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Difficulty: MediumDebugging Lambda Execution and Configuration Issues

A developer is troubleshooting an AWS Lambda function that processes customer orders. The Lambda function is configured to run inside a custom VPC in two private subnets to access an Amazon RDS database securely. During testing, the function times out when attempting to connect to an external payment processor's HTTP endpoint over the internet. Additionally, under load, the Lambda function frequently times out because it establishes a new database connection during each invocation, quickly exhausting database resources.

Which combination of actions will resolve these issues? (Select TWO.)

  1. Configuring a NAT gateway in a public subnet, and updating the route tables of the private subnets to route outbound internet traffic (0.0.0.0/0) through the NAT gateway.Answer
  2. Declaring the database connection client outside of the Lambda handler function to enable execution context reuse across warm starts.Answer
  3. C
    Attaching an Internet Gateway directly to the private subnets where the Lambda function is deployed, and assigning public IP addresses to the function configuration.
  4. D
    Moving the Lambda function to a public subnet in the VPC to allow direct route access to the Internet Gateway for external communication.
  5. E
    Re-initializing the database connection client inside the Lambda handler and executing a connection close method at the end of each invocation.

Answer

The correct options are configuring a NAT gateway in a public subnet and routing the private subnet's traffic through it, and declaring the database connection client outside of the handler function to reuse the execution context.
The correct options resolve both issues. Routing internet-bound traffic from private subnets through a NAT gateway in a public subnet allows the Lambda function to communicate with the external payment API. Declaring the database client outside the handler code ensures that the database connection is reused across invocations, mitigating connection overhead and latency.

Step-by-Step Solution

1
Address the external payment processor connection timeouts.
Determine that Lambda functions in private subnets require a NAT gateway or VPC endpoint to access the public internet.
Since the external API is on the internet, a NAT gateway must be set up in a public subnet, and the private subnet route tables must be updated to route outbound traffic through it.
2
Address the database resource exhaustion and execution timeouts under load.
Move the database connection initialization code out of the Lambda handler block to global scope.
This allows subsequent warm executions of the function to reuse the existing database connection pool instead of repeatedly opening and closing sockets, resolving execution timeouts and database overload.

Key Concept

VPC networking configuration for outbound Lambda internet access and database connection optimization using execution context reuse.
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Topics

Debugging Lambda Execution and Configuration Issues

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