AWS Certified Developer Associate Practice Test (DVA-C02)

The correct service is designed to automate code reviews and provide recommendations for enhancing code quality, including identifying security vulnerabilities. The other options listed are services that serve different purposes: orchestration of resource creation, tracking resource configurations and changes, and logging API activity across an account respectively.

The appropriate service for the creation and administration of encryption keys in the cloud is Key Management Service (KMS), which provides options to both create your own encryption keys and configure them for automatic rotation. Utilizing KMS keys offers the capability to fulfill the need for encryption at rest within S3 while also adhering to the company's guidelines for regular key rotation. The reliance on the platform's own managed keys would preclude direct control and rotation management. Certificate Manager's primary use case involves issuing certificates for TLS, not storage encryption, while CloudHSM is tailored for specific compliance requirements and does not innately manage automatic key rotation.

The AWS Serverless Application Model (AWS SAM) CLI can run Lambda functions inside Docker containers that replicate the AWS Lambda execution environment. Developers can use commands such as sam local invoke and sam local start-api to test and debug code locally, saving time and avoiding deployment costs. The other options do not provide local Lambda emulation.

AWS Secrets Manager supports the automatic rotation of secrets - a feature that benefits the security of application environments by regularly changing secret values. It also integrates with RDS databases, allowing the use of Lambda functions to define custom rotation strategies without causing downtime. The other options are either not designed for secrets management or do not provide the same level of automation and integration capabilities.

CodeCommit is the correct answer because it is designed to securely store and version your code in the cloud, supporting the collaboration of multiple developers with private Git repositories. While CodePipeline does integrate with source control services, it primarily serves as a continuous delivery service to automate the release process, but does not store code. CodeBuild compiles source code, runs tests, and produces software packages, but does not manage source control repositories. Lastly, Elastic Container Registry (ECR) is a Docker container registry service used for storing, managing, and deploying Docker container images, and is not used for version controlling source code.

The most efficient way to revert to the previous stable release under the described deployment strategy is to switch the production traffic back to the older environment that's still operational with the last stable release. This action provides the quickest rollback with minimal downtime. Redeploying the previous release or setting up a new environment can introduce delays or further complications. Using function versions and aliases is not applicable to the described scenario, which implies a non-serverless environment.

In the scenario given, a third-party service that is intermittently unavailable would benefit from implementing retries with exponential backoff and jitter. The exponential backoff method systematically increases the wait time between retries after a failed attempt to call the third-party service. Adding jitter reduces the probability that multiple instances of your application will attempt to retry at the same moment, avoiding simultaneous retries that can lead to the 'thundering herd' problem when the service recovers. This can be particularly useful for distributed systems that rely on external services to ensure they can continue to operate effectively during transient outages. Using a circuit breaker does address an unreliable service, but the question specifically asks for a pattern that involves retry logic. Increasing read and write capacity or immediate recursive retries do not address the underlying issue of the service's unpredictability and may worsen it by potentially overloading the service when it comes back online.

Implementing a blue/green deployment permits the switch from a current version of the application to a new one without any downtime by routing traffic between two identical environments that are running different versions of the application. This ensures that the live version is untouched until the new one is ready, allowing quick rollbacks if required. Using alias and version management in serverless compute environments does not inherently assure zero downtime for web applications. Configuration of instance scaling is targeted towards resource optimization rather than deployment strategies. An in-place deployment updates the existing environment, which naturally involves a period of downtime.

AWS X-Ray is a service that helps developers analyze and debug distributed applications, such as those built using a microservices architecture. One of its features is the ability to add annotations to traces. Annotations are key-value pairs that provide additional details about the work done by a service, such as the method's inputs and outputs or any relevant state information. Knowing how to use AWS X-Ray to add annotations is crucial as it enables efficient root cause analysis when troubleshooting issues.

The correct solution is to use AWS Secrets Manager. This service is specifically designed for securely storing, managing, and retrieving secrets like database credentials, and it offers native support for automatic credential rotation for supported databases like Amazon RDS. Storing sensitive data in Lambda environment variables is not recommended as they can be inadvertently exposed in logs or accessed by compromised dependencies. Embedding credentials in source code is a major security risk and should always be avoided. While AWS Systems Manager Parameter Store can store credentials as SecureString parameters, it does not offer the same built-in, automated rotation capabilities as Secrets Manager, making Secrets Manager the superior choice for this use case.

Including meaningful custom log messages at various points in the application code allows developers and operators to understand the application's behavior and state, which is essential for diagnosing issues and optimizing performance. It provides context that can make debugging and monitoring more effective by shining a light on the application's internal processes at critical moments.

Using JSON format for logs would ensure that each log entry is consistent and can be easily parsed and queried. JSON is a widely-known format which can be directly used with services like Amazon CloudWatch Logs Insights to run complex queries. By contrast, CSV lacks a self-describing format and the absence of keys can make it harder to interpret. Plain text logs lack structured data, making them difficult to query programmatically. Although XML is also structured, it is more verbose and not as readily queryable within AWS services as JSON.

The developer should implement a Lambda authorizer, which is a way to handle custom authorization logic before granting access to the serverless function endpoint. The Lambda authorizer can verify the validity of the token and determine if the request should be allowed or denied. This approach is particularly useful in serverless architectures where application components are loosely coupled, and an external identity provider manages user authentication. This verification is performed within the AWS environment without making a round trip to the external identity provider. On the contrary, IAM roles are for access management within AWS services and resources, not for validating tokens directly. Resource-based policies define permissions for AWS resources, but they do not provide a method for validating bearer tokens. Client-side certificates are used for mutual TLS (mTLS) authentication but do not apply to the scenario involving verification of tokens provided by an external identity provider.

Amazon Cognito with identity pools allows you to grant your users temporary, limited-privilege credentials to access AWS resources. This service can federate with external identity providers like social media platforms and corporate directories, exchanging their authentication tokens for temporary permissions in your environment. While Amazon Cognito user pools handle user management and authentication, they do not support direct federation for resource access. The IAM service is responsible for defining roles and permissions but does not handle direct identity federation. Similarly, STS is used for granting temporary credentials but is not directly responsible for federating with identity providers in the context of your application's users.

The HTTP status code 403 Forbidden is returned by a server to indicate that the request was valid, but the server is refusing action. The server understands the request, but it won't fulfill it due to client-side issues, such as insufficient permissions. A 401 Unauthorized error code would imply that proper authentication is required and has either not been provided or is being denied; this scenario did not specifically mention an issue with authentication credentials. Conversely, a 404 Not Found would suggest the requested resource could not be found, and a 500 Internal Server Error would imply a server-side error, which does not fit the description of understanding but refusing the request.