Setting up a GraphQL server in Javascript on AWS Lambda

Setting up a GraphQL server in JavaScript on AWS Lambda can be a powerful way to build scalable and flexible APIs for your web and mobile applications. In this blog post, we will walk through the steps of setting up a GraphQL server using Node.js and the express-graphql library, and deploying it to AWS Lambda.

Prerequisites

Before we get started, you will need to have the following tools installed:

• Node.js and npm (or yarn)

• Terraform

Setting up your project

First, create a new directory for your project and initialize a new Node.js project using npm or yarn. The folder structure is like this

src
- graql-server
  index.ts
babel.config.js
package.json
tsconfig.json

yarn add @apollo/server graphql @as-integrations/aws-lambda

src/graphql-post/index.ts

require('dotenv').config()

import { ApolloServer } from '@apollo/server'
import {
  ApolloServerPluginLandingPageLocalDefault,
  ApolloServerPluginLandingPageProductionDefault,
} from '@apollo/server/plugin/landingPage/default'
import {
  startServerAndCreateLambdaHandler,
  handlers,
} from '@as-integrations/aws-lambda'

import resolvers from './resolvers'

const typeDefs = require('./schema.graphql')
const server = new ApolloServer({
  typeDefs,
  resolvers,
  introspection: true,
  csrfPrevention: true,
  cache: 'bounded',
  plugins: [
    process.env.NODE_ENV === 'production'
      ? ApolloServerPluginLandingPageProductionDefault()
      : ApolloServerPluginLandingPageLocalDefault({ embed: true }),
  ],
})

console.info('Starting graphql server')

export const handler = startServerAndCreateLambdaHandler(
  server,
  handlers.createAPIGatewayProxyEventRequestHandler(),
  {
    middleware: [
      // to support CORS for Apollo Studio
      async event => {
        return async result => {
          result.headers = {
            ...result.headers,
            'access-control-allow-headers': 'Content-Type',
            'access-control-allow-origin': '*',
            'access-control-allow-methods': 'GET, POST, OPTIONS',
          }
        }
      },
    ],
  }
)

Provision AWS lambda function

Please refer to the lambda provision page.

Send hello query on GraphQL Playground

Make sure you have Homebrew installed on your machine and install GraphQL Playground using Homebrew.

brew install --cask graphql-playground

Open up Spotlight Search by pressing cmd + space and rRun GraphQL Playground by typing graphql-playground. This will start a local instance of GraphQL Playground

In the GraphQL Playground, enter the following query in the left panel:

query {
  hello
}

Click the “Play” button to send the query. You should see a response like:

{
  "data": {
    "hello": "Hello world!"
  }
}

Testing

import { handler as graphqlJobs } from '../../src/graphql/index'
import getJobGraphQlEvent from '../../events/graphql-event-job'
import {
  APIGatewayProxyEvent,
  APIGatewayProxyResult,
  Context,
} from 'aws-lambda'
import { ddbDocClient } from '../../src/common/dynamodbClient'

describe('job tests', () => {
  const context: Context = {
    callbackWaitsForEmptyEventLoop: false,
    functionName: 'string',
    functionVersion: 'string',
    invokedFunctionArn: 'string',
    memoryLimitInMB: 'string',
    awsRequestId: 'string',
    logGroupName: 'string',
    logStreamName: 'string',
    getRemainingTimeInMillis() {
      return 1
    },
    done() {},
    fail() {},
    succeed() {},
  }

  const job = {
    jobNo: 'jobNo',
    jobStatus: 'COMPLETED',
    jobNotes:
      'replaced bent clip and hose.  hose would not fit into manifold so had to replace it.',
    reportDateTime: null,
    creationDateTime: '2023-01-10T15:20:32.275Z',
  }

  ddbDocClient.send = jest.fn().mockResolvedValue({ Item: job })

  it('should return the list of jobs given companyId', async () => {
    const result = (await graphqlJobs(
      getJobGraphQlEvent as APIGatewayProxyEvent,
      context,
      () => {}
    )) as APIGatewayProxyResult

    expect(JSON.parse(result.body)).toEqual({
      data: { job },
    })
  })
})