tessl install github:jezweb/claude-skills --skill cloudflare-hyperdrivegithub.com/jezweb/claude-skills
Connect Workers to PostgreSQL/MySQL with Hyperdrive's global pooling and caching. Use when: connecting to existing databases, setting up connection pools, using node-postgres/mysql2, integrating Drizzle/Prisma, or troubleshooting pool acquisition failures, TLS errors, or nodejs_compat missing. Prevents 11 documented errors.
Review Score
87%
Validation Score
12/16
Implementation Score
77%
Activation Score
100%
Status: Production Ready ✅ Last Updated: 2026-01-09 Dependencies: cloudflare-worker-base (recommended for Worker setup) Latest Versions: wrangler@4.58.0, pg@8.16.3+ (minimum), postgres@3.4.8, mysql2@3.16.0
Recent Updates (2025):
# For PostgreSQL
npx wrangler hyperdrive create my-postgres-db \
--connection-string="postgres://user:password@db-host.cloud:5432/database"
# For MySQL
npx wrangler hyperdrive create my-mysql-db \
--connection-string="mysql://user:password@db-host.cloud:3306/database"
# Output:
# ✅ Successfully created Hyperdrive configuration
#
# [[hyperdrive]]
# binding = "HYPERDRIVE"
# id = "a76a99bc-7901-48c9-9c15-c4b11b559606"Save the id value - you'll need it in the next step!
Add to your wrangler.jsonc:
{
"name": "my-worker",
"main": "src/index.ts",
"compatibility_date": "2024-09-23",
"compatibility_flags": ["nodejs_compat"], // REQUIRED for database drivers
"hyperdrive": [
{
"binding": "HYPERDRIVE", // Available as env.HYPERDRIVE
"id": "a76a99bc-7901-48c9-9c15-c4b11b559606" // From wrangler hyperdrive create
}
]
}CRITICAL:
nodejs_compat flag is REQUIRED for all database driversbinding is how you access Hyperdrive in code (env.HYPERDRIVE)id is the Hyperdrive configuration ID (NOT your database ID)# For PostgreSQL (choose one)
npm install pg # node-postgres (most common)
npm install postgres # postgres.js (modern, minimum v3.4.5)
# For MySQL
npm install mysql2 # mysql2 (minimum v3.13.0)PostgreSQL with node-postgres (pg):
import { Client } from "pg";
type Bindings = {
HYPERDRIVE: Hyperdrive;
};
export default {
async fetch(request: Request, env: Bindings, ctx: ExecutionContext) {
const client = new Client({
connectionString: env.HYPERDRIVE.connectionString
});
await client.connect();
try {
const result = await client.query('SELECT * FROM users LIMIT 10');
return Response.json({ users: result.rows });
} finally {
// Clean up connection AFTER response is sent
ctx.waitUntil(client.end());
}
}
};MySQL with mysql2:
import { createConnection } from "mysql2/promise";
export default {
async fetch(request: Request, env: Bindings, ctx: ExecutionContext) {
const connection = await createConnection({
host: env.HYPERDRIVE.host,
user: env.HYPERDRIVE.user,
password: env.HYPERDRIVE.password,
database: env.HYPERDRIVE.database,
port: env.HYPERDRIVE.port,
disableEval: true // REQUIRED for Workers (eval() not supported)
});
try {
const [rows] = await connection.query('SELECT * FROM users LIMIT 10');
return Response.json({ users: rows });
} finally {
ctx.waitUntil(connection.end());
}
}
};npx wrangler deployThat's it! Your Worker now connects to your existing database via Hyperdrive with:
This skill prevents 11 documented issues with sources and solutions.
Error: Connection fails with hostname like xxx.hyperdrive.local
Source: GitHub Issue #11556
Platforms: Windows, macOS 26 Tahoe, Ubuntu 24.04 LTS (wrangler@4.54.0+)
Why It Happens: Hyperdrive local proxy hostname fails to resolve on certain platforms
Prevention:
Use environment variable for local development:
export CLOUDFLARE_HYPERDRIVE_LOCAL_CONNECTION_STRING_HYPERDRIVE="postgres://user:password@localhost:5432/db"
npx wrangler devOr use wrangler dev --remote (caution: uses production database)
Status: Open issue, workaround available
Error: Connection hangs indefinitely with no error message Source: GitHub Issue #6179 Why It Happens: Using IP address instead of hostname in connection string causes postgres.js to hang Prevention:
// ❌ WRONG - IP address causes indefinite hang
const connection = "postgres://user:password@192.168.1.100:5432/db"
// ✅ CORRECT - Use hostname
const connection = "postgres://user:password@db.example.com:5432/db"Additional Gotcha: Miniflare (local dev) only supports A-z0-9 characters in passwords, despite Postgres allowing special characters. Use simple passwords for local development.
