ferdy•2y ago

trpc + AWS Lambda (through cdk)

Hi all, has anyone successfully integrated tRPC with AWS Lambda? My current stack is API Gateway + Lambda, all created through cdk. I am trying to figure out how to hook up the tRPC router and client to the lambda code. This is my first time using tRPC 😅

36 Replies

Nick•2y ago

Have you looked at the Lambda Adapter and its docs?

ferdyOP•2y ago

yeah, I have been trying to figure out how to make that sample code work. But it doesn't show me how to fit that code into the surrounding cdk infrastructure. I see that they export a handler:

export const handler = awsLambdaRequestHandler(...)

export const handler = awsLambdaRequestHandler(...)

but when I try to reference that handler from cdk it's not quite working:

const testLambda = new aws_lambda.Function(this, "testLambda", {
      handler:("/path/to/ApiEntryPoint.handler"),
...

const testLambda = new aws_lambda.Function(this, "testLambda", {
      handler:("/path/to/ApiEntryPoint.handler"),
...

Lois•2y ago

remember to add AWS extension in your VSCode the prompt + autocomplete is good

Nick•2y ago

So exporting a handler is a standard lambda thing, that’s the boundary of your application At that point you’re looking at CDK docs to integrate, though honestly I haven’t used CDK. For my own local dev I just use a standalone trpc adapter, and the lambda adapter is just for AWS deployments

ferdyOP•2y ago

ok I got it mostly figured out -- for any other wayward souls with this issue, check out this github repo that really helped me out: https://github.com/jacksonludwig/trpc-repro

GitHub

GitHub - jacksonludwig/trpc-repro

Contribute to jacksonludwig/trpc-repro development by creating an account on GitHub.

ferdyOP•2y ago

@Nick Lucas thanks for the help. I have one more question: when creating my client typescript keeps complaining to me that I am not providing a transformer, and I don't really know what I am supposed to pass in for that. The sample code I linked above doesn't seem to have to do that, I guess because they are not using createTRPCProxyClient. Do you know why that is or what I can use as a transformer?

Nick•2y ago

That's a tRPC thing, check the docs for transformers 🙂 It's easy!

ferdyOP•2y ago

I will, though I am still curious why every example I've seen of the proxy client doesnt include having to specify a transformer

Nick•2y ago

You don't have to, but you also can't go half in, which is what you might have inadvertently done if it's moaning at you

ferdyOP•2y ago

const client = createTRPCProxyClient<AppRouter>({
    links: [
      httpBatchLink({
        url: "https://xxxxxxxx.execute-api.us-west-2.amazonaws.com/prod/"
      })
    ],
  });

const client = createTRPCProxyClient<AppRouter>({
    links: [
      httpBatchLink({
        url: "https://xxxxxxxx.execute-api.us-west-2.amazonaws.com/prod/"
      })
    ],
  });

^^^ this doesnt compile

Nick•2y ago

Can you share your appRouter too?

ferdyOP•2y ago

yeah

export const createContext = (_: CreateAWSLambdaContextOptions<APIGatewayProxyEventV2>) => ({});
type Context = inferAsyncReturnType<typeof createContext>;

const t = initTRPC.context<Context>().create();

export const middleware = t.middleware;
export const router = t.router;
export const procedure = t.procedure;
export const mergeRouters = t.mergeRouters;

const appRouter = router({
  testRoute: procedure.query(async () => {
    // mock fast db lookup
    await new Promise((res) => setTimeout(res, 100));

    return {
      value: 5,
    };
  }),
  testRoute2: procedure.query(async () => {
    await new Promise((res) => setTimeout(res, 100));

    return {
      obj: {
        value: 10,
      },
    };
  }),
});

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

export type AppRouter = typeof appRouter;

export const createContext = (_: CreateAWSLambdaContextOptions<APIGatewayProxyEventV2>) => ({});
type Context = inferAsyncReturnType<typeof createContext>;

const t = initTRPC.context<Context>().create();

export const middleware = t.middleware;
export const router = t.router;
export const procedure = t.procedure;
export const mergeRouters = t.mergeRouters;

const appRouter = router({
  testRoute: procedure.query(async () => {
    // mock fast db lookup
    await new Promise((res) => setTimeout(res, 100));

    return {
      value: 5,
    };
  }),
  testRoute2: procedure.query(async () => {
    await new Promise((res) => setTimeout(res, 100));

    return {
      obj: {
        value: 10,
      },
    };
  }),
});

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

export type AppRouter = typeof appRouter;

Nick•2y ago

What's the compile error for your example? This does look fine so it's weird you're having an issue

ferdyOP•2y ago

TS2345: Argument of type '{ links: TRPCLink<CreateRouterInner<RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>, { testRoute: BuildProcedure<"query", { _config: RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>; ... 5 more ...; _meta: object; }, { ...; ...' is not assignable to parameter of type 'CreateTRPCClientOptions<CreateRouterInner<RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>, { testRoute: BuildProcedure<"query", { _config: RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>; ... 5 more ...; _meta: object; }, {...'.   Property 'transformer' is missing in type '{ links: TRPCLink<CreateRouterInner<RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>, { testRoute: BuildProcedure<"query", { _config: RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>; ... 5 more ...; _meta: object; }, { ...; ...' but required in type '{ transformer: DataTransformerOptions; }'.

