What is the process for replicating and searching DynamoDB data in Amazon OpenSearch Service in TypeScript

Question

Pulumi · Accepted Answer

Replicating and searching data from Amazon DynamoDB into Amazon OpenSearch Service (formerly known as Elasticsearch Service) requires several steps. In this context, replication is generally set up using AWS Lambda to listen to DynamoDB Streams and index the data into OpenSearch. However, because of the complexity and customization required for a full solution, I'll outline the core Pulumi resources and the high-level architecture to set this up. The overall process includes creating a DynamoDB table, setting up a streaming feature on that table, creating an OpenSearch domain, and configuring a Lambda function to process changes from the DynamoDB stream and post them to OpenSearch.

Below is a TypeScript program in Pulumi that sets up these AWS resources:

1. **DynamoDB Table with Stream Enabled**: This is for storing your data and providing a Stream of changes.
2. **OpenSearch Service Domain**: This is where the data from DynamoDB will be indexed and made searchable.
3. **IAM Roles and Policies**: These are needed to give permissions for Lambda to access DynamoDB Streams and post to OpenSearch.

Here's the foundational Pulumi code that sets up these components:

```typescript
import * as aws from "@pulumi/aws";
import * as pulumi from "@pulumi/pulumi";

// Create a DynamoDB table with stream enabled
const table = new aws.dynamodb.Table("my-table", {
    attributes: [
        { name: "Id", type: "S" },
    ],
    hashKey: "Id",
    streamEnabled: true,
    streamViewType: "NEW_AND_OLD_IMAGES",
});

// Create an Amazon OpenSearch Service domain
const domain = new aws.opensearch.Domain("my-domain", {
    domainName: "my-domain",
    clusterConfig: {
        instanceType: "t2.small.search"
    },
    ebsOptions: {
        ebsEnabled: true,
        volumeSize: 10,
    },
});

// Assume this Lambda function code will read from DynamoDB Streams and index documents in OpenSearch
const lambdaFunction = new aws.lambda.Function("my-lambda-function", {
    code: new pulumi.asset.AssetArchive({
        ".": new pulumi.asset.FileArchive("./lambda"),
    }),
    runtime: aws.lambda.NodeJS12dXRuntime,
    handler: "index.handler",
    role: lambdaRole.arn,
    environment: {
        variables: {
            OPENSEARCH_ENDPOINT: domain.endpoint,
        },
    },
    eventSourceMappings: [{
        eventSourceArn: table.streamArn,
        functionName: lambdaFunction.name,
    }],
});

// IAM role for Lambda execution and policies to allow access to DynamoDB Streams and OpenSearch
const lambdaRole = new aws.iam.Role("lambda-exec-role", {
    assumeRolePolicy: {
        Version: "2012-10-17",
        Statement: [{
            Action: "sts:AssumeRole",
            Effect: "Allow",
            Principal: {
                Service: "lambda.amazonaws.com",
            },
        }],
    },
});

// IAM policy attachment for Lambda to access DynamoDB Streams
new aws.iam.RolePolicyAttachment("dynamodb-access", {
    role: lambdaRole,
    policyArn: aws.iam.ManagedPolicy.AWSLambdaDynamoDBExecutionRole,
});

// IAM policy attachment for Lambda to access OpenSearch
const lambdaOpenSearchPolicy = new aws.iam.Policy("lambda-opensearch-policy", {
    policy: {
        Version: "2012-10-17",
        Statement: [{
            Action: ["es:ESHttpGet", "es:ESHttpPut"],
            Effect: "Allow",
            Resource: `${domain.arn}/*`,
        }],
    },
});

// Attach the OpenSearch policy to Lambda execution role
new aws.iam.RolePolicyAttachment("lambda-opensearch-policy-attachment", {
    role: lambdaRole,
    policyArn: lambdaOpenSearchPolicy.arn,
});

// Export relevant resources
export const dynamoTableName = table.name;
export const openSearchDomainEndpoint = domain.endpoint;
```

This code sets up the infrastructure mentioned above with the following steps:

- **DynamoDB Table**: Creates a new DynamoDB table with the primary key as `Id` of type String and a stream that captures both new and old images of items.
  
- **OpenSearch Domain**: Sets up an Amazon OpenSearch Service domain with a small instance type, which is suitable for development or small workloads.

- **IAM Roles and Policies**: Provisions an execution role for the Lambda function and attaches managed and custom policies that give the function permissions to read from DynamoDB streams and access the OpenSearch domain.

- **Lambda Function**: Defines an AWS Lambda function (you'll have to provide the actual implementation in the `./lambda` directory) that will be triggered by changes in the DynamoDB stream, process these records, and then post them to the OpenSearch Service for indexing.

Make sure you replace `'./lambda'` with the location of your Lambda function's code and `'index.handler'` with the actual handler in your code.

Remember that you would need to have AWS credentials configured for Pulumi, the `aws` plugin installed, and you would need to write the Lambda function's code that processes the DynamoDB Stream and indexes it into OpenSearch.

Setting up such a data pipeline can be complex and might require additional error handling, retry mechanisms, and configuration, which need to be implemented in the Lambda's logic. This program provides you with the AWS infrastructure to start building out the replication and search functionality.