Error: "unsupported authentication method" Source: GitHub Issue #10617 Why It Happens: MySQL 8.0.43+ introduces new authentication method not supported by Hyperdrive Prevention:
Use MySQL 8.0.40 or earlier, or configure user to use supported auth plugin:
ALTER USER 'username'@'%' IDENTIFIED WITH caching_sha2_password BY 'password';Supported Auth Plugins: Only caching_sha2_password and mysql_native_password
Status: Known issue tracked as CFSQL-1392
Error: SSL required but connection fails in local development Source: GitHub Issue #10124 Why It Happens: Hyperdrive local mode doesn't support SSL connections to remote databases (e.g., Neon, cloud providers) Prevention:
Use conditional connection in code:
const url = env.isLocal ? env.DB_URL : env.HYPERDRIVE.connectionString;
const client = postgres(url, {
fetch_types: false,
max: 2,
});Alternative: Use wrangler dev --remote (⚠️ connects to production database)
Timeline: SSL support planned for 2026 (requires workerd/Workers runtime changes, tracked as SQC-645)
Error: SET statements don't persist across queries Source: Cloudflare Hyperdrive Docs - How Hyperdrive Works Why It Happens: Hyperdrive operates in transaction mode where connections are returned to pool after each transaction and RESET Prevention:
// ❌ WRONG - SET won't persist across queries
await client.query('SET search_path TO myschema');
await client.query('SELECT * FROM mytable'); // Uses default search_path!
// ✅ CORRECT - SET within transaction
await client.query('BEGIN');
await client.query('SET search_path TO myschema');
await client.query('SELECT * FROM mytable'); // Now uses myschema
await client.query('COMMIT');⚠️ WARNING: Wrapping multiple operations in a single transaction to maintain SET state will affect Hyperdrive's performance and scaling.
Error: Worker hangs and times out after first request Source: GitHub Issue #28193 Verified: Multiple users confirmed Why It Happens: Prisma's connection pool attempts to reuse connections across request contexts, violating Workers' I/O isolation Prevention:
// ❌ WRONG - Global Prisma client reused across requests
const prisma = new PrismaClient({ adapter });
export default {
async fetch(request: Request, env: Bindings) {
// First request: works
// Subsequent requests: hang indefinitely
const users = await prisma.user.findMany();
return Response.json({ users });
}
};
// ✅ CORRECT - Create new client per request
export default {
async fetch(request: Request, env: Bindings, ctx: ExecutionContext) {
const pool = new Pool({
connectionString: env.HYPERDRIVE.connectionString,
max: 5
});
const adapter = new PrismaPg(pool);
const prisma = new PrismaClient({ adapter });
try {
const users = await prisma.user.findMany();
return Response.json({ users });
} finally {
ctx.waitUntil(pool.end());
}
}
};Error: Hyperdrive provides no benefit with Neon serverless driver Source: Neon GitHub Repo, Cloudflare Docs Why It Happens: Neon's serverless driver uses WebSockets instead of TCP, bypassing Hyperdrive's connection pooling Prevention:
// ❌ WRONG - Neon serverless driver bypasses Hyperdrive
import { neon } from '@neondatabase/serverless';
const sql = neon(env.HYPERDRIVE.connectionString);
// This uses WebSockets, not TCP - Hyperdrive doesn't help
// ✅ CORRECT - Use traditional TCP driver with Hyperdrive
import postgres from 'postgres';
const sql = postgres(env.HYPERDRIVE.connectionString, {
prepare: true,
max: 5
});Official Recommendation: Neon documentation states "On Cloudflare Workers, consider using Cloudflare Hyperdrive instead of this driver"
Error: Double-pooling causes connection issues Source: Cloudflare Docs - Supabase Why It Happens: Using Supabase pooled connection (Supavisor) creates double-pooling; Supavisor doesn't support prepared statements Prevention:
