In the previous blog we discussed Docker, a heaven-sent software development platform tool that makes it easy for us to develop and deploy applications inside neatly packaged virtual compartments called containers using different operating systems to smoothly and logically integrate them.
Kubernetes can be used with Docker as well as other container based platforms such as RunC and Cri-o. Although Kubernetes and Docker are the two most popular containerising tools on the market, they are closely related and can work together, which is great, but while we know that Docker is an amazing tool, as we discussed the ins and outs of Docker in our previous blog, what makes Kubernetes different and unique? What sets these two apart from each other? Let’s dive in!
What is Kubernetes?
To put it bluntly, Kubernetes is a container management system developed in the Google platform but can be used on any platform. It’s an orchestration tool used to manage and deploy many containers in different environments, be it physical, virtual or cloud. In other words, it’s a completely flexible container tool used to deliver the most complex applications consistently and is especially helpful when the quick deployment of applications is required. (It’s important to note that Kubernetes should be used in microservice architecture environments – a cloud native architecture where a single application is made up of many loosely coupled and independently deployed smaller components or services).
Let’s give you some context shall we:
Let’s say you’ve developed an application and you predict that there will be an increase in the number of users, so you need to start scaling your application; i.e. increasing the number of instances of your application, where an instance is just a replica of the application, in order to meet user demand – stressful and terrifying, we know.
It can be difficult to actively manage each instance to ensure that its being built, deployed and has an appropriate amount of computing resources, such as CPU and RAM to process its requests, without ensuring this, you’re asking for big problems in the long run.
Here is an example of where Kubernetes proves useful:
Kubernetes gives you access to the production environment and allows you to scale efficiently, it can also manage applications that are run on Docker containers, ensuring that each container is healthy. It allows you to stop, start, restart and monitor a large number of containers and is also able to perform load balancing and distribute network traffic between containers, while being able to actively remove and create new containers seamlessly, without any hassles, what a relief! Another amazing feature is that Kubernetes also has a Graphic User Interface (GUI) in the form of a dashboard, unlike Docker, this allows you to view stats of ongoing tasks in your Kubernetes, which is extremely useful to the user!
So how does it work exactly?
The Kubernetes engine manages a cluster of nodes consisting of at least one master node and several worker nodes. The master node is responsible for running important processes such as communicating with APIs and providing an entry point to the Kubernetes cluster, and it also keeps track of what’s happening within the worker nodes, for example, whether the containers in the worker nodes are healthy or require repair, whereas the worker nodes are responsible for running applications in containers., which is where Kubelets come in.
A Kubelet is a ‘node agent’ that allows a process to run on each worker node making it possible for clear communication in the cluster to occur and for tasks to be performed without any issues at hand. Each node contains Docker containers with different applications running on it, for example two completely different platforms – WordPress and MySQL. A different number of Docker containers can be running on each node depending on the workload distribution. Within a worker node there are pods, these pods are the smallest unit inside of a Kubernetes cluster that a user can interact with and they consist of one or more Docker containers; however, it is best practice and safest to ensure that only one application is allocated per pod. The only time there is more than one container in a pod is when you have a main application that needs help from other containers to perform its required functions – between the master node and worker nodes, there is a virtual network which is responsible for turning all of the nodes into one powerful machine!
What are the advantages you ask?
- High Availability
This ensures that there is no single point of failure in a Kubernetes cluster. This can be done by using more than one master node. If only one master node is used in a Kubernetes cluster and it fails, pods cannot be created or restarted when necessary, however, if there is more than one master node and one of them fails, another master node can take over ensuring that the orchestration of containers is not disrupted. Best practice would be an odd number of master and worker nodes, with 3 being the minimum number for each.
Kubernetes allows you to easily increase or decrease the number of replications of your application, each replication is in a container that is then sitting safely in a Kubernetes pod.
- Health Checks
Kubernetes monitors containers and quickly replaces them if they are in an unhealthy state, such as being unable to process requests.
Kubernetes is truly a massive breakthrough for developers as it allows teams to keep up with the requirements and demands of modern software development. In the absence of Kubernetes, developers would often be forced to script their own software deployment, scaling and update workflows which in turn forces some organisations to employ large teams to handle those tasks. Kubernetes allows us to obtain maximum utility from containers and build cloud-native applications that can run literally anywhere, completely independent of cloud-specific requirements. This is clearly an extremely efficient model and a game changer for application development and operations we’ve been so eagerly waiting for!
Contact us today to discuss taking your company’s capabilities to the next level by employing Kubernetes to assist you, we can’t wait to accompany you along this exciting journey!