Build an API with SST
Create and deploy a serverless API in AWS with SST.
We are going to build a serverless API, add an S3 Bucket for file uploads, and deploy it to AWS using SST.
Before you get started:
1. Create a Node.js app
Let’s start by creating our app.
mkdir my-ts-app && cd my-ts-appnpm init -y
Init SST
Now let’s initialize SST in our app. Make sure you have the CLI installed.
sst init
This’ll create a sst.config.ts
file in your project root.
2. Add an API
Let’s add an API using Amazon API Gateway. Update your sst.config.ts
.
async run() { new sst.aws.ApiGatewayV2("MyApi") .route("GET /", "index.upload") .route("GET /latest", "index.latest");}
We are adding two routes, one for uploading an image and another for getting the latest uploaded image.
Start dev mode
Start your app in dev mode. This runs your functions Live.
sst dev
This will give you the URL of your API.
✔ Complete MyApi: https://y9ink9nh96.execute-api.us-east-1.amazonaws.com
3. Add an S3 Bucket
Let’s add a public
S3 Bucket for file uploads. Update your sst.config.ts
.
const bucket = new sst.aws.Bucket("MyBucket", { public: true});
Link the bucket
Now, link the bucket to the API routes.
new sst.aws.ApiGatewayV2("MyApi") .route("GET /", { link: [bucket], handler: "index.upload" }) .route("GET /latest", { link: [bucket], handler: "index.latest" });
4. Upload a file
We want the /
route of our API to generate a pre-signed URL to upload a file to our S3 Bucket. Create an index.ts
file and add the following.
export async function upload() { const command = new PutObjectCommand({ Key: crypto.randomUUID(), Bucket: Resource.MyBucket.name, });
return { statusCode: 200, body: await getSignedUrl(s3, command), };}
5. Download a file
We want the /latest
route of our API to generate a pre-signed URL to download the last uploaded file in our S3 Bucket. Add this to your index.ts
file.
export async function latest() { const objects = await s3.send( new ListObjectsV2Command({ Bucket: Resource.MyBucket.name, }) );
const latestFile = objects.Contents!.sort( (a, b) => (b.LastModified?.getTime() ?? 0) - (a.LastModified?.getTime() ?? 0) )[0];
const command = new GetObjectCommand({ Key: latestFile.Key, Bucket: Resource.MyBucket.name, });
return { statusCode: 302, headers: { Location: await getSignedUrl(s3, command), }, };}
Add the relevant imports.
import { Resource } from "sst";import { getSignedUrl } from "@aws-sdk/s3-request-presigner";import { S3Client, GetObjectCommand, PutObjectCommand, ListObjectsV2Command,} from "@aws-sdk/client-s3";
const s3 = new S3Client({});
And install the npm packages.
npm install sst@ion @aws-sdk/client-s3 @aws-sdk/s3-request-presigner
Test your app
Let’s try uploading a file from your project root. Make sure to use your API URL.
curl --upload-file package.json "$(curl https://y9ink9nh96.execute-api.us-east-1.amazonaws.com)"
Now head over to https://y9ink9nh96.execute-api.us-east-1.amazonaws.com/latest
in your browser and it’ll download the file you just uploaded.
6. Deploy your app
Now let’s deploy your app.
sst deploy
Connect the console
As a next step, you can manage your app and view issues in the SST Console.
You can create a free account and connect it to your AWS account.