feat: add webhooks via Cloudflare Queues and Cron Triggers

[ephraimduncan]

Summary

Adds form webhooks — when a submission arrives, formbase POSTs it to a user-configured URL with retries — built entirely on Cloudflare-native primitives. This replaces the approach in #121 (BullMQ + Redis + a separately deployed Fly.io worker), which required an always-on external service.

• Cloudflare Queues handle delivery, retry/backoff, and a dead-letter queue.
• Cloudflare Cron Triggers run a safety-net sweep (re-drives stuck deliveries) and daily log cleanup.
• No Redis, no BullMQ, no separate service.

How it works

POST /api/s/[id] / form.testWebhook
  → insert webhook_delivery_logs row (pending)
  → after() → WEBHOOK_QUEUE.send({ deliveryLogId, webhookUrl })   (deferred, never a floating promise)
        → worker.ts queue(): deliver via fetch + HMAC sign → mark success / retry w/ backoff
        → exhausted → DLQ → mark failed
  worker.ts scheduled(): */5 sweep stuck rows · 0 3 cleanup logs >90d

The custom OpenNext worker entry (apps/web/worker.ts) re-exports the generated fetch handler + cache DOs and adds queue()/scheduled(). It hydrates process.env from the bindings before dynamically importing the consumer/scheduled modules, so the workerd handlers can reach the validated env (which next dev's request context normally provides).

What's better than #121

• HMAC signing (was unsigned): WebCrypto HMAC-SHA256 over timestamp.body, sent as X-Formbase-Signature / X-Formbase-Event / X-Formbase-Timestamp, with a per-form webhook_secret.
• No floating promise: enqueue is deferred with after() (the pattern that caused the submission hang fixed in fix: prevent submission endpoint hang on Cloudflare Workers #141), not void promise.
• SSRF-hardened URL validation: production requires public HTTPS and rejects localhost/private ranges.
• Delivery visibility: a read-only "Recent deliveries" list + signing-secret field in form settings (the webhook_delivery_logs table in feat: add webhook queue system and worker #121 was never surfaced).
• Idempotency: at-least-once delivery with skip-on-success; submission id is a stable idempotency key for receivers.
• The signing secret is never exposed through the public getFormById procedure (explicit column allowlist).
• The cron sweep atomically leases stuck rows (UPDATE … SET next_retry_at … RETURNING) so it can't double-deliver rows still in the queue's own retry window.

Changes

• schema: webhook_delivery_logs table; forms.enable_webhook / webhook_url / webhook_secret; migration 0003_awesome_inhumans.
• packages/api/lib/webhook.ts: pure, runtime-agnostic payload/log/query helpers.
• apps/web/src/lib/webhooks/: producer, deliver (HMAC), consumer (backoff + DLQ), scheduled (sweep + cleanup).
• tRPC: form.update webhook fields + server-generated secret, form.testWebhook, form.listDeliveries; setFormData now returns { id }; queue threaded through context.
• config: wrangler.jsonc queues/DLQ/cron + main → ./worker.ts; cloudflare-env.d.ts gitignored; tsconfig checkJs:false.
• Deleted the stale apps/worker/ and packages/queue/ leftovers from feat: add webhook queue system and worker #121.

Verification

• @formbase/db, @formbase/utils, @formbase/api: typecheck clean.
• apps/web: no typecheck/lint errors in any webhook file.
• Reviewed by an adversarial multi-lens pass (workerd runtime, queue/retry/idempotency, HMAC, type boundaries, migration, SSRF).

Before deploying

1. Create the queues: wrangler queues create formbase-webhooks and wrangler queues create formbase-webhooks-dlq.
2. Apply the migration (packages/db → db:migrate).
3. Queue/cron handlers only run under wrangler dev / opennextjs-cloudflare preview (not next dev); validate end-to-end against a webhook.site URL.

Known follow-ups (low severity)

• DLQ markFailed could be wrapped in try/finally before ack().
• isValidWebhookUrl denylist has IPv6/numeric-host gaps (backstopped by global_fetch_strictly_public).
• Test button reads the saved URL prop rather than the live field value.

[cloudflare-workers-and-pages]

Deploying with    Cloudflare Workers

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	formbase-web	5222cad	Commit Preview URL Branch Preview URL	Jun 06 2026, 08:30 PM

[aikins01]

sweet

[aikins01]

thanks for pushing this forward. i found a few blockers that need fixing before this can merge: CI is failing, the public form lookup exposes webhook targets, and the stuck-delivery sweep can overrun queue batch limits.