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NextjsSite

The NextjsSite construct is a higher level CDK construct that makes it easy to create a Next.js app. It provides a simple way to build and deploy the site to an S3 bucket; setup a CloudFront CDN for fast content delivery; and configure a custom domain for the website URL.

It also allows you to automatically set the environment variables in your Next.js app directly from the outputs in your SST app.

Next.js Features

The NextjsSite construct uses the @sls-next/lambda-at-edge package from the serverless-next.js project to build and package your Next.js app so that it can be deployed to Lambda@Edge and CloudFront.

note

To use the NextjsSite construct, you have to install @sls-next/lambda-at-edge as a dependency in your package.json.

npm install --save @sls-next/lambda-at-edge

Most of the Next.js 11 features are supported, including:

Next.js 12 features like middleware and AVIF image are not yet supported. You can read more about the features supported by serverless-next.js. And you can follow the progress on Next.js 12 support here.

Examples

Creating a Next.js app

Deploys a Next.js app in the path/to/site directory.

new NextjsSite(stack, "NextSite", {
path: "path/to/site",
});

Environment variables

The NextjsSite construct allows you to set the environment variables in your Next.js app based on outputs from other constructs in your SST app. So you don't have to hard code the config from your backend. Let's look at how.

Next.js supports setting build time environment variables. In your JS files this looks like:

pages/index.js
console.log(process.env.API_URL);
console.log(process.env.USER_POOL_CLIENT);

You can pass these in directly from the construct.

new NextjsSite(stack, "NextSite", {
path: "path/to/site",
environment: {
API_URL: api.url,
USER_POOL_CLIENT: auth.cognitoUserPoolClient.userPoolClientId,
},
});

Where api.url or auth.cognitoUserPoolClient.userPoolClientId are coming from other constructs in your SST app.

While deploying

On sst deploy, the environment variables will first be replaced by placeholder values, {{ API_URL }} and {{ USER_POOL_CLIENT }}, when building the Next.js app. And after the referenced resources have been created, the Api and User Pool in this case, the placeholders in the HTML and JS files will then be replaced with the actual values.

caution

Since the actual values are determined at deploy time, you should not rely on the values at build time. For example, you cannot fetch from process.env.API_URL inside getStaticProps() at build time.

There are a couple of work arounds:

  • Hardcode the API URL
  • Read the API URL dynamically at build time (ie. from an SSM value)
  • Use fallback pages to generate the page on the fly

While developing

To use these values while developing, run sst start to start the Live Lambda Development environment.

npx sst start

Then in your Next.js app to reference these variables, add the sst-env package.

npm install --save-dev @serverless-stack/static-site-env

And tweak the Next.js dev script to:

package.json
"scripts": {
"dev": "sst-env -- next dev",
"build": "next build",
"start": "next start"
},

Now you can start your Next.js app as usual and it'll have the environment variables from your SST app.

npm run dev

There are a couple of things happening behind the scenes here:

  1. The sst start command generates a file with the values specified by the NextjsSite construct's environment prop.
  2. The sst-env CLI will traverse up the directories to look for the root of your SST app.
  3. It'll then find the file that's generated in step 1.
  4. It'll load these as environment variables before running the start command.
note

sst-env only works if the Next.js app is located inside the SST app or inside one of its subdirectories. For example:

/
sst.json
nextjs-app/

Custom domains

You can configure the website with a custom domain hosted either on Route 53 or externally.

Using the basic config (Route 53 domains)

new NextjsSite(stack, "Site", {
path: "path/to/site",
customDomain: "domain.com",
});

Redirect www to non-www (Route 53 domains)

new NextjsSite(stack, "Site", {
path: "path/to/site",
customDomain: {
domainName: "domain.com",
domainAlias: "www.domain.com",
},
});

Configuring domains across stages (Route 53 domains)

new NextjsSite(stack, "Site", {
path: "path/to/site",
customDomain: {
domainName:
scope.stage === "prod" ? "domain.com" : `${scope.stage}.domain.com`,
domainAlias: scope.stage === "prod" ? "www.domain.com" : undefined,
},
});

Configuring alternate domain names (Route 53 domains)

