We are now going to start creating our infrastructure in SST using AWS CDK. Starting with DynamoDB.

Create a Stack

Add the following to a new file in stacks/StorageStack.js.

import * as sst from "@serverless-stack/resources";

export default class StorageStack extends sst.Stack {
  // Public reference to the table

  constructor(scope, id, props) {
    super(scope, id, props);

    // Create the DynamoDB table
    this.table = new sst.Table(this, "Notes", {
      fields: {
        userId: sst.TableFieldType.STRING,
        noteId: sst.TableFieldType.STRING,
      primaryIndex: { partitionKey: "userId", sortKey: "noteId" },

Let’s quickly go over what we are doing here.

We are creating a new stack in our SST app. We’ll be using it to create all our storage related infrastructure (DynamoDB and S3). There’s no specific reason why we are creating a separate stack for these resources. It’s only meant as a way of organizing our resources and illustrating how to create separate stacks in our app.

We are using SST’s Table construct to create our DynamoDB table.

It has two fields:

  1. userId: The id of the user that the note belongs to.
  2. noteId: The id of the note.

We are then creating an index for our table.

Each DynamoDB table has a primary key. This cannot be changed once set. The primary key uniquely identifies each item in the table, so that no two items can have the same key. DynamoDB supports two different kinds of primary keys:

  • Partition key
  • Partition key and sort key (composite)

We are going to use the composite primary key (referenced by primaryIndex in code block above) which gives us additional flexibility when querying the data. For example, if you provide only the value for userId, DynamoDB would retrieve all of the notes by that user. Or you could provide a value for userId and a value for noteId, to retrieve a particular note.

We are also exposing the Table that’s being created publicly.

// Public reference to the table

This’ll allow us to reference this resource in our other stacks.

Remove Template Files

The Hello World API that we previously created, can now be removed. We can also remove the files that came with the starter template.

To remove the starter stack, run the following from your project root.

$ npx sst remove my-stack

This will take a minute to run.

Also remove the template files.

$ rm stacks/MyStack.js src/lambda.js

Add to the App

Now let’s add our new stack to the app.

Replace the stacks/index.js with this.

import StorageStack from "./StorageStack";

export default function main(app) {
  new StorageStack(app, "storage");

Deploy the App

If you switch over to your terminal, you’ll notice that you are being prompted to redeploy your changes. Go ahead and hit ENTER.

Note that, you’ll need to have sst start running for this to happen. If you had previously stopped it, then running npx sst start will deploy your changes again.

You should see something like this at the end of the deploy process.

Stack dev-notes-storage
  Status: deployed

The Stack name above of dev-notes-storage is a string derived from your ${stageName}-${appName}-${stackName}. Your appName is defined in the name field of your sst.json file and your stackName is the label you choose for your stack in `stacks/index.js’.

Now that our database has been created, let’s create an S3 bucket to handle file uploads.