Developer - Associate Practice Questions

Amazon Cognito User Pools have built-in functionality to send emails for various events, including user sign-up and verification. A developer can customize the message templates directly in the Cognito console or via the API, which is the simplest way to send a welcome email.

Cognito Lambda triggers allow developers to run custom logic in response to specific lifecycle events. The Post Authentication trigger is invoked after a user successfully signs in. A developer can write a Lambda function that receives user data from the event and makes an API call to the custom analytics service.

The standard method for packaging a Lambda function with its dependencies is to install the dependencies into the root directory of the project alongside the function code. In an AWS CodeBuild environment, this is achieved by adding a command to the buildspec.yml file. For Python, pip install -r requirements.txt -t . installs the libraries listed in requirements.txt into the current directory (.). The subsequent build step would then create a zip archive of the entire directory, which becomes the deployment package.

AWS X-Ray is a distributed tracing service that helps developers analyze and debug production, distributed applications. It provides an end-to-end view of requests as they travel through an application, showing a map of the application's underlying components. By instrumenting the application with the X-Ray SDK, the developer can generate trace data, view a service map to identify bottlenecks, and drill down into specific traces to see the latency of each downstream call.

The correct sequence for envelope encryption is: 1. Request a data key from KMS. The GenerateDataKey operation returns both a plaintext version of the key and a version encrypted under the specified KMS Customer Master Key (CMK). 2. Use the plaintext key to perform encryption locally within your application. 3. Store the resulting ciphertext along with the encrypted data key. You need the encrypted data key to decrypt the data later. 4. Erase the plaintext data key from memory as soon as possible to minimize its exposure.

The sam local invoke command allows a developer to run a single invocation of a Lambda function locally. It runs the function code in a Docker container that simulates the Lambda runtime environment. The developer can pass an event payload to the function using the -e or --event flag, making it ideal for unit and integration testing before deployment.

In AWS Lambda, CPU power is allocated proportionally to the amount of memory configured. Image processing is a CPU-intensive task. By increasing the memory, the developer also increases the available vCPU, which will speed up the processing of larger images and likely resolve the timeout issue. This is more effective than just increasing the timeout, as it addresses the root cause of the slow performance. AWS Lambda Power Tuning is a tool that can help find the optimal memory setting.

The best practice is to use a single Infrastructure as Code (IaC) template and manage environment-specific configurations separately. AWS CodePipeline's AWS CloudFormation deploy action allows specifying a parameter override file. The developer can create staging-params.json and production-params.json files to define stage-specific variables (like Lambda function names, memory sizes, or environment variables) and reference them in the respective deployment stages of the pipeline.

Using IAM roles for EC2 instances is the most secure and recommended method. The application running on the EC2 instance can automatically retrieve temporary credentials from the EC2 metadata service. The AWS SDKs are designed to automatically look for these credentials. This avoids the need to store any long-term credentials on the instance, simplifying credential management and enhancing security.

Amazon Kinesis Data Streams is designed for real-time processing of streaming data at scale. To maintain the order of events for each user session, the developer can use the user's session ID as the partition key. All events with the same partition key will be sent to the same shard, ensuring in-order processing within that shard.

AWS Lambda integrates natively with Kinesis Data Streams. It can be configured as a consumer to process records from the stream in micro-batches. Lambda scales automatically with the number of shards and the volume of data, making it ideal for handling traffic spikes without manual intervention.

Amazon API Gateway usage plans are the standard way to manage throttling and quotas for your APIs. A developer can create a usage plan, define the rate (requests per second) and burst limits, and then associate this plan with one or more API stages. If the API requires client-specific keys, the plan can be associated with API keys.