You can specify additional domain names for the site url. Note that the certificate for these names will not be automatically generated, so the certificate option must be specified. Also note that you need to manually create the Route 53 records for the alternate domain names.

import * as acm from "aws-cdk-lib/aws-certificatemanager";
import * as route53 from "aws-cdk-lib/aws-route53";
import * as route53Targets from "aws-cdk-lib/aws-route53-targets";

// Look up hosted zone
const hostedZone = route53.HostedZone.fromLookup(stack, "HostedZone", {
domainName: "domain.com",
});

// Create a certificate with alternate domain names
const certificate = new acm.DnsValidatedCertificate(stack, "Certificate", {
domainName: "foo.domain.com",
hostedZone,
region: "us-east-1",
subjectAlternativeNames: ["bar.domain.com"],
});

// Create site
const site = new NextjsSite(stack, "Site", {
path: "path/to/site",
customDomain: {
domainName: "foo.domain.com",
alternateNames: ["bar.domain.com"],
cdk: {
hostedZone,
certificate,
},
},
});

// Create A and AAAA records for the alternate domain names
const recordProps = {
recordName: "bar.domain.com",
zone: hostedZone,
target: route53.RecordTarget.fromAlias(
new route53Targets.CloudFrontTarget(site.cdk.distribution)
),
};
new route53.ARecord(stack, "AlternateARecord", recordProps);
new route53.AaaaRecord(stack, "AlternateAAAARecord", recordProps);

Importing an existing certificate (Route 53 domains)

import { Certificate } from "aws-cdk-lib/aws-certificatemanager";

new NextjsSite(stack, "Site", {
path: "path/to/site",
customDomain: {
domainName: "domain.com",
cdk: {
certificate: Certificate.fromCertificateArn(stack, "MyCert", certArn),
},
},
});

Note that, the certificate needs be created in the us-east-1(N. Virginia) region as required by AWS CloudFront.

Specifying a hosted zone (Route 53 domains)

If you have multiple hosted zones for a given domain, you can choose the one you want to use to configure the domain.

import { HostedZone } from "aws-cdk-lib/aws-route53";

new NextjsSite(stack, "Site", {
path: "path/to/site",
customDomain: {
domainName: "domain.com",
cdk: {
hostedZone: HostedZone.fromHostedZoneAttributes(stack, "MyZone", {
hostedZoneId,
zoneName,
}),
},
},
});

Configuring externally hosted domain

import { Certificate } from "aws-cdk-lib/aws-certificatemanager";

new NextjsSite(stack, "Site", {
path: "path/to/site",
cutomDomain: {
isExternalDomain: true,
domainName: "domain.com",
cdk: {
certificate: Certificate.fromCertificateArn(stack, "MyCert", certArn),
},
},
});

Note that the certificate needs be created in the us-east-1(N. Virginia) region as required by AWS CloudFront, and validated. After the Distribution has been created, create a CNAME DNS record for your domain name with the Distribution's URL as the value. Here are more details on configuring SSL Certificate on externally hosted domains.

Also note that you can also migrate externally hosted domains to Route 53 by following this guide.

Configuring the Lambda Functions

Configure the internally created CDK Lambda Function instance.

new NextjsSite(stack, "Site", {
path: "path/to/site",
defaults: {
function: {
timeout: 20,
memorySize: 2048,
permissions: ["sns"],
}
},
});

Permissions

You can attach a set of permissions to allow the Next.js API routes and Server Side rendering getServerSideProps to access other AWS resources.

const site = new NextjsSite(stack, "Site", {
path: "path/to/site",
});

site.attachPermissions(["sns"]);

Advanced examples

Using an existing S3 Bucket

import * as s3 from "aws-cdk-lib/aws-s3";

new NextjsSite(stack, "Site", {
path: "path/to/site",
cdk: {
bucket: s3.Bucket.fromBucketName(stack, "Bucket", "my-bucket"),
},
});

Configuring Lambda Functions

Configure the internally created CDK Lambda Function instance.

new NextjsSite(stack, "Site", {
path: "path/to/site",
defaults: {
function: {
timeout: 20,
memorySize: 2048,
permissions: ["sns"],
},
},
});

