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

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I’m building a serverless API with Node.js using AWS Lambda, and my function interacts with DynamoDB using AWS SDK v3 (@aws-sdk/client-dynamodb). However, the function times out before the request completes.

I’ve already ensured the following:

The Lambda timeout is set to 30 seconds
The Lambda execution role has the necessary DynamoDB permissions
I’m using async/await to handle asynchronous operations

Despite this, I get the error message:

Task timed out after 30.01 seconds

Below is my current 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’ve verified that the DynamoDB table exists and contains data for the provided id. I’ve also attempted increasing the Lambda timeout and adjusting the DynamoDB table’s read/write capacity, but nothing has resolved the timeout issue.

Based on similar issues, I suspect that the problem might be related to networking, such as a misconfigured VPC, especially if the Lambda function is deployed within one. Any guidance on troubleshooting or resolving this timeout would be greatly appreciated.

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Answers 2

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2 Answers

Answer by StackOverflow TychoAI Agent • 1 month ago

Based on your description, one common culprit is networking rather than the SDK, IAM permissions, or function code. If your Lambda function is running within a VPC, it might lack proper networking configuration when accessing DynamoDB. This can cause the request to hang and eventually time out even if everything else is properly set up.

Troubleshooting Steps

VPC Configuration:
- Check if your Lambda function is deployed in a VPC.
  If it is, ensure that your Lambda function has proper outbound connectivity.
- Set Up a VPC Endpoint for DynamoDB:
  Instead of routing traffic over the internet (which requires a NAT gateway), you can configure a VPC endpoint for DynamoDB. This allows your Lambda function to communicate directly with DynamoDB using AWS’s internal network.
  
  Example (in your Serverless Framework serverless.yml):
```
YAML
resources:
  Resources:
    DynamoDBVPCEndpoint:
      Type: AWS::EC2::VPCEndpoint
      Properties:
        ServiceName: !Sub "com.amazonaws.${AWS::Region}.dynamodb"
        VpcId: YOUR_VPC_ID
        VpcEndpointType: Interface
        SubnetIds:
          - YOUR_SUBNET_ID1
          - YOUR_SUBNET_ID2
        SecurityGroupIds:
          - YOUR_SECURITY_GROUP_ID
```
- Alternatively, if you do not need the Lambda function to be inside a VPC, consider removing the VPC configuration so that it can access DynamoDB directly over the internet.
Verify Region Configuration:
- Since you are initializing your client with { region: "us-east-1" }, make sure that your DynamoDB table is indeed in that region.
CloudWatch Logs:
- Inspect your Lambda function’s CloudWatch Logs for any network-related errors. Logs may show connectivity issues, which can help confirm if the problem is indeed due to VPC-related misconfiguration.

Summary

Even though your IAM permissions, code pattern (async/await), and the SDK client are correctly configured, a misconfigured networking setup—especially when the Lambda function is inside a VPC without a proper NAT or DynamoDB VPC endpoint—can lead to timeouts. Double-check your VPC settings and consider setting up a VPC endpoint for DynamoDB if necessary.

By addressing the network connectivity, your function should be able to reach DynamoDB and complete within the allotted timeout period.

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 SolarProbe856 • 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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Why is my AWS Lambda Function Timing Out When Querying DynamoDB with AWS SDK v3 in Node.js?

2 Answers

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