# ❌ WRONG - Using Supabase pooled connection (Supavisor)
npx wrangler hyperdrive create my-supabase \
--connection-string="postgres://user:password@aws-0-us-west-1.pooler.supabase.com:6543/postgres"
# ✅ CORRECT - Use Supabase direct connection
npx wrangler hyperdrive create my-supabase \
--connection-string="postgres://user:password@db.projectref.supabase.co:5432/postgres"Reason: Hyperdrive provides its own pooling; double-pooling causes issues and breaks caching
Error: 500 errors approximately 95% of the time
Source: GitHub Issue #3893
Verified: Reproduced by multiple users
Why It Happens: Nitro 3's built-in useDatabase (db0/integrations/drizzle) has I/O isolation issues
Prevention:
// ❌ WRONG - Nitro's useDatabase fails ~95% of the time
import { useDatabase } from 'db0';
import { drizzle } from 'db0/integrations/drizzle';
export default eventHandler(async () => {
const db = useDatabase();
const users = await drizzle(db).select().from(usersTable);
// Fails ~95% of the time with 500 error
});
// ✅ CORRECT - Create Drizzle client directly
import postgres from 'postgres';
import { drizzle } from 'drizzle-orm/postgres-js';
export default eventHandler(async (event) => {
const sql = postgres(event.context.cloudflare.env.HYPERDRIVE.connectionString, {
max: 5,
prepare: true
});
const db = drizzle(sql);
const users = await db.select().from(usersTable);
event.context.cloudflare.ctx.waitUntil(sql.end());
return { users };
});Error Message: "Cannot perform I/O on behalf of a different request"
Error: Prepared statement caching doesn't work properly Source: Cloudflare Docs Why It Happens: postgres.js versions before 3.4.5 don't support Hyperdrive's prepared statement caching properly Prevention:
# Minimum version for Hyperdrive compatibility
npm install postgres@3.4.5
# Current recommended version
npm install postgres@3.4.8Related: May 2025 prepared statement caching improvements require minimum version 3.4.5
Error: Hyperdrive provides no benefit or causes connection issues Source: General pattern from Neon serverless driver issue Why It Happens: Hyperdrive requires TCP connections; WebSocket-based drivers bypass the TCP pooling layer Prevention:
Use traditional TCP-based drivers (pg, postgres.js, mysql2) instead of WebSocket-based drivers.
Affected Drivers: Any database driver using WebSockets instead of TCP
Hyperdrive eliminates 7 connection round trips (TCP + TLS + auth) by:
Result: Single-region databases feel globally distributed.
# PostgreSQL
postgres://user:password@host:5432/database
postgres://user:password@host:5432/database?sslmode=require
# MySQL
mysql://user:password@host:3306/database
# URL-encode special chars: p@ssw$rd → p%40ssw%24rdconst client = new Client({ connectionString: env.HYPERDRIVE.connectionString });
await client.connect();
const result = await client.query('SELECT ...');
ctx.waitUntil(client.end()); // CRITICAL: Non-blocking cleanupUse for: Simple queries, single query per request
const pool = new Pool({
connectionString: env.HYPERDRIVE.connectionString,
max: 5 // CRITICAL: Workers limit is 6 connections (July 2025: configurable ~20 Free, ~100 Paid)
});
const [result1, result2] = await Promise.all([
pool.query('SELECT ...'),
pool.query('SELECT ...')
]);
ctx.waitUntil(pool.end());Use for: Parallel queries in single request
ALWAYS use ctx.waitUntil(client.end()) - non-blocking cleanup after response sent
NEVER use await client.end() - blocks response, adds latency
import { drizzle } from "drizzle-orm/postgres-js";
import postgres from "postgres";
const sql = postgres(env.HYPERDRIVE.connectionString, { max: 5 });
const db = drizzle(sql);
const allUsers = await db.select().from(users);
ctx.waitUntil(sql.end());⚠️ CRITICAL: Do NOT reuse Prisma client across requests in Workers. Create new client per request.
