AWS Lambda + API Gateway Adapter - Trpc

AWS Lambda adapter

The AWS Lambda adapter is supported for API Gateway REST API(v1) and HTTP API(v2), and Lambda Function URL use cases.

httpBatchLink requires the router to work on a single API Gateway Resource (as shown in the example). If you'd like to have a Resource per procedure, you can use the httpLink instead (more info).

Example apps

<table> <thead> <tr> <th>Description</th> <th>Links</th> </tr> </thead> <tbody> <tr> <td>API Gateway with NodeJS client.</td> <td> <ul> <li><a href="https://github.com/trpc/trpc/tree/main/examples/lambda-api-gateway">Source</a></li> </ul> </td> </tr> <tr> <td>API Gateway REST API with response streaming.</td> <td> <ul> <li><a href="https://github.com/trpc/trpc/tree/main/examples/lambda-api-gateway-streaming">Source</a></li> </ul> </td> </tr> </tbody> </table>

How to add tRPC

1. Install deps

bash

yarn add @trpc/server

:::tip AI Agents If you use an AI coding agent, install tRPC skills for better code generation:

bash

npx @tanstack/intent@latest install

:::

2. Create a tRPC router

Implement your tRPC router. A sample router is given below:

import { initTRPC } from '@trpc/server';
import { z } from 'zod';

export const t = initTRPC.create();

const appRouter = t.router({
  getUser: t.procedure.input(z.string()).query((opts) => {
    opts.input; // string
    return { id: opts.input, name: 'Bilbo' };
  }),
});

// export type definition of API
export type AppRouter = typeof appRouter;

3. Use the Amazon API Gateway adapter

tRPC includes an adapter for API Gateway out of the box. This adapter lets you run your routes through the API Gateway handler.

// @filename: router.ts
import { initTRPC } from '@trpc/server';
const t = initTRPC.create();
export const appRouter = t.router({});
export type AppRouter = typeof appRouter;

// @filename: server.ts
// ---cut---
import type { APIGatewayProxyEventV2 } from 'aws-lambda';
import type { CreateAWSLambdaContextOptions } from '@trpc/server/adapters/aws-lambda';
import { awsLambdaRequestHandler } from '@trpc/server/adapters/aws-lambda';
import { appRouter } from './router';

// created for each request
const createContext = ({
  event,
  context,
}: CreateAWSLambdaContextOptions<APIGatewayProxyEventV2>) => ({}); // no context
type Context = Awaited<ReturnType<typeof createContext>>;

export const handler = awsLambdaRequestHandler({
  router: appRouter,
  createContext,
})

Build & deploy your code, now use your API Gateway URL to call your function.

Endpoint	HTTP URI
`getUser`	`GET https://<execution-api-link>/getUser?input=INPUT`

where INPUT is a URI-encoded JSON string. |

A word about payload format version

API Gateway has two different event data formats when it invokes a Lambda. For REST APIs they should be version "1.0"(APIGatewayProxyEvent), but you can choose which for HTTP APIs by stating either version "1.0" or "2.0".

Version 1.0: APIGatewayProxyEvent
Version 2.0: APIGatewayProxyEventV2

To infer what version you might have, supply the context as following:

import type { APIGatewayProxyEvent } from 'aws-lambda';
import type { CreateAWSLambdaContextOptions } from '@trpc/server/adapters/aws-lambda';

// ---cut---
function createContext({
  event,
  context,
}: CreateAWSLambdaContextOptions<APIGatewayProxyEvent>) {
  // ...
}

// CreateAWSLambdaContextOptions<APIGatewayProxyEvent> or CreateAWSLambdaContextOptions<APIGatewayProxyEventV2>

AWS Lambda Response Streaming Adapter

AWS Lambda supports streaming responses to clients with both Lambda Function URLs and API Gateway REST APIs.

Response streaming is supported for Lambda Function URLs and API Gateway REST APIs. For API Gateway REST APIs, you need to configure the integration with responseTransferMode: STREAM. Read more about Lambda response streaming and API Gateway response streaming.

Response Streaming

The signature of a streaming handler is different from the default handler. The streaming handler additionally receives a writable stream parameter, responseStream, besides the default node handler parameters, event and context. To indicate that Lambda should stream your responses, you must wrap your function handler with the awslambda.streamifyResponse() decorator.

Note that the awslambda namespace is automatically provided by the Lambda execution environment. You can import the types from @types/aws-lambda to augment the global namespace with the awslambda namespace.

/// <reference types="aws-lambda" />
// @filename: router.ts
import { initTRPC } from '@trpc/server';
const t = initTRPC.create();
export const appRouter = t.router({
  iterable: t.procedure.query(async function* () {
    for (let i = 0; i < 10; i++) {
      await new Promise((resolve) => setTimeout(resolve, 500));
      yield i;
    }
  }),
});

// @filename: server.ts
// ---cut---
/// <reference types="aws-lambda" />
import type { APIGatewayProxyEventV2 } from 'aws-lambda';
import type { CreateAWSLambdaContextOptions } from '@trpc/server/adapters/aws-lambda';
import { awsLambdaStreamingRequestHandler } from '@trpc/server/adapters/aws-lambda';
import { appRouter } from './router';

// created for each request
const createContext = ({
  event,
  context,
}: CreateAWSLambdaContextOptions<APIGatewayProxyEventV2>) => ({
  // your context
});
type Context = Awaited<ReturnType<typeof createContext>>;

export const handler = awslambda.streamifyResponse(
  awsLambdaStreamingRequestHandler({
    router: appRouter,
    createContext,
  }),
);