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Zorluk: OrtaModernizing Workloads with Serverless Architectures (Lambda and API Gateway)

An enterprise is modernizing a legacy, high-volume batch processing and reporting workload by migrating it to a serverless architecture on AWS. The solution uses an Amazon API Gateway Regional REST API backed by AWS Lambda functions that read from and write to an Amazon Aurora PostgreSQL database. During peak load tests, the Lambda functions throttle other critical applications in the same AWS region, and outbound calls from Lambda to external verification APIs occasionally fail due to NAT gateway availability issues in a single Availability Zone. Which combination of architectural modifications will resolve these issues while maintaining high availability and security best practices? (Select TWO.)

  1. Configure reserved concurrency on the high-volume batch processing Lambda function to limit its maximum concurrent executions and protect other critical applications.Cevap
  2. Deploy NAT Gateways in multiple Availability Zones and update the route tables of the private subnets containing the Lambda functions to route outbound traffic through the local NAT Gateway in each zone.Cevap
  3. C
    Configure provisioned concurrency on the batch processing Lambda function to guarantee baseline execution capacity without setting a maximum ceiling, allowing it to scale dynamically to consume the entire regional concurrency pool.
  4. D
    Route all Lambda egress traffic through a single NAT Gateway deployed in a single Availability Zone to centralize traffic tracking and reduce active NAT Gateway hourly charges.
  5. E
    Configure the Lambda functions to encrypt sensitive application configuration files using the AWS-managed KMS key for Lambda (aws/lambda) and modify the key policy to delegate decryption permissions to a secondary auditing account.

Cevap

Configure reserved concurrency on the high-volume batch processing Lambda function to limit its concurrent executions, and deploy NAT Gateways across multiple Availability Zones to ensure redundant egress paths.
Configuring reserved concurrency on the high-volume batch processing function establishes a hard limit on the number of concurrent executions it can consume. This prevents the function from exhausting the regional concurrency pool, ensuring that other critical functions in the same region remain operational. Additionally, deploying NAT Gateways in multiple Availability Zones and configuring the corresponding subnet route tables ensures high availability and redundancy for outbound connections to external APIs, preventing single-AZ failures from disrupting egress traffic.

Adım Adım Çözüm

1
Analyze the cause of regional function throttling.
The high-volume Lambda function dynamically scales to consume the shared regional concurrency limit (default 1,000), which starves other critical applications.
A hard limit must be set using reserved concurrency to isolate and protect the shared regional execution pool.
2
Evaluate the egress networking path for outbound API calls.
Egress calls fail when a single NAT Gateway experiences issues or its Availability Zone is degraded.
To ensure reliable external API communication, NAT Gateways must be distributed across multiple Availability Zones, and route tables must be updated accordingly.
3
Assess key policy permissions for environment encryption.
AWS-managed keys do not permit key policy edits for cross-account access delegation.
This rules out the option attempting to modify the policy of the aws/lambda key, confirming that customer-managed keys are required for custom policies.

Anahtar Kavram

Mitigating resource exhaustion through Lambda reserved concurrency, and ensuring outbound network redundancy using multi-AZ NAT Gateways.
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Modernizing Workloads with Serverless Architectures (Lambda and API Gateway)

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