Bundling Prisma with the CDK using aws-lambda-nodejs

#prisma #aws #lambda #typescript

Introduction

In this post, we shall see how we can bundle Prisma using aws-lambda-nodejs with the CDK.

Prerequisites

This is a walkthrough of the steps required to bundle Prisma with CDK and so cloning the repo below and following along would be ideal.

ryands17 / prisma-lambda

Integrating Prisma with `aws-lambda-nodejs` to run Prisma on Lambda

Constructs

In this project, we have a simple Lambda function that uses Prisma to query data from a User table and logs to the console. The only resource we create here is the Lambda function so let's look at that.

I'm skipping the imports in these snippets to make it smaller but if you want to view those you can check those out in the file mentioned in the comments.

// lib/prisma-lambda-stack.ts

new ln.NodejsFunction(this, 'prisma', {
  runtime: lambda.Runtime.NODEJS_14_X,
  handler: 'handler',
  entry: lambdaFn,
  timeout: cdk.Duration.seconds(10),
  environment: {
    DB_URL: process.env.DB_URL || '',
  },
  bundling: {
    nodeModules: ['@prisma/client', 'prisma'],
    commandHooks: {
      beforeBundling(inputDir: string, outputDir: string): string[] {
        return []
      },
      beforeInstall(inputDir: string, outputDir: string) {
        return [`cp -R ../prisma ${outputDir}/`]
      },
      afterBundling(inputDir: string, outputDir: string): string[] {
        return [
          `cd ${outputDir}`,
          `yarn prisma generate`,
          `rm -rf node_modules/@prisma/engines`,
        ]
      },
    },
  },
})

Here, we create a simple Node.js Lambda function and the parameters like runtime, handler, entry, timeout and environment are the basic Lambda parameters that we pass.

aws-lambda-nodejs uses esbuild under the hood so your function is bundled using esbuild. There are a couple of important parameters that we need to set for the bundling process.

The first is nodeModules. This will instruct esbuild to not include @prisma/client and prisma into our function file and treat them as node_modules.
The other section to be configured is commandHooks. The main hooks we need here are beforeInstall and afterBundling.
- In beforeInstall, we run the command cp -R ../prisma ${outputDir}/. This makes sure we have schema.prisma present in the bundle. You can also directly copy schema.prisma instead of the entire directory if you have the migrations folder which is not required in the bundle.
- The other hook we use is afterBundling. This is to generate PrismaClient and to remove the engines folder to reduce function size.