Kubernetes does for container orchestration what Python and C have done for high-level programming languages. Just as those languages provide users with libraries and abstractions, so they are able to focus on the tasks in front of them without getting bogged down in the complexities of memory management, Kubernetes provides high-level abstractions for container management. This enables Kubernetes users to keep their focus on how they want the applications to run, rather than worrying about the specifics of how they will implement it.
Kubernetes is designed from the ground up to increase the agility of DevOps processes. When Kubernetes was first developed, the premise behind it was to take problems faced by developers in an agile environment and establish automation tools to help alleviate those problems significantly. The result is an environment that allows you to go from development to production in a more seamless way.
This makes Kubernetes ideal for those running a CI/CD pipeline. The tools available and the nature of Kubernetes itself establish a perfect—if perhaps complex—environment for continuous deployment. You have complete control over individual Pods while maintaining a centralized configuration of the environment, which means there are several important reasons why Kubernetes has become the top orchestration platform for organizations running DevOps and Agile best practices.
Centralized Configuration for Easy Deployment
Kubernetes is set up to be modular and decentralized, but the fact that the environment also uses a centralized system for managing configurations is actually its biggest strength. In a continuous implementation cycle, you can alter the individual Pods inside a service and transition from one Pod—with an older version of the application—to another in a seamless way.
Rather than shutting the whole system down, Kubernetes lets you change which Pods or groups of Pods to access when a request is made. The environment automatically recognizes the new configuration as soon as it is committed, and future requests are immediately directed to the identified Pods.
Zero downtime is also made possible thanks to the support of ConfigMap and Kubernetes Secrets. Rather than hard-coding server configurations directly to the apps, you can deploy Secrets containing the required API keys and credentials with every iteration of the software. This also minimizes the risk of misconfiguring a Pod and causing a catastrophic failure.
Flexible Pods and Containers
Pods are often seen as the smallest unit in a Kubernetes environment, but that is not necessarily true. You can run multiple containers in a single Pod for better resource usage. Pods simply act as the fundamental unit on top of which containers are running. Pods connect those containers to the server, provide pre-allocated storage, and allow access to the network.
The flexibility of Pods means you can run containers that provide additional features or services alongside the main app. It is also much easier to configure the Kubernetes environment to be more service-oriented. Resource utilization can be maximized and features such as load balancing and routing can be completely separated from microservices and app functionalities.
Better Communications Between Services
Microservices lend themselves to operating at optimal functionality in the Kubernetes environment. Both support modular development and they allow for large functions to be divided into smaller chunks of specific toolsets. More importantly, microservices can communicate with each other.
Kubernetes does not require services within the same namespace to be configured in a certain way to allow them to communicate. In fact, Kubernetes is designed to automatically figure out how requests are best routed to the intended services.
The design of Kubernetes and its implementation in a cloud environment means you can stop worrying about configuring how services are structured and connected. Rather than anxiously dealing with microservices management and discovery, more resources can be directed towards developing the services and features themselves.
Another core component that makes Kubernetes suited to the CI/CD cycle is its immense reliability. Kubernetes has a series of health-check features that eliminate many headaches associated with deploying a new iteration. In the past, we may have all seen times when a new Pod being deployed was often faulty and crashed frequently, but Kubernetes manages to keep the entire system running through its built-in auto-healing feature.
You can improve the reliability of a Kubernetes environment using the two main approaches for checking the health of applications. Kubernetes automatically checks for liveness and restarts an application if it is in an ‘unhealthy’ state. The process happens much faster than when carried out manually by an administrator to maintain reliability.
Kubernetes can also detect readiness automatically if we have configured in the health checks in the Pod specification that we want kubelet to run against a given Pod/s. When new Pods are deployed, Kubernetes waits until they are ready for traffic before disabling the old ones, even when the services have been changed. This prevents catastrophic failure and adds an extra safety net to protect the local-public migration routine.
Rolling Updates and Instant Rollbacks
Even the way new Pods are added to the Kubernetes environment suits the CI/CD workflow perfectly. In Kubernetes, you don’t replace a Pod. Instead, there is a rolling update feature which belongs to the Kube ‘deployment’ object (a deployment object contains one or more copies of the same Pod) which is responsible for updating the Pods in a way that does not cause impact to the end user. Then we tell the service to direct traffic to the new Pod.
The previous two health checks prevent one Pod from bringing the entire system down. At the same time, they provide sufficient warnings for you to notice that the new Pods are not working properly and update accordingly. Rolling back to a previous revision stored in version control is as easy as reverting to the older service configuration. This can also be done via kubectl quickly.
Kubernetes in a CI/CD workflow is a gem for those tackling DevOps. It allows the entire process, from version control to release, to be completed in rapid successions, all while maintaining scalability and reliability of the production environment. For more on Kubernetes, check out our Working with Microservices & Kubernetes article here.
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