AWS Lambda durable functions now live

Lambda durable functions are here, and they're a big deal for anyone building complex workflows.

Here's what just shipped: You can now write sequential multi-step applications directly in Lambda. Think approval workflows, payment processing chains, AI agent orchestration. No more wrestling with state machines or SQS choreography.

The core idea? Checkpoint and replay. Your function executes, hits a checkpoint, and if something breaks, Lambda resumes from that exact point. Completed steps get skipped. Failures inside steps? Automatic retries kick in based on your strategy.

The primitives are simple:

Steps — Add automatic checkpointing and retry logic to your business logic. Once done, skipped on replay.

Wait — Pause execution for a duration. Function terminates, no compute charges while suspended.

Callbacks — Await external events. Human approvals. API responses. Whatever. Execution hangs there, zero cost.

The order processing example in the announcement is instructive. Validate order. Send for approval (callback). Wait. Process order with custom retry logic. If validation fails outside a step, that's a terminal error—stops immediately. If something fails inside a step, retry logic takes over.

Built-in idempotency too. Invoke twice with the same execution name, second call returns the existing result. No duplicates.

You can monitor everything in the Lambda console or wire up EventBridge for downstream workflows. The SDKs are open source. JavaScript/TypeScript and Python at launch. US East (Ohio) region to start.

This removes a ton of friction. No more custom state management. No more orchestration overhead. Just write the workflow, let Lambda handle the rest.