Kubernetes vs. Docker – Which Should I use?
Using containers to manage applications has become an increasingly attractive choice for developers, but with so many options, it often begs the question: Kubernetes vs. Docker – which should I use?
When researching container management systems, it’s common to encounter the ‘Kubernetes vs. Docker’ debate. However, this comparison can be somewhat misleading!
In reality, Kubernetes and Docker aren’t direct competitors. The two platforms are built around different concepts to provide solutions to distinct problems.
Essentially, Docker is a containerization platform, while Kubernetes is a container orchestrator that manages container platforms like Docker. Since both focus on containerization, there is often confusion surrounding the platforms.
With that said, we aim to clear up any confusion between Kubernetes and Docker by explaining how each works and how they compare against each other.
Kubernetes vs. Docker: The Benefits of Using Containers
Both Kubernetes and Docker revolve around the idea of applications running in containers. Before delving into the specifics of each platform, it’s important to understand what containers are intended for and how you can benefit from using them.
Key Benefits of Containers:
- Reduced Overhead: Containers require fewer resources compared to traditional virtual machines (VMs) as they don’t need to include an operating system.
- Portability: Applications running within containers can be effortlessly deployed across various operating systems and hardware platforms.
- Isolation: The isolated nature of containers ensures smoother operations, as the failure of one application doesn’t affect others.
- Simplified Management: Operations like container creation, destruction, and replication are quick, speeding up the development process.
What is Docker?
Docker is an open-source platform that uses operating system virtualization to deploy software in lightweight, portable packages called containers. In addition to deploying these containers, Docker provides various tools to help develop, ship, and run applications within them.
Containers are lightweight because they don’t require hypervisors; instead, they run directly on the host machine’s kernel. While each container is isolated with its own software, libraries, and configuration files, they can still communicate with each other.
This architecture offers a fantastic platform for developers, with features that greatly simplify and streamline the entire application development process.
One of Docker’s standout features is its use of images, which are essentially save states of a container. This ensures that applications can run on any Linux machine, regardless of customized settings.
Images can be easily shared over the internet using Docker Hub, an online library where users can download community-created Docker images or upload their own.
How Docker Works
When discussing Docker, people usually refer to the Docker Engine, the client-server application that facilitates the creation and running of Docker containers.
Components of Docker Engine:
- Server (Daemon Process): The long-running program (dockerd) that manages Docker objects like containers, images, networks, and volumes.
- REST API: Specifies interfaces for communication with the daemon process.
- CLI Client: The command-line interface (docker command) uses the REST API to control the daemon process.
In practice, the CLI uses the REST API to control the daemon process through direct CLI commands or scripting.
The daemon process then creates and manages the relevant Docker objects, like containers, images, networks, and volumes.
What Docker Does Well
As mentioned earlier, Docker excels at providing a straightforward method of bundling all the packages and configurations needed to run a software application within a portable container.
This container and image system greatly simplifies the process of building complex software applications. Multiple Docker containers can be easily combined to create more complicated systems, eliminating the need to manually build these individual functions.
For example, a complex system might require a database server, application server, and web server to run side-by-side. Normally, you would need to configure each of these individually. With Docker, however, you can deploy pre-configured images of these applications, saving you lots of time and effort!
Additionally, you can separate the requirements and dependencies for each type of server into their respective containers. If your database server requires a different version of a certain library compared to your web server, Docker allows you to manage this easily.
The isolated nature of the container system also brings security benefits. Since each container is separated, any security compromises will only affect that container and not others, helping to stop malicious third parties in their tracks.
What Docker Doesn’t Do Well
Like all web technologies, there are a few downsides to using Docker.
Performance: Any virtualized environment comes with a performance penalty, and Docker is no exception. Running Docker containers side-by-side with an alternative hosted on a physical machine will usually show the containers performing slightly slower. However, this performance difference is often negligible for many applications.
If latency and speed are absolutely paramount for your application, then Docker might not be your best option. It really depends on what you’re developing!
Simultaneous Services: If your application requires two services to run on the same machine simultaneously, there may be better alternatives. Docker isn’t designed for this use case, and the container system might not accommodate it well.
What is Kubernetes?
Kubernetes is an open-source container orchestration system used for managing containerized systems and applications with a focus on automation. Originally developed by Google, it automates the deployment, scaling, and availability of applications or services running in containers.
In simpler terms, Kubernetes provides better ways of coordinating and running applications within containers across a cluster of machines.
