db_client = client; return client; } function getDb(): PostgresJsDatabase<typeof schema> { if (globalThis.__db) { return globalThis.__db; } const db = drizzle({ client: getClient(), schema }); globalThis.__db = db; return db; } export const db = getDb();

Intermittent CONNECT_TIMEOUT errors that persist for minutes

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