TS2345: Argument of type '{ links: TRPCLink<CreateRouterInner<RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>, { testRoute: BuildProcedure<"query", { _config: RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>; ... 5 more ...; _meta: object; }, { ...; ...' is not assignable to parameter of type 'CreateTRPCClientOptions<CreateRouterInner<RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>, { testRoute: BuildProcedure<"query", { _config: RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>; ... 5 more ...; _meta: object; }, {...'.   Property 'transformer' is missing in type '{ links: TRPCLink<CreateRouterInner<RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>, { testRoute: BuildProcedure<"query", { _config: RootConfig<{ ctx: {}; meta: object; errorShape: never; transformer: DataTransformerOptions; }>; ... 5 more ...; _meta: object; }, { ...; ...' but required in type '{ transformer: DataTransformerOptions; }'.

Nick•2y ago

Hm, what's your @trpc/* version? Are they all identical?

ferdyOP•2y ago

"@trpc/server": "^10.14.0",
"@trpc/client": "^10.14.0",

"@trpc/server": "^10.14.0",
"@trpc/client": "^10.14.0",

Nick•2y ago

I've definitely seen someone else asking about this, and I think they resolved it, just can't find it now

ferdyOP•2y ago

ok ill search around as well

Nick•2y ago

Reload your editor / TS language server and restart your build if you haven't

ferdyOP•2y ago

no luck with that

Nick•2y ago

bah, this is a weird one This is an error that appears when you have set a transformer on the API but not on the frontend It's intentional and I can reproduce that in my own codebase But transformers are optional I suspect it might be something weird related to your repo setup. If you install superjson and get that set up, do any new errors appear?

ferdyOP•2y ago

I was able to pass in superjson and get around the error, but then the response from my lambda was coming back undefined -- I was wondering if the default transformer would've just handled the response correctly

Nick•2y ago

At runtime?

ferdyOP•2y ago

yep. and I tested out calling the api directly in my aws console, confirmed its working. Also confirmed that the lambda is getting invoked when I call it from the client by double checking logs it's just the return value isn't getting processed correctly

Nick•2y ago

That might be something more related to API Gateway if you're using that honestly AWS is a weird balancing act in my experience There's talk to adding some more in-depth docs but we're not there yet

ferdyOP•2y ago

it definitely could be an apig oddity, though I can see it in the console returning the json response correctly. Maybe I need to find somewhere in between that I can inspect to see where that response is getting lost... Like a debug log from the trpc client or something

Nick•2y ago

Yep I put console logs at several stages, exported my own handler and called the lambda adapter's handler within it so I could log before and after. It's a pain but that's AWS 😄 Did also have some similar teething troubles like you

ferdyOP•2y ago

ok I got it working -- truly dont understand this yet but adding Context to the type parameter of create did the trick:

export const createContext = ({event, context}: CreateAWSLambdaContextOptions<APIGatewayProxyEventV2>) => ({});
type Context = inferAsyncReturnType<typeof createContext>;

const t = initTRPC.context<Context>().create<Context>();

export const createContext = ({event, context}: CreateAWSLambdaContextOptions<APIGatewayProxyEventV2>) => ({});
type Context = inferAsyncReturnType<typeof createContext>;

const t = initTRPC.context<Context>().create<Context>();

also fixed having to supply a transformer

Nick•2y ago

Huh, that’s very weird Typescript issue maybe? Is strict mode enabled?

ferdyOP•2y ago

ohh no it wasnt. I didn't do the initial setup of this codebase, didn't even notice strict wasnt on. Enabling strict mode and removing the extra <Context> works, compile-wise -- not sure yet about runtime

Nick•2y ago

That’s good, strict mode fixes a lot of stuff in these well-typed frameworks

Unknown User•2y ago

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Falo•2y ago

Ferdy, i'm wondering how to push the code on aws, did you compile your code with tsc and send the dist folder to aws lambda ? Because i have a tons of problem with tsc and running the js file

ferdyOP•2y ago

i do everything through cdk, specifically using NodejsFunction

ferdyOP•2y ago

https://docs.aws.amazon.com/cdk/api/v1/docs/@aws-cdk_aws-lambda-nodejs.NodejsFunction.html

class NodejsFunction (construct) · AWS CDK

class NodejsFunction (construct)

ferdyOP•2y ago

some better examples: https://snyk.io/advisor/npm-package/@aws-cdk/aws-lambda-nodejs/functions/@aws-cdk%2Faws-lambda-nodejs.NodejsFunction

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trpc + AWS Lambda (through cdk)

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