DynamoDB streams

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Create a DynamoDB table, enable streams, and subscribe to it with a function.

sst.config.ts

const table = new sst.aws.Dynamo("MyTable", {
  fields: {
    id: "string",
  },
  primaryIndex: { hashKey: "id" },
  stream: "new-and-old-images",
});
table.subscribe("MySubscriber", "subscriber.handler", {
  filters: [
    {
      dynamodb: {
        NewImage: {
          message: {
            S: ["Hello"],
          },
        },
      },
    },
  ],
});

const creator = new sst.aws.Function("MyCreator", {
  handler: "creator.handler",
  link: [table],
  url: true,
});

const reader = new sst.aws.Function("MyReader", {
  handler: "reader.handler",
  link: [table],
  url: true,
});

subscriber.ts

export const handler = async (event) => {
  console.log(JSON.stringify(event, null, 2));
  return "ok";
};

creator.ts

import { Resource } from "sst";
import { DynamoDBClient, PutItemCommand } from "@aws-sdk/client-dynamodb";
const client = new DynamoDBClient();

export const handler = async (event) => {
  await client.send(
    new PutItemCommand({
      TableName: Resource.MyTable.name,
      Item: {
        id: { S: Date.now().toString() },
        message: { S: "Hello" },
      },
    })
  );

  return {
    statusCode: 200,
    body: JSON.stringify({ status: "sent" }, null, 2),
  };
};

reader.ts

import { Resource } from "sst";
import { DynamoDBClient, ScanCommand } from "@aws-sdk/client-dynamodb";
const client = new DynamoDBClient();

export const handler = async () => {
  const result = await client.send(
    new ScanCommand({
      TableName: Resource.MyTable.name,
    })
  );

  return {
    statusCode: 200,
    body: JSON.stringify(result.Items, null, 2),
  };
};

View the full example.