Overview of Container Technology
Kubernetes Overview:
- Kubernetes is an orchestration service that simplifies the deployment, management, and scaling of containerized applications.
- The smallest unit manageable in Kubernetes is a pod.
- A pod consists of one or more containers with its storage resources and IP address that represent a single application.
- Kubernetes also uses pods to orchestrate the containers inside it and to limit its resources as a single unit.
Features Of Kubernetes :
Service discovery and load balancing
Kubernetes enables inter-service communication by assigning a single DNS entry to each set of containers. This way, the requesting service only needs to know the target's DNS name, allowing the cluster to change the container's location and IP address, leaving the service unaffected. This permits load-balancing the request across the pool of containers providing the service. For example, Kubernetes can evenly split incoming requests to a MySQL service taking into account the availability of the pods.
Horizontal scaling:
Applications can scale up and down manually or automatically with a configuration set, with either the Kubernetes command-line interface or the web UI.
Self-healing:
Kubernetes can use user-defined health checks to monitor containers to restart and reschedule them in case of failure.
Automated rollout:
Kubernetes can gradually roll updates out to your application's containers while checking their status. If something goes wrong during the rollout, Kubernetes can roll back to the previous iteration of the deployment.
Secrets and configuration management:
You can manage the configuration settings and secrets of your applications without rebuilding containers. Application secrets can be user names, passwords, and service endpoints, or any configuration setting that must be kept private.
Operators:
Operators are packaged Kubernetes applications that also bring the knowledge of the application's life cycle into the Kubernetes cluster. Applications packaged as Operators use the Kubernetes API to update the cluster's state reacting to changes in the application state.
OpenShift Overview:
- Red Hat OpenShift Container Platform (RHOCP) is a set of modular components and services built on top of a Kubernetes container infrastructure.
- RHOCP adds the capabilities to provide a production PaaS platform such as remote management, multitenancy, increased security, monitoring and auditing, application life-cycle management, and self-service interfaces for developers.
- Beginning with Red Hat OpenShift v4, hosts in an OpenShift cluster all use Red Hat Enterprise Linux CoreOS as the underlying operating system.
OpenShift Features:
OpenShift adds the following features to a Kubernetes cluster:
Integrated developer workflow:
RHOCP integrates a built-in container registry, CI/CD pipelines, and S2I, a tool to build artifacts from source repositories to container images.Easily expose services to the outside world.
Include built-in and self-analyzing metrics service and aggregated logging.
OpenShift brings unified tools and a UI to manage all the different capabilities.
