Use with NestJS

[rbgfloripa]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the issue has not already been raised

Issue

Hi all,

Does anyone already use it in production with NestJS?
Is it possible to send me an example?

I searched and didn't find any information about this.
The only article I found (on Medium) uses old versions.

TIA,

Rafael.

[adrai]

maybe @cefamax can help?

btw: if an old version of aws-lambda-fastify worked, the newest version should still work

[rbgfloripa]

Hi,

Yes, old version works, but with old versions of nest.
The example code no longer works.
So I wanted some help to test it with current versions (nest 8+).

Thanks

Rafael.

[adrai]

Hi,

Yes, old version works, but with old versions of nest. The example code no longer works. So I wanted some help to test it with current versions (nest 8+).

Thanks

Rafael.

Sorry, I'm not a nest user, you may try to ask at the nest community or stackoverflow.

[rbgfloripa]

Yeah... I already tried :-(
I didn't find it anywhere
But thanks man.
I will keep trying to make it work.

[cefamax]

hi @rbgfloripa, I write you the lambda.ts file contents. I use in production "aws-lambda-fastify": "^2.2.0" nodejs 16.x.
I hope it helps you.
`
import { NestFactory } from '@nestjs/core';
import { FastifyAdapter, NestFastifyApplication } from '@nestjs/platform-fastify';
import { FastifyServerOptions, FastifyInstance, fastify } from 'fastify';
import awsLambdaFastify from 'aws-lambda-fastify';
import { AppModule } from './app.module';
import {
Context,
APIGatewayProxyEvent,
APIGatewayProxyResult
} from 'aws-lambda';
import { Logger, LogLevel } from '@nestjs/common';

interface NestApp {
app: NestFastifyApplication;
instance: FastifyInstance;
}

let cachedNestApp: NestApp;
let cachedProxy;

async function bootstrapServer(): Promise {

const serverOptions: FastifyServerOptions = {
    logger: (process.env.LOGGER || '0') == '1',
};
const instance: FastifyInstance = fastify(serverOptions);
const app = await NestFactory.create<NestFastifyApplication>(
    AppModule,
    new FastifyAdapter(instance),
    {
        logger: !process.env.AWS_EXECUTION_ENV ? new Logger() : console,
    },
);

const CORS_OPTIONS = {
    origin: '*',
    allowedHeaders: '*',
    exposedHeaders: '*',
    credentials: false,
    methods: ['GET', 'PUT', 'OPTIONS', 'POST', 'DELETE'],
};

app.register(require('fastify-cors'), CORS_OPTIONS);

app.setGlobalPrefix(process.env.API_PREFIX);

await app.init();

return {
    app,
    instance
};

}

export const handler = async (event: APIGatewayProxyEvent, context: Context): Promise => {

if (!cachedProxy) {

    if (!cachedNestApp) {
        cachedNestApp = await bootstrapServer();
    }
    cachedProxy = awsLambdaFastify(cachedNestApp.instance, { decorateRequest: true });
}

return cachedProxy(event, context);

};
`

[rbgfloripa]

Thanks a lot man.
I'll test it right now.

[dustingraves]

Anyone using v3 with nestjs?

[Jwagner347]

@cefamax I was able to get my fastify/mercurius graphql app running locally through serverless-offline thanks to your suggestion above; however, when I deployed to AWS, I am getting an error: EROFS: read-only file system, mkdir '/var/task/src'.

I don't know where Nest is trying to write to the lambda file system but happens right after INFO Mapped {/, GET} route RouterExplorer in the logs. Any idea where this might be happening and how to fix?

[cefamax]

@Jwagner347 I have no idea what it could be, with the information you wrote. Nest shouldn't write anything to that folder. You could try building a clean nestjs application to see if it works in aws and then add the other components to check if anything outside of nest can give that problem.

[Uzlopak]

aws-samples/aws-lambda-elixir-runtime#7
https://stackoverflow.com/questions/53810516/getting-error-aws-lambda-erofs-read-only-file-system-open-var-task-assets
https://stackoverflow.com/questions/49020710/lambda-enoent-no-such-file-or-directory

/var/task is where your Lambda function code is located, and in the actual Lambda environment, that filesystem is read-only. If you need to write to a file, you need to write to /tmp.

Q: What if I need scratch space on disk for my AWS Lambda function?

Each Lambda function receives 500MB of non-persistent disk space in its own /tmp directory.

https://aws.amazon.com/lambda/faqs/

[Jwagner347]

@Uzlopak I know you can only write to /tmp in lambda, my issue is that I don't know why NestJS application is trying to write in the first place. It looks like when I call app.init() I get that error.

[Jwagner347]

@cefamax I was able to figure it out. It's a GraphQL application, and I was using autoSchemaFile, which was trying to write the schema file on initialization. I just had to change it to only run locally and then copy over the schema during my build before deploying to lambda.

Thanks for your help, the code you initially posted helped me a lot to get up and running with fastify/mercurius in lambda. One thing I don't understand though is you are caching the proxy in addition to the app. Everywhere else I see proxy is just called directly. What is the reason for this?

[Uzlopak]

@Jwagner347

Can you improve the readme.md to persist that knowledge?

[cefamax]

@Jwagner347 I had read a comment by @mcollina where he recommends doing it, but now I can't find it to send it to you. However I have been using this system for several months, I have never had any problems.

[climba03003]

What is the reason for this?

In most of the server-less environment, handler will be called everytime for a request and anything outside may cached between calls (determined by how long the environment may spin down).

By using a variables cache, it will minimize the cold-start time of fastify since it will be construct once vs construct everytime.