Kubernetes and Docker might look like similar technologies from a distance. This could be probably because both these technologies help you run applications with Linux containers. However, if you analyze both the technologies in depth, you will soon find that both Kubernetes and Docker work at different layers of the stack.
It is essential to understand the concept of both Kubernetes and Docker to be able to build a modern cloud infrastructure. In this article, we will have a closer look at both these technologies and understand the basic differences between them.
Put simply, Kubernetes is an open source platform that is used for automating the Linux container operations. It works by eliminating a range of manual processes which are otherwise required in order to deploy and scale the containerized applications easily.
This way you can make a cluster of a group of hosts running Linux containers, and Kubernetes would come to your rescue by helping you in managing the clusters easily.
Talking about the history of Kubernetes, they were originally designed and developed by the Google engineers. It is important to mention here that the credits for developing Linux container technology also go to Google. Further, Google has revealed this a lot of time that they make a widespread use of containers. Let’s not forget that it is the same technology Google’s cloud services are based on.
That’s not it. It would not be wrong to say that a large part of Google runs on Kubernetes and this is why Google makes more than 2 billion container deployments per week, through its internal platform called Borg.
Borg is the predecessor to Kubernetes and so the shortcomings of Borg were well-taken care by Kubernetes.
So, now, let’s understand how Kubernetes actually work?
The architecture of Kubernetes employs various abstractions and concepts. Some of these concepts are native to Kubernetes, while others make use of already existing notions.
The highest-level concept of Kubernetes, the cluster, is nothing but a group of apps running Kubernetes. Every Kubernetes cluster has a master, the system that controls and commands the other Kubernetes machines present in the cluster.
A Kubernetes cluster which is available readily repeats the master’s facilities across various cluster machines. However, the controller manager and job scheduler are managed by just one master at a time.
Digging the Kubernetes cluster further, you will find that each cluster has Kubernetes nodes which could be physical machines. These nodes are then responsible for running pods which is the most basic object in a Kubernetes cluster.
Each pod can consist of one or more than one containers and represents the running process or the single instance of an application.
Needless to say, apps reside in multiple containers which must be deployed across a range of server hosts. This is when Kubernetes comes to your rescue and provides the required management capabilities to you to make the Kubernetes deployment of containers at various scales simple and straightforward.
Kubernetes orchestration helps in building application services that make use of multiple containers. These containers are then scheduled across a cluster and scaled. Kubernetes then keeps an eye on the containers and manages their health for a longer period of time.
Not only this, you can also integrate Kubernetes with other services like storage, networking, security and the like in order to build a robust container infrastructure.
However, the robustness of the containers ultimately depends on the use of Kubernetes. Generally, Linux treats containers as fast and efficient virtual machines. Kubernetes is necessary because once you start scaling your application, you would need multiple containers that would work together as the individual services. As the application scales further, the complexity grows with the growth of the number of containers. Thus, you need a system which can manage all the containers, and this is when Kubernetes come to your rescue.
Kubernetes helps you in a range of ways. From helping in organizing the containers together in a ‘pod’ to helping in balancing the load, it makes the entire management of the containers simpler.
Thus, to sum up, it can be said that Kubernetes helps you in:
This was all about Kubernetes, Next, let’s explore deep about Docker and how is it different from Kubernetes.
Now that we have understood which a Kubernetes is, it is the right time to understand the concept of Docker.
Explained simply, Docker is a tool which helps you in creating, deploying and running various applications using containers. Once developed and deployed, the container would help you in packaging the application with all that it would need to run successfully, like libraries and other dependencies.
Thus, this way containers ensure that the application if transported from one Linux machine to the other would still work as intended irrespective of the customized settings that the recipient machine could have.
To sum up, it can be said that Docker is kind of a virtual machine which helps the applications to run on the same Linux kernel as they were previously running on and only need the other requisites which are not already present on the host computer. This benefits in two ways – it boosts the performance of the system, which also reduces the size of the application.
What’s more? Docker is open source, and thus can be used by anyone!
Docker consists of a client-server architecture and performs all the actions of containers using Docker server.
Docker client provides the commands to the server through a REST API. The client could be on a completely different host, or on the same host as the server.
Docker consists of images, which are also called as its basic building blocks. These images combine together to form containers and can be configured with applications or used as a stand-alone template. The images are organized in a layered approach. Thus, a new image is added as a layer on the top of the previous one.
All these images are stored in a Docker registry which helps you in sharing and building images with your team. Additionally, you can keep the registry as public or private. What this means is that if your registry is public, all the images stores in it can be easily accesses by other users. However, you can also create a private registry wherein you can keep all the images private.
Docker is an effective tool that benefits both the system administrators and developers alike. It is this quality of Docker that makes it an ideal choice for DevOps i.e., developers and operations.
