In recent years, containers have emerged as the preferred medium for deploying and managing applications in an abstracted distributed system. According to Gartner, over 75% of global enterprises will run containerized applications in production by 2022. As a result, worldwide container management revenue is also expected to grow from $465.8 million in 2020 to $944 million in 2024.
Containers are lightweight, portable software packages that make it easier for companies to scale and deploy applications quickly. However, while containers result in greater agility, faster delivery, and improved efficiency, it’s challenging to keep track of hundreds or thousands of them operating simultaneously in an enterprise. Hence the need for a container orchestration solution that can manage these complexities at scale.
Kubernetes, also called K8s, is an open-source container orchestration system that automates the management and deployment of containers in a distributed environment. Manual deployment is burdensome and error-prone. By automating the deployment process, productivity improves, wait time reduces and businesses release products much faster.
Originally designed by Google, today, Kubernetes is managed by the Cloud Native Computing Foundation (CNCF)—a software foundation that aims to make cloud-native computing accessible to everyone through its open-source projects. Thanks to the inputs received by a rich community of developers, Kubernetes has evolved into a powerful tool for container orchestration.
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What Makes Kubernetes Special?
Kubernetes successfully solves many of the issues associated with application deployment methods. Here is what makes Kubernetes special.
- Kubernetes is declarative in nature, which means you can declare the desired state of your applications and let Kubernetes match the actual state with the desired state.
- Kubernetes is a self-healing system. It continuously monitors your system to ensure it remains immune to failures.
- Kubernetes can auto-scale applications to adapt to additional workloads.
- Kubernetes streamlines and simplifies the deployment process.
“Kubernetes has gone beyond just an orchestration service and into today’s cloud-native operating system,” says Dotan Horovits, product evangelist at Logz.io. “In our organization, Kubernetes enables us to run mission-critical workloads of our SaaS application virtually. One of the advantages of using Kubernetes is that it makes it easy to operate uniformly in a multi-cloud environment and manage a multi-tenant setup.”
How Kubernetes Works
Kubernetes has a master-slave architecture system where the master node controls the worker nodes.
Master nodes manage the API endpoints and control all that goes on inside the cluster. You can communicate with the master node via the CLI or API. The master node has four components:
- Kube API server is the front end of the control plane and does all administrative tasks.
- Kube Scheduler selects the nodes to run the pods.
- Etcd Storage is a key-value store that stores critical information.
- Kube Controller maintains the desired state.
Worker nodes run applications on instructions of the master node. The components of worker nodes are:
- Kubelet is the primary node agent that runs on each worker node.
- Kube-proxy is a network proxy that runs on each worker node.
- Container runtime is a software program that manages container images.
The other important components of Kubernetes are:
- Pods are a collection of containers and are the smallest deployable object in Kubernetes. They are described in a Pod manifest that describes an object’s desired state.
- A cluster is a collection of nodes that run containerized applications inside Pods. Every cluster needs to have at least one node.
- Deployment automatically manages your pods and ensures that the required number of replicas are always running. Once you define the desired state, the Deployment Controller helps maintain it in that state.
- Persistent Volumes. Containers are by nature ephemeral. To ensure that data lives beyond the container’s lifecycle, Kubernetes uses persistent volumes—a kind of volume whose lifecycle is independent of any individual pod.
- Service is a communication channel that provides network access to Pods.
Also read: Containers are Shaping IoT Development
Advantage of Kubernetes
Standardization. As Sławek Górawski, blockchain developer at ULAM LABS notes, “One of the biggest pros of Kubernetes is standardization—using it across most of our projects allows us to configure them in a similar, predictable way. Someone familiar with K8s in one project can hop into another, run a few commands and get a decent overview of what is where in a matter of seconds. Everything is where you know it should be, whether you’re looking for deployments, routing, or TLS certificates.”
Flexibility. Kubernetes is highly flexible and can be deployed on multiple environments and infrastructures. Thus, Kubernetes can be deployed on an on-premise, private, or public cloud. In addition, Kubernetes can accommodate clusters ranging in size from a single node to as much as 5000 nodes.
Zero Downtime. Kubernetes subscribes to the rolling updates strategy, a method where your application is never down when performing updates. In this strategy, newer version pods incrementally replace older pods, thus ensuring you have zero downtime. In case there is a problem, the deployment is stopped without bringing down the entire cluster.
Rapid Scaling. Dynamic scaling is one of Kubernetes key features. This is possible in a declarative configuration setup where all you have to do is specify the number in the config file and declare the desired state. After that, Kubernetes takes care of the rest.
In fact, Kubernetes has three auto-scaling features: Horizontal Pod Autoscaler (HPA), Vertical Pod Autoscaler (VPA), and Cluster Autoscaler. While HPA increases and decreases Pods in response to changing workloads, VPA adjusts the memory resources and CPU for optimal use. Cluster Autoscaler, on the other hand, adjusts the size of a Kubernetes cluster by adding or removing nodes.
Disadvantages of Kubernetes
While there is no doubt that Kubernetes offers a ton of features, there are some pitfalls when it comes to adopting Kubernetes.
“The downsides of Kubernetes lie in its initial deployment. Kubernetes takes time to deploy in any system, and its flexibility means that learning it from zero is challenging,” David Johnson, Chief Technology Officer Mulytic Labs says. “If a company is obtaining cloud orchestration for the first time, and will use the in-house team for deployment, there will be an uphill battle. It is not advisable to start Kubernetes deployment with people fully new to cloud orchestration. Furthermore, Kubernetes can be overkill for small companies if the flexibility that Kubernetes has is not important.”
Organizations are also wrestling with several challenges when implementing Kubernetes.
- Lack of visibility and monitoring of resources within the cluster
- Avoiding misconfiguration exposures
- Ensuring the software supply chain inspects and reports upon container, configuration, and application security prior to any deployment
- Runtime security – implementation of a zero-trust model
“Enterprises migrating to Kubernetes find that existing firewalls and security measures aren’t sufficient for their new containerized environments,” observes Glen Kosaka, head of product security, SUSE. “In addition, Kubernetes and other container orchestrators and tools also present vulnerable (and increasingly targeted) attack surfaces themselves. Defending against these threats requires thorough security measures across the full application lifecycle. This means starting from the very beginning of development, through testing, and into deployment where applications are most vulnerable.”
Making Kubernetes Essential
Despite the steep learning curve involved, adopting Kubernetes is well worth it. Containers have become a staple need of modern enterprises, and only an adequate knowledge of Kubernetes will enable you to effectively manage every aspect of the application lifecycle.
“If I had to offer one bit of advice to any organization starting on their Kubernetes journey, it would be not to get stuck in endless analysis, one of the great things about Kubernetes is that it is infinitely reconfigurable, so start with something small and build upon it,” advises Mitchell Smith, Lead DevOps Engineer at Relevance AI. “Getting your first application to production on Kubernetes is the biggest challenge; it gets significantly easier from that point forward.”