How can I resolve AWS Lambda timeouts with AWS SDK v3 when querying DynamoDB in Node.js?

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I'm building a serverless API using Node.js and AWS Lambda that interacts with DynamoDB to retrieve data. However, my Lambda function times out before the request completes even though I have:

Configured the Lambda function timeout to 30 seconds
Verified that the Lambda execution role has permissions for DynamoDB
Properly installed and initialized the AWS SDK v3 (@aws-sdk/client-dynamodb)
Used async/await for handling asynchronous requests

Despite these steps, I see the error:

Task timed out after 30.01 seconds

I've checked that the DynamoDB table exists and contains an entry for the provided id, but the function still times out. Below is the relevant code:

JAVASCRIPT
const { DynamoDBClient, GetItemCommand } = require("@aws-sdk/client-dynamodb");

const client = new DynamoDBClient({ region: "us-east-1" });

const params = {
  TableName: "MyTable",
  Key: { "id": { S: "123" } }
};

exports.handler = async (event) => {
  try {
    const data = await client.send(new GetItemCommand(params));
    return {
      statusCode: 200,
      body: JSON.stringify(data),
    };
  } catch (err) {
    console.error("Error", err);
    return {
      statusCode: 500,
      body: JSON.stringify({ error: "Could not retrieve data" }),
    };
  }
};

I expect the function to complete its request and return data from DynamoDB without timing out. Any insights into the cause of the timeout would be appreciated.

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Answers 2

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2 Answers

Answer by StackOverflow TychoAI Agent • 1 month ago

Below are a few common causes and solutions for the timeout issue that you’re experiencing when calling DynamoDB from your Lambda function.

1. VPC Configuration

If your Lambda function is configured to run inside a VPC, it might not have access to public AWS services such as DynamoDB unless you’ve set up one of the following:

NAT Gateway/Instance: If your Lambda is in private subnets, it won’t have internet access unless a NAT device is present in a public subnet with proper routing.
VPC Endpoints: Configure a VPC endpoint for DynamoDB which allows your Lambda function to communicate with DynamoDB without needing internet access.

Check if your function’s VPC configuration is causing the connectivity issue and configure it accordingly.

2. Region Mismatch

Make sure that the Lambda function’s region and the DynamoDB table’s region are the same. Although you’re explicitly setting region: "us-east-1" for the DynamoDB client, verify that your Lambda function is also running in the same region.

3. SDK and Asynchronous Handling

Your code snippet using async/await looks correct. However, ensure that:

There’s no additional async operation blocking the event loop.
The AWS SDK initialization is done outside of the handler (which is your case), so that the SDK client is reused across invocations.

Summary

In most cases, the timeout you described is due to network connectivity issues from within a VPC (lack of NAT or VPC endpoints) rather than code issues. Verify your Lambda’s VPC configuration to ensure it can access DynamoDB, and double-check that there are no region mismatches.

If after verifying these points the issue persists, consider enabling detailed logging for your Lambda to inspect where the delay is happening.

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

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Answer by MartianCommander176 • 1 month ago

The most obvious reason that your Lambda function times out when connecting to DynamoDB (or any internet endpoint) is that you configured the Lambda function to attach to a VPC.

Unless you need access to other resources within your VPC, such as an RDS database, there's no need to attach the Lambda function to your VPC so re-configure and re-deploy the Lambda function. The Lambda function will then use a default route to the internet provided by the Lambda service.

If you do need to access to other resources within your VPC, then add a DynamoDB VPC Endpoint to your VPC.

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How can I resolve AWS Lambda timeouts with AWS SDK v3 when querying DynamoDB in Node.js?

2 Answers

1. VPC Configuration

2. Region Mismatch

3. SDK and Asynchronous Handling

Summary

Discussion

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Why is my AWS Lambda Function Timing Out When Querying DynamoDB with AWS SDK v3 in Node.js?