Kubernetes vs. Docker
Build, deliver, and scale apps faster with container technologies that work better together.
The Kubernetes vs. Docker question
The conversation around Kubernetes vs. Docker is often framed as either-or: should I use Kubernetes or Docker? This is like comparing apples to apple pie, and it’s a common misconception that you must choose one or the other.
The difference between Kubernetes and Docker is more easily understood when framed as a “both-and” question. The fact is, you don’t have to choose—Kubernetes and Docker are fundamentally different technologies that work well together for building, delivering, and scaling containerized apps.
Docker and the rise of containerization
Docker is open-source technology—and a container file format—for automating the deployment of applications as portable, self-sufficient containers that can run in the cloud or on-premises. Docker, Inc., although it shares a similar name, is one of the companies that cultivates the open-source Docker technology to run on Linux and Windows in collaboration with cloud providers like Microsoft.
While the idea of isolating environments is not new and there are other types of containerization software, Docker has grown to be the default container format in recent years. Docker features the Docker Engine, which is a runtime environment. It allows you to build and run containers on any development machine; then store or share container images through a container registry like Docker Hub or Azure Container Registry.
As applications grow to span multiple containers deployed across multiple servers, operating them becomes more complex. While Docker provides an open standard for packaging and distributing containerized apps, the potential complexities can add up fast. How do you coordinate and schedule many containers? How do all the different containers in your app talk to each other? How do you scale many container instances? This is where Kubernetes can help.
Kubernetes and container orchestration
Kubernetes is open-source orchestration software that provides an API to control how and where those containers will run. It allows you to run your Docker containers and workloads and helps you to tackle some of the operating complexities when moving to scale multiple containers, deployed across multiple servers.
Kubernetes lets you orchestrate a cluster of virtual machines and schedule containers to run on those virtual machines based on their available compute resources and the resource requirements of each container. Containers are grouped into pods, the basic operational unit for Kubernetes. These containers and pods can be scaled to your desired state and you’re able to manage their lifecycle to keep your apps up and running.
What’s the difference between Kubernetes and Docker?
While it’s common to compare Kubernetes with Docker, a more apt comparison is Kubernetes vs. Docker Swarm. Docker Swarm is Docker’s orchestration technology that focuses on clustering for Docker containers—tightly integrated into the Docker ecosystem and using its own API.
A fundamental difference between Kubernetes and Docker is that Kubernetes is meant to run across a cluster while Docker runs on a single node. Kubernetes is more extensive than Docker Swarm and is meant to coordinate clusters of nodes at scale in production in an efficient manner. Kubernetes pods—scheduling units that can contain one or more containers in the Kubernetes ecosystem—are distributed among nodes to provide high availability.
Kubernetes and Docker—better together
While the promise of containers is to code once and run anywhere, Kubernetes provides the potential to orchestrate and manage all your container resources from a single control plane. It helps with networking, load-balancing, security, and scaling across all Kubernetes nodes which runs your containers. Kubernetes also has built-in isolation mechanism like namespaces which allows you to group container resources by access permission, staging environments and more. These constructs make it easier for IT to provide developers with self-service resource access and developers to collaborate on even the most complex microservices architecture without mocking up the entire application in their development environment. Combining DevOps practices with containers and Kubernetes further enables a baseline of microservices architecture that promotes fast delivery and scalable orchestration of cloud-native applications.
In short, use Kubernetes with Docker to:
- Make your infrastructure more robust and your app more highly available. Your app will remain online, even if some of the nodes go offline.
- Make your application more scalable. If your app starts to get a lot more load and you need to scale out to be able to provide a better user experience, it’s simple to spin up more containers or add more nodes to your Kubernetes cluster.
Kubernetes and Docker work together. Docker provides an open standard for packaging and distributing containerized applications. Using Docker, you can build and run containers, and store and share container images. One can easily run a Docker build on a Kubernetes cluster, but Kubernetes itself is not a complete solution. To optimize Kubernetes in production, implement additional tools and services to manage security, governance, identity, and access along with continuous integration/continuous deployment (CI/CD) workflows and other DevOps practices.
Kubernetes and Docker solution architectures in production
Use AKS to streamline horizontal scaling, self-healing, load balancing, and secret management.
- 1 Use an IDE, such as Visual Studio, to commit changes to GitHub.
- 2 GitHub triggers a new build on Azure DevOps
- 3 Azure DevOps packages microservices as containers and pushes them to the Azure Container Registry
- 4 Containers are deployed to AKS cluster
- 5 Azure Active Directory is used to secure access to the resources
- 6 Users access services via apps and websites
- 7 Administrators access the apps via a separate admin portal
- 8 Microservices use databases to store and retrieve information
DevOps and Kubernetes are better together. Implementing secure DevOps together with Kubernetes on Azure, you can achieve the balance between speed and security and deliver code faster at scale. Put guardrails around the development processes using CI/CD with dynamic policy controls, and accelerate feedback loop with constant monitoring. Use Azure Pipelines to deliver fast while ensuring enforcement of critical policies with Azure Policy. Azure provides you real-time observability for your build and release pipelines, and the ability to apply compliance audit and reconfigurations.
- 1 Rapidly iterate, test, and debug different parts of an application together in the same Kubernetes cluster
- 2 Code is merged into a GitHub repository, after which automated builds and tests are run by Azure Pipelines
- 3 The container image is registered in Azure Container Registry
- 4 Kubernetes clusters are provisioned using tools like Terraform; Helm charts, installed by Terraform, define the desired state of app resources and configurations
- 5 Operators enforce policies to govern deployments to the AKS cluster
- 6 The release pipeline automatically executes a pre-defined deployment strategy with each code change
- 7 Policy enforcement and auditing is added to CI/CD pipeline using Azure Policy
- 8 App telemetry, container health monitoring, and real-time log analytics are obtained using Azure Monitor
- 9 Insights are used to address issues and fed into next sprint plans
Build on the strength of Kubernetes with Azure
Deploying and managing your containerized applications is easy with Azure Kubernetes Service (AKS). AKS offers serverless Kubernetes, an integrated CI/CD experience, and enterprise-grade security and governance. Unite your development and operations teams on a single platform to rapidly build, deliver, and scale applications with confidence.