Docker provides a relief to the developers as they only need to focus on the development of tool, without worrying about the machine it will finally run on. On the same lines, Docker is of great help for Operations team as well as it Docker reduces the number of systems the application must be tested on, thus reducing the overall expenses.
It is important to mention here that Dockers are gaining wide popularity. As per an estimate, 66% of the companies who try it also end up adopting it. This is perhaps by the companies adopting Docker have gone up by 30% when compared to the last year.
This is all owing to a range of benefits that Dockers have an offer, some of them being:
This pretty much explains what a Docker is. However, it is worth mentioning here that Docker is a platform whereas Kubernetes is an orchestration tool. Thus, by comparing Kubernetes with Docker, you are not trying to compare apples with oranges, which is not a fair comparison at all.
Docker Swarm is the orchestration tool from Docker and comparing Docker Swarm with Kubernetes sounds logical. Before we jump to the actual Docker Swarm vs Kubernetes differences, let’s understand what Docker Swarm is.
Docker recently introduced its own container’s orchestration called as Docker Swarm. The orchestration makes use of its own standard networking and API. This makes it easier for you to use it in an environment where Docker containers are already been used.
Precisely, Docker Swarm has four key working principles:
As discussed above, both Kubernetes and Docker Swarm are orchestration tools. While Kubernetes is fairly popular and is been used by Google for years, Docker Swarm is still at its infant stage and was released in June 2016. Let’s have a look at how these two platforms differ:
When compared to Kubernetes, Docker Swarm is far easier to use. This is perhaps because it has a pretty simple learning curve. Kubernetes is often termed as difficult and complex by various developers because they find it hard to configure.
On the other hand, Docker Swarm is very simple and can be easily used by novices and expert programmers alike.
When working with Kubernetes, you need to deploy it by using a pods combination and other micro-services.
On the other hand, you can deploy the Docker Swarm applications with the help of micro-services and services in a Swarm cluster.
As far as scaling or auto-scaling is concerned, Kubernetes gets the brownie points here. Although both Docker Swarm and Kubernetes are scalable and can run around 30,000 containers on one nodes, Kubernetes goes a step further and offer auto-scaling which is not offered by Docker.
Docker Swarm is undoubtedly easy to use on the one hand, but this also translates to the fact that the platform allows you to play very little with it. You can definitely realize pretty simple stuff, but when it comes to exploring new realms and trying something new, this is one aspect when Docker Swarm doesn’t perform better.
While on the other hand, Kubernetes can be configured in a more customized manner. Although it is a bit difficult to learn, it provides you a range of opportunities to try and experiment.
Docker Swarm connects the containers that are running on its cluster nodes quite easily. If more networks need to be connected, that could be done manually. Further, Docker Swarm secures all the connections made between nodes with the use of TLS authentication certificates.
On the other hand, Kubernetes makes use of flannel to achieve container networking. It joins the containers in a virtual network. Like Docker Swarm, TLS authentication can be achieved but certificates require to be generated and installed manually at all nodes!
Docker Swarm communicates with the scheduler and ask it to use a new image while updating the container. This way, the update is rolled out in stages which prevents a complete outage of the service. This also makes way for easy rollback if it doesn’t go as planned.
On the other hand, Kubernetes adopts a progressive update approach wherein one pod is updated at a time which prevents complete service outage at times.
Thus, both Kubernetes and Docker Swarm handle updates as per their architecture with the main goal of preventing a complete service outage.
Kubernetes takes the cake here as well as it comes equipped with a robust logging and an in-built monitoring solution which helps you in keeping a close eye on your container deployments.
Talking about Docker, yes, you can monitor the deployments as well, however, only with the help of third party applications. Although, this is not a limitation, but yes, this definitely makes the monitoring a bit difficult which is not the case with Kubernetes.
According to the discussion we have had above, it is clear that Kubernetes is better than Docker Swarm. This also pretty much explains why Docker team recently backed down and released their own enterprise tool to enable easy integration with Kubernetes.
So which one should you choose between Kubernetes and Docker is entirely your choice. If you need an advanced tool, Kubernetes would be the right choice. However, if you are working with container clusters and so not need any specific configurations, then Docker Swarm could be a good choice as well.
Also, it is worth mentioning here that Kubernetes has an appreciably larger community of developers in spite of the fact that it involves a steep learning curve with a hard installation process. On the other hand, Docker Swarm is still in its growing stage.
Further, the large community of Kubernetes also translates to better support, feature, and tools which is not the case with Docker. But, then again, if you are still learning the container services, Docker Swarms could be a great place to start off.
So, what are your views on this? Who do you think is a clear winner? Do let us know in the comments below!