Certified Kubernetes Application Developer (CKAD) Practice Test

What is the main role of a sidecar container in a multi-container pod?

1. It manages the networking requirements for the primary container

2. It assists the main container with a cross concern

3. It serves as a dedicated logging service

4. It acts as a load balancer for incoming requests

The correct answer is: It assists the main container with a cross concern

The primary function of a sidecar container in a multi-container pod is to assist the main container with cross-cutting concerns. This includes tasks that are vital for the application but not directly related to its primary business logic. Examples of these responsibilities can include service discovery, configuration management, monitoring, logging, authentication, and networking enhancements. By implementing these functionalities in a sidecar container, you can keep the main container focused on its core duties, thus adhering to the separation of concerns principle. While a sidecar may provide logging capabilities, it's not exclusively a logging service, as it may also handle other services which wouldn't appropriately fit the definition of a dedicated logging service. Similarly, while it could include networking tasks, it isn't primarily just for managing networking requirements and isn’t limited to acting as a load balancer for incoming requests. The versatility of sidecars in supporting many cross-cutting functions reinforces their role in enhancing and complementing the main application container.