As Kubernetes is used for managing containerized applications, it’s designed to work with various containerization tools, including Docker. This is one of the key reasons it shouldn’t be considered a direct alternative but rather a system that can be used in conjunction with Docker.
In a production environment, Kubernetes is an excellent choice due to its automated cluster management features. When used correctly, it ensures that all of your applications are online, secure, and running efficiently.
How Kubernetes Works
At a basic level, Kubernetes connects individual physical or virtual machines into a cluster, using a shared network to allow communication between machines. This cluster is where all Kubernetes components, workloads, and capabilities are configured.
To understand how Kubernetes works, you should first understand two important terms:
- Node: Refers to the virtual machines and/or bare-metal machines that Kubernetes manages.
- Pod: A unit of deployment in Kubernetes referring to a collection of containers (commonly Docker-based) that need to coexist together. For example, an application might rely on a web server and caching server containers, both encapsulated side-by-side in a single pod.
A simplified view of Kubernetes can be broken down into two core components:
- Master Node: This server acts as both the gateway and the brain of the cluster. The Master node is the primary point of contact with the cluster and is responsible for much of the centralized functions Kubernetes provides. It also handles communication between other components in the cluster and exposes an API to users and clients. All activities in the cluster are coordinated by the Master node.
- Working Nodes: These servers are responsible for running workloads using both local and external resources. Nodes receive work instructions from the master server, then create or destroy containers accordingly. The nodes also adjust network rules to route traffic to the appropriate destinations.
Each working node has a Kubelet, an agent that manages the node and communicates with the master node. The nodes are also usually equipped with tools for handling container operations, such as containerd and Docker.
Communication between the master node and working nodes is handled by the Kubernetes API. This API allows for querying and manipulation of objects within the Kubernetes architecture, like pods, namespaces, and events.
What Kubernetes Does Well
Perhaps the best situation to use Kubernetes is in a production environment. Due in part to its advanced automation features, Kubernetes can help streamline your day-to-day operations by handling much of the application management for you.
In addition to ensuring that all of your applications are up and running, Kubernetes can also be configured to self-heal. Essentially, this means that any unresponsive containers will automatically be replaced with new ones, mitigating any significant outages.
Scaling your application is also significantly easier with Kubernetes. Horizontal auto-scaling allows your cluster to adapt to any major increases in resource usage. For example, Kubernetes might automatically start new containers to handle CPU-intensive areas of your application when it’s under heavy load.
Kubernetes can also help simplify the deployment of your applications while minimizing downtime. For instance, when deploying a new version of your application, Kubernetes allows you to keep the existing version running while you deploy the new version. It will then ensure that the new version is working correctly before taking the old version offline.
Of course, these are just a few areas where Kubernetes excels—there are far too many to list here!
What Kubernetes Doesn’t Do Well
While Kubernetes can be hugely beneficial, it is not perfect by any means.
For many, Kubernetes can seem extremely complicated, which is often considered one of its biggest drawbacks.
As mentioned earlier, Kubernetes is very powerful and capable of a lot. However, to use it to its fullest, you need to be prepared to invest significant time in learning how it works, often through trial and error. This can prove frustrating for many when figuring out how to deploy an application.
Complexity with Kubernetes extends beyond the initial setup. Ongoing management requires using separate administrative tools like kubectl. Training your team to use such tools can reduce productivity as they adjust to the new development workflow.
Transitioning to Kubernetes from a different platform can also be cumbersome and time-consuming. Software needs to be adapted to work smoothly on the platform, and some processes might need modification to function properly in the new environment. The amount of work required varies depending on the application but can often be quite challenging.
Lastly, if your application isn’t very complex, intended for a large audience, or requires significant computing resources, Kubernetes might be overkill. If you’re just hosting a simple website or a basic application, Kubernetes might not be your best choice. It could cost more than necessary and won’t necessarily bring many benefits.
Now that we’ve given an overview of Kubernetes and Docker, how they work, and their pros and cons, you should have a better idea of which platform to use.
As we’ve explained, the two platforms aren’t direct competitors but are complementary to each other.
Kubernetes is very often used with Docker to great effect. Docker provides an excellent containerization system for your applications to run on, and Kubernetes offers efficient ways of managing these containers. So, depending on the application you’re developing, you may want to use both!
At UKHost4u, we offer a variety of plans perfect for launching a Docker deployment or managing a Kubernetes cluster. No matter what type of application you’re developing, our tools will help you streamline and improve every step of the development cycle. Explore our Docker Hosting Plans and Kubernetes Hosting Plans to find the best solution for your needs.