Reusing CloudFront cache policies

CloudFront has a limit of 20 cache policies per AWS account. This is a hard limit, and cannot be increased. Each NextjsSite creates 3 cache policies. If you plan to deploy multiple Next.js sites, you can have the constructs share the same cache policies by reusing them across sites.

import * as cloudfront from "aws-cdk-lib/aws-cloudfront";

const cachePolicies = {
staticCachePolicy: new cloudfront.CachePolicy(stack, "StaticCache", NextjsSite.staticCachePolicyProps),
imageCachePolicy: new cloudfront.CachePolicy(stack, "ImageCache", NextjsSite.imageCachePolicyProps),
lambdaCachePolicy: new cloudfront.CachePolicy(stack, "LambdaCache", NextjsSite.lambdaCachePolicyProps),
};

new NextjsSite(stack, "Site1", {
path: "path/to/site1",
cdk: {
cachePolicies,
}
});

new NextjsSite(stack, "Site2", {
path: "path/to/site2",
cdk: {
cachePolicies,
}
});

Reusing CloudFront image origin request policy

CloudFront has a limit of 20 origin request policies per AWS account. This is a hard limit, and cannot be increased. Each NextjsSite creates a new origin request policy by default. If you plan to deploy multiple Next.js sites, you can have the constructs share the same origin request policy by reusing them across sites.

import * as cloudfront from "aws-cdk-lib/aws-cloudfront";

const imageOriginRequestPolicy = new cloudfront.OriginRequestPolicy(stack, "ImageOriginRequest", NextjsSite.imageOriginRequestPolicyProps);

new NextjsSite(stack, "Site1", {
path: "path/to/site1",
cdk: {
imageOriginRequestPolicy,
}
});

new NextjsSite(stack, "Site2", {
path: "path/to/site2",
cdk: {
imageOriginRequestPolicy,
}
});

Constructor

new NextjsSite(scope, id, props)

Parameters

NextjsSiteProps

commandHooks.afterBuild?

Type : Array<string>

Commands to run after building the Next.js app. Commands are chained with &&, and they are run inside the Next.js app folder.

new NextjsSite(stack, "NextSite", {
path: "path/to/site",
commandHooks: {
afterBuild: ["npx next-sitemap"],
}
});

customDomain?

Type : string | NextjsDomainProps

The customDomain for this website. SST supports domains that are hosted either on Route 53 or externally. Note that you can also migrate externally hosted domains to Route 53 by following this guide.

new NextjsSite(stack, "Site", {
path: "path/to/site",
customDomain: "domain.com",
});
new NextjsSite(stack, "Site", {
path: "path/to/site",
customDomain: {
domainName: "domain.com",
domainAlias: "www.domain.com",
hostedZone: "domain.com"
},
});

defaults.function.memorySize?

Type : number

defaults.function.permissions?

Type : Permissions

defaults.function.runtime?

Type : "nodejs12.x" | "nodejs14.x" | "nodejs16.x"

Default : "nodejs16.x"

The runtime environment.

new NextjsSite(stack, "Function", {
path: "path/to/site",
runtime: "nodejs16.x",
})

defaults.function.timeout?

Type : number

disablePlaceholder?

Type : boolean

When running sst start, a placeholder site is deployed. This is to ensure that the site content remains unchanged, and subsequent sst start can start up quickly.

new NextjsSite(stack, "NextSite", {
path: "path/to/site",
disablePlaceholder: true,
});

An object with the key being the environment variable name.

new NextjsSite(stack, "NextSite", {
path: "path/to/site",
environment: {
API_URL: api.url,
USER_POOL_CLIENT: auth.cognitoUserPoolClient.userPoolClientId,
},
});

nextBinPath?

Type : string

Default : "./node_modules/.bin/next"

Path to the next executable, typically in node_modules. This should be used if next is installed in a non-standard location.

path

Type : string

Path to the directory where the website source is located.

waitForInvalidation?

