The cluster option that is the best fit for ensuring reliable operations of Kubernetes at scale while minimizing the operational overhead of managing the worker node infrastructure is using OCI OKE virtual nodes to eliminate worker node infrastructure management. OKE is a fully managed service that allows you to run and manage your Kubernetes cluster on OCI. A Kubernetes cluster consists of a control plane and a set of worker nodes that run your containerized applications. OKE provides a highly available and secure control plane that is managed by Oracle, while you are responsible for managing the worker node infrastructure. However, OKE also supports virtual nodes, which are serverless compute resources that are automatically provisioned and scaled by OCI based on your application workload demands. Virtual nodes eliminate the need for managing worker node infrastructure, such as security patches, updates, scaling, etc. Virtual nodes also offer a serverless Kubernetes experience, where you can focus on developing and deploying your applications without worrying about the underlying infrastructure. Verified Reference: [Container Engine for Kubernetes - Oracle Cloud Infrastructure Developer Tools], [Virtual Nodes - Oracle Cloud Infrastructure Container Engine for Kubernetes]

The OCI service that can help automate the provisioning of a new environment is OCI Resource Manager. OCI Resource Manager is a service provided by Oracle Cloud Infrastructure that enables you to automate the process of provisioning, updating, and managing infrastructure resources. It allows you to define your infrastructure as code using tools like Terraform, and then use Resource Manager to create and manage stacks. Stacks are the deployment units that contain the infrastructure resources defined in your code. By leveraging OCI Resource Manager, you can automate the provisioning of a new production environment by defining the required infrastructure resources in a stack using Terraform code. Resource Manager will then handle the creation and management of these resources, ensuring that your environment is provisioned consistently and according to the de-fined infrastructure as code. Therefore, OCI Resource Manager is the recommended service to automate the provisioning of a new environment in Oracle Cloud Infrastructure.

The two valid log categories with regard to the logging service in Oracle Cloud Infrastructure (OCI) are: Audit logs: Audit logs capture actions and events related to resource operations in OCI. These logs provide visibility into who performed an action, what action was performed, and when it occurred, helping with compliance and security monitoring. Custom logs: Custom logs allow users to define and send their application-specific log data to OCI logging service. Users can create custom log groups and log streams to organize and manage their log data. This enables centralized log management and analysis for custom applications and services running in OCI. Query logs and User logs are not valid log categories in OCI's logging service.

In the Deployment Pipeline, when a deployment stage fails during the deployment of an update to production, the recommended action is to: Rollback the failed stage in the pipeline to the previous successful released version. By rolling back the failed stage to the previous successful version, you can revert the deployment to a known stable state and prevent the failed changes from being re-leased to production. This helps to maintain the stability and integrity of the application. It allows you to address the issues encountered in the failed stage, make necessary fixes or adjustments, and then proceed with the deployment again once the issues are resolved. The other options mentioned are not the most appropriate actions to perform in this scenario: Automating backup and using the rerelease stage: While backups are important for data protection, automating backup and using a rerelease stage would not directly address the failure in the deployment stage. It is more focused on data backup and recovery. Adding Rescue and Trigger stages: Adding Rescue and Trigger stages might help in certain situations, but they are not the primary solution for handling a failed deployment stage. They are more related to error recovery mechanisms or additional deployment steps, rather than specifically addressing the failed stage. Using OCI DevOps Trigger and Rerun tool: While OCI DevOps Trigger and Rerun tool can be useful for automating and managing deployments, it is not specifically designed to handle a failed deployment stage. It is more focused on triggering and rerunning pipelines or stages based on specific conditions or events.

The three actions that the DevOps Engineer must perform to easily manage and troubleshoot applications on Oracle Cloud Infrastructure Container Engine for Kubernetes (OKE) are: Create a service account and the clusterrolebinding, obtain an authentication token for the service account using the kubectl command, and run a kubectl proxy command to enable the Kubernetes dashboard. This allows for easy access to the dashboard and management of deployed applications. Automatically deploy the Kubernetes dashboard during cluster creation, create the cluster using the API, and set the iskubernetesDashboardEnabled attribute to true. This ensures that the Kubernetes dashboard is automatically deployed and accessible. Manually deploy the Kubernetes dashboard on an existing cluster and access it using the appropriate URL. This involves deploying the dashboard manually and accessing it through the specified URL, which allows for management and troubleshooting of applications. Using these actions, the DevOps Engineer can effectively manage and troubleshoot applications deployed on OKE, leveraging the Kubernetes dashboard for enhanced visibility and control.