import { PrismaPg } from "@prisma/adapter-pg";
import { PrismaClient } from "@prisma/client";
import { Pool } from "pg";
// ❌ WRONG - Global client causes hangs after first request
const prisma = new PrismaClient({ adapter });
export default {
async fetch(request: Request, env: Bindings) {
const users = await prisma.user.findMany(); // Hangs after first request
return Response.json({ users });
}
};
// ✅ CORRECT - Per-request client
export default {
async fetch(request: Request, env: Bindings, ctx: ExecutionContext) {
const pool = new Pool({ connectionString: env.HYPERDRIVE.connectionString, max: 5 });
const adapter = new PrismaPg(pool);
const prisma = new PrismaClient({ adapter });
try {
const users = await prisma.user.findMany();
return Response.json({ users });
} finally {
ctx.waitUntil(pool.end());
}
}
};Why: Prisma's connection pool attempts to reuse connections across request contexts, violating Workers' I/O isolation. Source: GitHub Issue #28193
Note: Prisma requires driver adapters (@prisma/adapter-pg).
Important: Local Hyperdrive connections do NOT support SSL. This affects databases that require SSL (e.g., Neon, most cloud providers).
Workaround - Conditional Connection:
const url = env.isLocal ? env.DB_URL : env.HYPERDRIVE.connectionString;
const client = postgres(url, {
fetch_types: false,
max: 2,
});Alternative: Use wrangler dev --remote (⚠️ connects to production database)
Timeline: SSL support planned for 2026 (requires workerd/Workers runtime changes) Source: GitHub Issue #10124, tracked as SQC-645
Option 1: Environment Variable (Recommended)
export CLOUDFLARE_HYPERDRIVE_LOCAL_CONNECTION_STRING_HYPERDRIVE="postgres://user:password@localhost:5432/local_db"
npx wrangler devSafe to commit config, no credentials in wrangler.jsonc.
Option 2: localConnectionString in wrangler.jsonc
{ "hyperdrive": [{ "binding": "HYPERDRIVE", "id": "prod-id", "localConnectionString": "postgres://..." }] }⚠️ Don't commit credentials to version control.
Option 3: Remote Development
npx wrangler dev --remote # ⚠️ Uses PRODUCTION databaseCached: SELECT (non-mutating queries) NOT Cached: INSERT, UPDATE, DELETE, volatile functions (LASTVAL, LAST_INSERT_ID)
May 2025: 5x faster cache hits via regional prepared statement caching.
Critical for postgres.js:
const sql = postgres(env.HYPERDRIVE.connectionString, {
prepare: true // REQUIRED for caching
});Check cache status:
response.headers.get('cf-cache-status'); // HIT, MISS, BYPASS, EXPIREDSSL Modes: require (default), verify-ca (verify CA), verify-full (verify CA + hostname)
Server Certificates (verify-ca/verify-full):
npx wrangler cert upload certificate-authority --ca-cert root-ca.pem --name my-ca-cert
npx wrangler hyperdrive create my-db --connection-string="postgres://..." --ca-certificate-id <ID> --sslmode verify-fullClient Certificates (mTLS):
npx wrangler cert upload mtls-certificate --cert client-cert.pem --key client-key.pem --name my-cert
npx wrangler hyperdrive create my-db --connection-string="postgres://..." --mtls-certificate-id <ID>Connect to databases in private networks (VPCs, on-premises):
# 1. Install cloudflared (macOS: brew install cloudflare/cloudflare/cloudflared)
# 2. Create tunnel
cloudflared tunnel create my-db-tunnel
# 3. Configure config.yml
# tunnel: <TUNNEL_ID>
# ingress:
# - hostname: db.example.com
# service: tcp://localhost:5432
# 4. Run tunnel
cloudflared tunnel run my-db-tunnel
# 5. Create Hyperdrive
npx wrangler hyperdrive create my-private-db --connection-string="postgres://user:password@db.example.com:5432/database"✅ Include nodejs_compat in compatibility_flags
✅ Use ctx.waitUntil(client.end()) for connection cleanup
✅ Set max: 5 for connection pools (Workers limit: 6)
✅ Enable TLS/SSL on your database (Hyperdrive requires it)
✅ Use prepared statements for caching (postgres.js: prepare: true)
✅ Set disableEval: true for mysql2 driver
✅ Handle errors gracefully with try/catch
✅ Use environment variables for local development connection strings
