DynamoDB Local Demo

A minimal template repository about AWS tools for working with a local DynamoDB, NoSQL Workbench, and a Lambda function.

This is part of the Medium article AWS NoSQL Workbench & DynamoDB Local which you can view for free.

Requirements

• Docker Compose
• AWS NoSQL Workbench (Optional)
• AWS CLI (Optional)
• A reasonable amount of free disk space for Docker images.

Docker Compose Services

• dynamodb-local
  • This is the local DynamoDB service without pre-existing data.
  • Accessible from the endpoint http://localhost:8000 when using the AWS CLI or SDK.
  • For the rest of the services, the endpoint is http://dynamodb-local:8000.
  • Uses amazon/dynamodb-local:1.17.0 from October 12, 2021 as the base image. See amazon/dynamodb-local.
• cli
  • This service creates a table in the dynamodb-local service using ./cli/create-table.sh along with a GSI defined in ./cli/gsi.json.
  • After ./cli/create-table.sh executes, this service exits.
  • Uses amazon/aws-cli:2.3.6 from November 12, 2021 as the base image. See amazon/aws-cli.
• function
  • A Lambda function you can POST to from http://localhost:9000/2015-03-31/functions/function/invocations. See Invoke Lambda Function.
  • Written in Node.js.

Setup

Provided you've got Docker installed and running, spin up the services from docker-compose.yml.

cd ./dynamodb-local-demo/
docker-compose up

The following events should happen.

1. dynamodb-local service starts.
2. cli service creates the DemoTable and GSI1Index.
3. cli service exits gracefully.
4. function service starts.

Invoke Lambda Function

The function can be invoked using curl as below.

curl --location --request POST 'http://localhost:9000/2015-03-31/functions/function/invocations' \
--header 'Content-Type: application/json' \
--data-raw '{
    "Item": {
        "Title": "Hello, world.",
        "Author": "John Doe, Jane Doe",
        "ReleaseDate": "2021/11/18",
        "ISBN10": "1234567890",
        "Version": "2"
    }
}'

If you get a 200 response, you can verify the new item you've added by from the Operation builder menu of the NoSQL Workbench.

For DemoTable and with the way the function service was written, a book's uniqueness depends on its ISBN10 and ReleaseDate values. If a combination of these values were already submitted, the function should return a 500 response with a ConditionalCheckFailedException message. See Error Handling with DynamoDB.

Books are suffixed by Book and are automatically prefixed with a number inclusively between 1 and 200. This numeric prefix is computed from the ISBN10 value for partitioning. See Using Write Sharding to Distribute Workloads Evenly.