Type : boolean

While deploying, SST waits for the CloudFront cache invalidation process to finish. This ensures that the new content will be served once the deploy command finishes. However, this process can sometimes take more than 5 mins. For non-prod environments it might make sense to pass in false. That'll skip waiting for the cache to invalidate and speed up the deploy process.

cdk.bucket?

Type : BucketProps | IBucket

Allows you to override default settings this construct uses internally to ceate the bucket

cdk.cachePolicies.imageCachePolicy?

Type : ICachePolicy

cdk.cachePolicies.lambdaCachePolicy?

Type : ICachePolicy

cdk.cachePolicies.staticCachePolicy?

Type : ICachePolicy

Override the default CloudFront cache policies created internally.

cdk.distribution?

Type : NextjsCdkDistributionProps

Pass in a value to override the default settings this construct uses to create the CDK Distribution internally.

cdk.imageOriginRequestPolicy?

Type : IOriginRequestPolicy

Override the default CloudFront image origin request policy created internally

cdk.regenerationQueue?

Type : QueueProps

Override the default settings this construct uses to create the CDK Queue internally.

Properties

An instance of NextjsSite has the following properties.

bucketArn

Type : string

The ARN of the internally created S3 Bucket.

bucketName

Type : string

The name of the internally created S3 Bucket.

customDomainUrl

Type : undefined | string

If the custom domain is enabled, this is the URL of the website with the custom domain.

distributionDomain

Type : string

The domain name of the internally created CloudFront Distribution.

distributionId

Type : string

The ID of the internally created CloudFront Distribution.

imageCachePolicyProps

Type : CachePolicyProps

The default CloudFront cache policy properties for images.

imageOriginRequestPolicyProps

Type : OriginRequestPolicyProps

The default CloudFront image origin request policy properties for Lambda@Edge.

lambdaCachePolicyProps

Type : CachePolicyProps

The default CloudFront cache policy properties for Lambda@Edge.

staticCachePolicyProps

Type : CachePolicyProps

The default CloudFront cache policy properties for static pages.

url

Type : string

The CloudFront URL of the website.

cdk.bucket

Type : Bucket

The internally created CDK Bucket instance.

cdk.certificate?

Type : ICertificate

The AWS Certificate Manager certificate for the custom domain.

cdk.distribution

Type : Distribution

The internally created CDK Distribution instance.

cdk.hostedZone?

Type : IHostedZone

The Route 53 hosted zone for the custom domain.

cdk.regenerationQueue

Type : Queue

The internally created CDK Queue instance.

Methods

An instance of NextjsSite has the following methods.

attachPermissions

attachPermissions(permissions)

Parameters

Attaches the given list of permissions to allow the Next.js API routes and Server Side rendering getServerSideProps to access other AWS resources.

Attaching permissions

const site = new NextjsSite(stack, "Site", {
path: "path/to/site",
});

site.attachPermissions(["sns"]);

NextjsDomainProps

alternateNames?

Type : Array<string>

Default : []

Specify additional names that should route to the Cloudfront Distribution. Note, certificates for these names will not be automatically generated so the certificate option must be specified.

domainAlias?

Type : string

Default : no alias configured

An alternative domain to be assigned to the website URL. Visitors to the alias will be redirected to the main domain. (ie. www.domain.com). Use this to create a www. version of your domain and redirect visitors to the root domain.

domainName

Type : string

The domain to be assigned to the website URL (ie. domain.com). Supports domains that are hosted either on Route 53 or externally.

hostedZone?

Type : string

Default : same as the domainName

The hosted zone in Route 53 that contains the domain. By default, SST will look for a hosted zone matching the domainName that's passed in. Set this option if SST cannot find the hosted zone in Route 53.

isExternalDomain?

Type : boolean

Default : false

Set this option if the domain is not hosted on Amazon Route 53.

cdk.certificate?

Type : ICertificate

Import the certificate for the domain. By default, SST will create a certificate with the domain name. The certificate will be created in the us-east-1(N. Virginia) region as required by AWS CloudFront. Set this option if you have an existing certificate in the us-east-1 region in AWS Certificate Manager you want to use.

cdk.hostedZone?

Type : IHostedZone

Import the underlying Route 53 hosted zone.

NextjsCdkDistributionProps

defaultBehavior?

Type :