Kubernetes vs Docker: What’s the difference?

What is the difference between Kubernetes and Docker?

Docker is a suite of software development tools for creating, sharing and running individual containers; Kubernetes is a system for operating containerized applications at scale.

Think of containers as standardized packaging for microservices with all the needed application code and dependencies inside. Creating these containers is the domain of Docker. A container can run anywhere, on a laptop, in the cloud, on local servers, and even on edge devices.

A modern application consists of many containers. Operating them in production is the job of Kubernetes. Since containers are easy to replicate, applications can auto-scale: expand or contract processing capacities to match user demands.

Docker and Kubernetes are mostly complementary technologies—Kubernetes and Docker. However, Docker also provides a system for operating containerized applications at scale, called Docker Swarm—Kubernetes vs Docker Swarm. Let’s unpack the ways Kubernetes and Docker complement each other and how they compete.

 

What is Docker?

Docker is a suite of tools for developers to build, share, run and orchestrate containerized apps.

How does Docker work?

In Docker’s client-server architecture, the client talks to the daemon, which is responsible for building, running, and distributing Docker containers. While the Docker client and daemon can run on the same system, users can also connect a Docker client to a remote Docker daemon.

Developer tools for building container images

Docker Build creates a container image, the blueprint for a container, including everything needed to run an application – the application code, binaries, scripts, dependencies, configuration, environment variables, and so on. Docker Compose is a tool for defining and running multi-container applications. These tools integrate tightly with code repositories (such as GitHub) and continuous integration and continuous delivery (CI/CD) pipeline tools (such as Jenkins).

Sharing images

Docker Hub is a registry service provided by Docker for finding and sharing container images with your team or the public. Docker Hub is similar in functionality to GitHub.

Running containers

Docker Engine is a container runtime that runs in almost any environment: Mac and Windows PCs, Linux, and Windows servers, the cloud, and on edge devices. Docker Engine is built on top containerd, the leading open source container runtime, a project of the Cloud Native Computing Foundation (CNCF).

Built-in container orchestration

Docker Swarm manages a cluster of Docker Engines (typically on different nodes) called a swarm. Here the overlap with Kubernetes begins.

 

What is Kubernetes?

Kubernetes is an open source container orchestration platform for managing, automating, and scaling containerized applications. Kubernetes is the de facto standard for container orchestration because of its greater flexibility and capacity to scale, although Docker Swarm is also an orchestration tool.

 

How does Kubernetes work?

A Kubernetes cluster is made up of nodes that run on containerized applications. Every cluster has at least one worker node. The worker node hosts the pods, while the control plane manages the worker nodes and pods in the cluster.

What is Kubernetes used for?

Organizations use Kubernetes to automate the deployment and management of containerized applications. Rather than individually managing each container in a cluster, a DevOps team can instead tell Kubernetes how to allocate the necessary resources in advance.

Where Kubernetes and the Docker suite intersect is at container orchestration. So when people talk about Kubernetes vs. Docker, what they really mean is Kubernetes vs. Docker Swarm.

Benefits of using Kubernetes and Docker

When used together, Kubernetes and Docker containers can provide several benefits for organizations that want to deploy and manage containerized applications at scale.

Some of the key benefits of using include:

• Scalability: Kubernetes can scale containerized applications up or down as needed, ensuring they always have the resources they need to perform optimally. This is helpful for applications that experience a boost in traffic or demand.
• High availability: Kubernetes can ensure that containerized applications are highly available by automatically restarting containers that fail or are terminated. This can keep applications running smoothly and prevent downtime.
• Portability: Docker containers are portable, meaning they can be easily moved from one environment to another. This makes it easy to deploy containerized applications across different infrastructures, such as on-premises servers, public cloud providers, or hybrid environments.
• Security: Kubernetes can secure containerized applications by providing role-based access control, network isolation, and container image scanning. This can help to protect applications from unauthorized access, malicious attacks, and data breaches.
• Ease of use: Kubernetes can automate the deployment, scaling, and management of containerized applications. This can save organizations time and resources, and it can also help to reduce the risk of human error.
• Reduce costs: By automating the deployment and management of containerized applications, Kubernetes and Docker can help organizations reduce IT operations costs.
• Improve agility: Kubernetes and Docker can help organizations to be more agile by making it easier to deploy new features and updates to applications.
• Increase innovation: Kubernetes and Docker can help organizations to innovate more quickly by providing a platform that is easy to use and scalable.

Use cases for Kubernetes and Docker

When used in tandem, Kubernetes and Docker create a dynamic duo that unlocks a myriad of possibilities for seamless and scalable application deployment.

Here are a few use cases for using Kubernetes and Docker together:

• Deploying and managing microservices applications: Microservices applications are made up of small, independent components that can be easily scaled and deployed. Each microservice can be containerized using Docker, and Kubernetes can manage the deployment and scaling of these services independently. This allows for better maintainability, scalability, and fault isolation.
• Dynamic scaling: Together, Kubernetes and Docker enable dynamic scaling of applications. Kubernetes can automatically adjust the number of application instances based on demand. When traffic spikes, new containers can be spun up to handle the load, and when the load decreases, excess containers can be scaled down. This elasticity ensures efficient resource utilization and cost savings.
• Running containerized applications on edge devices: Kubernetes can be used to run containerized applications on edge devices, ensuring that they’re always available and up to date. Docker has redefined how applications are packaged and isolated. Docker eliminates the “it works on my machine” dilemma by encapsulating an application and its dependencies within a standardized container. This consistency ensures the application runs the same way across development, testing, and production environments.
• Continuous integration and continuous delivery (CI/CD): The combination of Docker and Kubernetes streamlines CI/CD pipelines. Docker images can be integrated into the CI/CD process, ensuring consistent testing and deployment. Kubernetes automates the deployment process, reducing manual intervention and accelerating the time to market for new features.
• Cloud-native applications: Docker and Kubernetes are cloud-agnostic, making it easier to deploy applications across different cloud providers or hybrid environments. This flexibility allows organizations to choose the most suitable infrastructure while avoiding vendor lock-in.