ClickHouse Deploy Integration

Overview

Deploy applications that connect to ClickHouse Cloud from serverless and container platforms with proper connection management and secrets handling. The same platform-agnostic connection module drives all three targets — Vercel, Fly.io, and Cloud Run — so only the secrets mechanism and runtime model change per platform.

Prerequisites

ClickHouse Cloud instance (or self-hosted with public endpoint)
Platform CLI installed (vercel, fly, or gcloud)
Application tested locally against ClickHouse

Instructions

Step 1: ClickHouse Connection Module (Platform-Agnostic)

Write a singleton client so a serverless cold start reuses one connection instead of opening a new pool per invocation. Keep max_open_connections low for serverless and enable compression to cut egress.

// src/db.ts — singleton for serverless-safe connections
import { createClient, ClickHouseClient } from '@clickhouse/client';

let client: ClickHouseClient | null = null;

export function getClickHouse(): ClickHouseClient {
  if (!client) {
    client = createClient({
      url: process.env.CLICKHOUSE_HOST!,         // https://<host>:8443
      username: process.env.CLICKHOUSE_USER!,
      password: process.env.CLICKHOUSE_PASSWORD!,
      database: process.env.CLICKHOUSE_DATABASE ?? 'default',
      request_timeout: 30_000,
      max_open_connections: 5,    // Low for serverless (many cold starts)
      compression: {
        request: true,            // Saves egress bandwidth
        response: true,
      },
    });
  }
  return client;
}

Step 2: Pick a platform and deploy

Choose the target that matches your runtime model, then set secrets and deploy. All three import the getClickHouse() module above unchanged.

Vercel (serverless functions) — vercel env add per secret; best for API endpoints. Keep max_open_connections at 1-3.
Fly.io (containers) — fly secrets set + a fly.toml health check; best for long-running apps with persistent connections.
Cloud Run (containers) — secrets via Secret Manager (--set-secrets); best for event-driven workloads. Set --min-instances=1 to avoid cold-start connection churn.

Full per-platform commands, the Next.js App Router query example, fly.toml, the Cloud Run deploy script, and a platform comparison table: Platform deployment walkthrough.

Step 3: Add health check and graceful shutdown

Expose a /health endpoint that pings ClickHouse (drives Fly.io / Cloud Run readiness probes) and close the client on SIGTERM/SIGINT so pending inserts flush before the container is recycled. Full code: Production patterns.

Output

Running this skill produces a deployable ClickHouse-connected application:

src/db.ts — a singleton ClickHouse client, serverless-safe and compressed.
Platform config with secrets set: Vercel env vars, fly.toml + fly secrets, or a Cloud Run service wired to Secret Manager.
A /health endpoint reporting { status, clickhouse: { connected, latencyMs } }.
Graceful-shutdown handlers that flush pending inserts on SIGTERM/SIGINT.
A live deployment reachable over HTTPS on the chosen platform.

Error Handling

Issue	Cause	Solution
`ECONNRESET` on Vercel	Function timeout	Reduce query scope, increase timeout
`TLS handshake` failed	Wrong port	Use port 8443 for Cloud
Secret not found	Env var not set	Check platform secret config
Cold start latency	New connection per invocation	Use `min-instances=1` on Cloud Run

Examples

Deploy an analytics API to Vercel: set the four CLICKHOUSE_* secrets with vercel env add, drop the getClickHouse() module in src/db.ts, and add a route that runs a parameterized SELECT ... GROUP BY event_type. See the full Next.js App Router handler under the Vercel section of the Platform deployment walkthrough.

Deploy a long-running container to Fly.io: add a [[http_service.checks]] block pointing at /health, fly secrets set the ClickHouse credentials, then fly deploy — see the complete fly.toml in the Platform deployment walkthrough.

Deploy an event-driven service to Cloud Run: store host + password in Secret Manager, wire them with --set-secrets, and set --min-instances=1. Full deploy script in the Platform deployment walkthrough.

Resources

Next Steps

For data ingestion patterns, see clickhouse-webhooks-events.