To troubleshoot issues in OCI, the option that is not valid is: Trace performance issues in the Application Performance Monitoring service by enabling Function traces. While the Application Performance Monitoring service in OCI allows you to monitor and trace the performance of your applications, it is specifically designed for monitoring OCI Functions (serverless functions) and does not directly apply to all types of applications. The other options mentioned, such as configuring logs in the OCI Logging service, leveraging OCI Cloud Guard for debug logs, viewing service metrics in the OCI Monitoring service, and using OCI Service Connector Hub for log forwarding, are valid options for troubleshooting and monitoring applications in OCI.

A pod is the smallest and simplest unit in the Kubernetes object model that you create or deploy2. A pod represents a single instance of a running process in your cluster. Pods contain one or more containers, such as Docker containers. When you create a pod, you define how much CPU and memory (RAM) each container needs.A pod can also include storage volumes, IP addresses, options that govern how the container(s) should run, and more2.Pods are the basic building blocks of larger Kubernetes constructs such as deployments, replica sets, and services2.

The term that describes a group formed by a master machine and a worker machine in a Kubernetes architecture is 'Cluster'. A cluster in Kubernetes consists of one or more master machines and multiple worker machines (also known as nodes). The master machine manages the overall control plane and orchestrates the deployment and management of containers on the worker nodes. The worker nodes are responsible for running the containers and executing the workloads. The cluster is the fundamental unit of organization and management in Kubernetes, providing the infrastructure and resources to run and manage containerized applications. It ensures high availability, scalability, and fault tolerance for the applications deployed within it.

The two characteristics of microservices are: Microservices can be independently deployed: One of the key principles of microservices architecture is the ability to independently deploy each microservice. This means that changes or updates to one microservice can be made and deployed without affecting other microservices. It allows for faster and more frequent deployments, enabling agile development and scalability. Microservices communicate over lightweight APIs: Microservices communicate with each other through lightweight APIs (Application Programming Interfaces). This enables loose coupling between microservices, as they can interact with each other using standard protocols like HTTP/REST or messaging systems like RabbitMQ or Kafka. Lightweight APIs facilitate flexibility and interoperability between microservices, making it easier to develop and maintain complex systems. The remaining statement, 'All microservices share a data store,' is not a characteristic of microservices. Microservices are designed to be autonomous and have their own data storage or database. Each microservice has its own data store, which promotes the principle of bounded contexts and avoids tight coupling between services. This allows for better scalability and independence of data management within each microservice.

The correct answer is: 'Edit the tenancy global retention policy.' To ensure that container images never get deleted from the Oracle Cloud Infrastructure Registry (OCIR), you should edit the tenancy global retention policy. The tenancy global retention policy is a setting that determines the retention behavior for all the images in the OCIR across the entire tenancy. By editing this policy, you can define the retention behavior that suits your requirements. To edit the tenancy global retention policy, you would typically perform the following steps: Access the Oracle Cloud Infrastructure Console and navigate to the OCIR service. Go to the 'Policies' section or 'Settings' section in the OCIR service. Locate the tenancy global retention policy settings. Modify the retention policy to specify the desired retention behavior. In this case, you would set the policy to retain all images, ensuring they are never deleted from the repository. By setting the global policy of image retention to 'Retain All Images,' you can ensure that the container images in your OCIR repository are permanently retained and not subject to deletion based on any default or automatic retention rules. The other options mentioned are not directly related to ensuring that container images are never deleted from the repository: Creating a group and assigning a policy to perform lifecycle operations on images or writing a policy to limit access to the specific repository in your compartment are access control measures and do not address the retention of images. Setting the global policy of image retention to 'Retain All Images' is the correct action to achieve the desired outcome of preventing image deletion from the repository.