aws-rpc

This is the easiest way to expose any plain old JS object as AWS Lambda.

How to use it

Suppose you have an object that you want to expose. Here is an example interface of it:

export interface TestService {
    test(): Promise<string>;
}

Here is its implementation:

import { TestService } from './TestService';

export class TestServiceImpl implements TestService {
    private readonly field: string = "42";
    test(): Promise<string> {
        return Promise.resolve(this.field);
    }
}

First, you will need to make a handler for your AWS Lambda:

import { lambdaHandler } from 'aws-rpc';
import { TestServiceImpl } from './TestServiceImpl';

export const handler = lambdaHandler(new TestServiceImpl());

Now, you can just deploy "handler" as AWS Lambda. Here is how you invoke its methods:

import { TestService } from './TestService';

const client = await createClient<TestService>("LambdaName", "test");
console.log(await client.test()); // 42

How can I test it locally?

You can expose the object as a http service:

import { runService } from 'aws-rpc';
import { TestServiceImpl } from './TestServiceImpl';

export const handler = runService(new TestServiceImpl(), 9090);

Then, you can create a client for it:

import { TestService } from './TestService';

const client = await createClient<TestService>(9090, "test");
console.log(await client.test()); // 42

Important

In order to be able to generate stub methods for the object, you have to pass all the method names to createClient, like we did in the example.

This is required, because JS does not have any runtime information about TypeScript interfaces.