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Deploying with AWS Lambda

How to deploy Apollo Server with AWS Lambda

AWS Lambda is a service that allows users to run code without provisioning or managing servers. Cost is based on the compute time that is consumed, and there is no charge when code is not running.

This guide explains how to setup Apollo Server 2 to run on AWS Lambda using Serverless Framework. To use CDK and SST instead, follow this tutorial.

Prerequisites

The following must be done before following this guide:

Setting up your project

Setting up a project to work with Lambda isn't that different from a typical NodeJS project.

First, install the apollo-server-lambda package:

npm install apollo-server-lambda@3.x graphql

Next, set up the schema's type definitions and resolvers, and pass them to the ApolloServer constructor like normal. Here, ApolloServer must be imported from apollo-server-lambda. It's also important to note that this file must be named graphql.js, as the config example in a later step depends on the filename.

// graphql.js

const { ApolloServer, gql } = require('apollo-server-lambda');

// Construct a schema, using GraphQL schema language
const typeDefs = gql`
  type Query {
    hello: String
  }
`;

// Provide resolver functions for your schema fields
const resolvers = {
  Query: {
    hello: () => 'Hello world!',
  },
};

const server = new ApolloServer({ typeDefs, resolvers });

exports.graphqlHandler = server.createHandler();

Finally, pay close attention to the last line. This creates an export named graphqlHandler with a Lambda function handler.

Deploying with the Serverless Framework

Serverless is a framework that makes deploying to services like AWS Lambda simpler.

Configuring the Serverless Framework

Serverless uses a config file named serverless.yml to determine what service to deploy to and where the handlers are.

For the sake of this example, the following file can just be copied and pasted into the root of your project.

# serverless.yml

service: apollo-lambda
provider:
  name: aws
  runtime: nodejs14.x
functions:
  graphql:
    # this is formatted as <FILENAME>.<HANDLER>
    handler: graphql.graphqlHandler
    events:
    - http:
        path: graphql
        method: post
        cors: true
    - http:
        path: graphql
        method: get
        cors: true

Running the Serverless Framework

After configuring the Serverless Framework, all you have to do to deploy is run serverless deploy

If successful, serverless should output something similar to this example:

> serverless deploy
Serverless: Packaging service...
Serverless: Excluding development dependencies...
Serverless: Uploading CloudFormation file to S3...
Serverless: Uploading artifacts...
Serverless: Uploading service .zip file to S3 (27.07 MB)...
Serverless: Validating template...
Serverless: Updating Stack...
Serverless: Checking Stack update progress...
..............
Serverless: Stack update finished...
Service Information
service: apollo-lambda
stage: dev
region: us-east-1
stack: apollo-lambda-dev
api keys:
  None
endpoints:
  POST - https://ujt89xxyn3.execute-api.us-east-1.amazonaws.com/dev/graphql
  GET - https://ujt89xxyn3.execute-api.us-east-1.amazonaws.com/dev/graphql
functions:
  graphql: apollo-lambda-dev-graphql

What does serverless do?

First, it builds the functions, zips up the artifacts, and uploads the artifacts to a new S3 bucket. Then, it creates a Lambda function with those artifacts, and if successful, outputs the HTTP endpoint URLs to the console.

Managing the resulting services

The resulting S3 buckets and Lambda functions can be viewed and managed after logging in to the AWS Console.

  • To find the created S3 bucket, search the listed services for S3. For this example, the bucket created by Serverless was named apollo-lambda-dev-serverlessdeploymentbucket-1s10e00wvoe5f
  • To find the created Lambda function, search the listed services for Lambda. If the list of Lambda functions is empty, or missing the newly created function, double check the region at the top right of the screen. The default region for Serverless deployments is us-east-1 (N. Virginia)

Customizing HTTP serving

apollo-server-lambda is built on top of apollo-server-express. It combines the HTTP server framework express with a package called @vendia/serverless-express that translates between Lambda events and Express requests. By default, this is entirely behind the scenes, but you can also provide your own express app with the expressAppFromMiddleware option to createHandler:

const { ApolloServer } = require('apollo-server-lambda');
const express = require('express');

exports.handler = server.createHandler({
  expressAppFromMiddleware(middleware) {
    const app = express();
    app.use(someOtherMiddleware);
    app.use(middleware);
    return app;
  }
});

Getting request info

Your ApolloServer's context function can read information about the current operation from both the original Lambda data structures and the Express request and response created by @vendia/serverless-express. These are provided to your context function as event, context, and express options.

The event object contains the API Gateway event (HTTP headers, HTTP method, body, path, ...). The context object (not to be confused with the context function itself!) contains the current Lambda Context (Function Name, Function Version, awsRequestId, time remaining, ...). express contains req and res fields with the Express request and response. The object returned from your context function is provided to all of your schema resolvers in the third context argument.

const { ApolloServer, gql } = require('apollo-server-lambda');

// Construct a schema, using GraphQL schema language
const typeDefs = gql`
  type Query {
    hello: String
  }
`;

// Provide resolver functions for your schema fields
const resolvers = {
  Query: {
    hello: () => 'Hello world!',
  },
};

const server = new ApolloServer({
  typeDefs,
  resolvers,
  context: ({ event, context, express }) => ({
    headers: event.headers,
    functionName: context.functionName,
    event,
    context,
    expressRequest: express.req,
  }),
});

exports.graphqlHandler = server.createHandler();
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