✅ Test locally with wrangler dev before deploying
❌ Skip nodejs_compat flag (causes "No such module" errors)
❌ Use private IP addresses directly (use Cloudflare Tunnel instead)
❌ Use await client.end() (blocks response, use ctx.waitUntil())
❌ Set connection pool max > 5 (exceeds Workers' 6 connection limit)
❌ Wrap all queries in transactions (limits connection multiplexing)
❌ Use SQL-level PREPARE/EXECUTE/DEALLOCATE (unsupported)
❌ Use advisory locks, LISTEN/NOTIFY (PostgreSQL unsupported features)
❌ Use multi-statement queries in MySQL (unsupported)
❌ Commit database credentials to version control
❌ Use IP addresses in connection strings instead of hostnames (causes postgres.js to hang)
❌ Use Neon serverless driver with Hyperdrive (uses WebSockets, bypasses pooling)
❌ Use Supabase pooled connection string (Supavisor) with Hyperdrive (double-pooling)
❌ Reuse Prisma client instances across requests in Workers (causes hangs and timeouts)
❌ Use Nitro 3's useDatabase with Drizzle and Hyperdrive (~95% failure rate)
❌ Expect SET statements to persist across queries (transaction mode resets connections)
❌ Use postgres.js versions before 3.4.5 (breaks prepared statement caching)
# Create Hyperdrive configuration
wrangler hyperdrive create <name> --connection-string="postgres://..."
# List all Hyperdrive configurations
wrangler hyperdrive list
# Get details of a configuration
wrangler hyperdrive get <hyperdrive-id>
# Update connection string
wrangler hyperdrive update <hyperdrive-id> --connection-string="postgres://..."
# Delete configuration
wrangler hyperdrive delete <hyperdrive-id>
# Upload CA certificate
wrangler cert upload certificate-authority --ca-cert <file>.pem --name <name>
# Upload client certificate pair
wrangler cert upload mtls-certificate --cert <cert>.pem --key <key>.pem --name <name>PostgreSQL (v9.0-17.x): AWS RDS/Aurora, Google Cloud SQL, Azure, Neon, Supabase, PlanetScale, Timescale, CockroachDB, Materialize, Fly.io, pgEdge, Prisma Postgres
MySQL (v5.7-8.x): AWS RDS/Aurora, Google Cloud SQL, Azure, PlanetScale, MariaDB (April 2025 GA)
NOT Supported: SQL Server, MongoDB, Oracle
PREPARE, EXECUTE, DEALLOCATE)LISTEN and NOTIFYUSE statementsCOM_STMT_PREPARE)COM_INIT_DB messagescaching_sha2_password or mysql_native_passwordWorkaround: For unsupported features, create a second direct client connection (without Hyperdrive).
prepare: true)See references/troubleshooting.md for complete error reference with solutions.
Quick fixes:
| Error | Solution |
|---|---|
| "No such module 'node:*'" | Add nodejs_compat to compatibility_flags |
| "TLS not supported by database" | Enable SSL/TLS on your database |
| "Connection refused" | Check firewall rules, allow public internet or use Tunnel |
| "Failed to acquire connection" | Use ctx.waitUntil() for cleanup, avoid long transactions |
| "Code generation from strings disallowed" | Set disableEval: true in mysql2 config |
| "Bad hostname" | Verify DNS resolves, check for typos |
| "Invalid database credentials" | Check username/password (case-sensitive) |
Hyperdrive Dashboard → Select config → Metrics tab
Available: Query count, cache hit ratio, query latency (p50/p95/p99), connection latency, query/result bytes, error rate
# Option 1: Create new config (zero downtime)
wrangler hyperdrive create my-db-v2 --connection-string="postgres://new-creds..."
# Update wrangler.jsonc, deploy, delete old config
# Option 2: Update existing
wrangler hyperdrive update <id> --connection-string="postgres://new-creds..."Best practice: Separate configs for staging/production.
Last verified: 2026-01-21 | Skill version: 3.0.0 | Changes: Added 11 Known Issues Prevention entries (6 TIER 1, 5 TIER 2), expanded Prisma/Local Dev/Performance sections with critical warnings, updated Never Do rules
Package Versions: wrangler@4.58.0, pg@8.16.3+ (minimum), postgres@3.4.5+ (minimum for caching), postgres@3.4.8 (recommended), mysql2@3.16.0 Production Tested: Based on official Cloudflare documentation and community examples