Docker vs Kubernetes: What's the Difference?

In addition to serving different needs, Docker and Kubernetes are often used in tandem rather than as substitutions to one another. Docker contains software to build, package, and run applications in a container, and Kubernetes contains software to manage a cluster of containerized applications. A development team can use Docker to build an application, and Kubernetes to run, expand, connect, and manage the application.

In simple terms, Docker allows developers to package an application in a container, and Kubernetes allows developers to expand, connect, monitor, and manage applications in a production environment.

Container and deployment architecture have significant implications for the scalability, reliability, build speed, and-cost-efficiency of infrastructure for businesses creating SaaS products, APIs, eCommerce applications, or any other cloud-native services. Xcentric Services aids companies in assessing the needs and requirements of their application and developing the necessary tools for packaging their application as well as connecting containers and managing services in a production environment.

Comparison of Docker and Kubernetes: An Overview

Thinking of Docker and Kubernetes as alternatives competing for market share is a common beginner's mistake. Essentially, Docker focuses on the developer experience and the contained units of work. Kubernetes focuses on clustered workloads at scale.

Architecting a distributed application and determining the DevOps infrastructure required to support your application is where Docker vs Kubernetes differentiation becomes critical.

For most of Xcentric Services' clients, the question is not 'Docker or Kubernetes?', but 'How do we combine containerization and orchestration with cloud services and automation?' based on the requirements of an application.

Docker vs Kubernetes: Containers vs. Orchestration

When many containers are spread out among lots of machines, orchestration is necessary for managing the workloads. There may be a need to set where the workloads have to run, re-run crashed workloads, control the flow of traffic, manage service discovery, adjust the number of replicas, and set the desired state.

Kubernetes covers all those things. Kubernetes is not the first and only option out there for orchestration solutions, but this tutorial will cover Kubernetes for a couple of reasons. First, the open-source nature of Kubernetes means that it is possible to learn and set up Kubernetes for free. Second, Kubernetes has useful onboarding documentation that can quickly introduce newcomers to the software. Third, this software currently has a massive ecosystem that is constantly growing around it.

It is also necessary to discuss how to build, test, deploy, and run applications using Docker and Kubernetes from the perspective of a newcomer in order to understand the relationship between some key concepts.

Kubernetes primarily coordinates containers. Kubernetes orchestration is typically used alongside Docker, which packages an application and its dependencies for distribution as a portable and standalone container. Kubernetes works by automating how containerized applications are managed across the cluster. A cluster is a group of machines that are managed by Kubernetes together.

Kubernetes and Docker can live together in application architecture. This consistency is one of the many reasons Docker helped redefine modern software development.

What is Docker?

Docker is a platform and various tools that can be used for the purpose of development, packaging and implementation of applications in containers.

One of the most important components of Docker is Docker Engine. Docker Engine has a daemon, APIs, as well as a command-line interface through which developers can create Docker objects like containers, volumes, networks, and images.

A typical workflow in the development process looks like this:

• A developer writes code.

• A Dockerfile is written, which describes how to package said code

• Docker builds the image

• The image is checked on a local machine

• The image is uploaded to a registry

• Finally, the image is deployed

Tooling in Docker extends beyond starting a single container. For instance, Docker Compose is a tool to develop or test multi-container applications. Docker Compose scaffolding is done using a YAML Compose file. It is useful for development and testing, for running CI workflows, and for easier multi-container environments.

Documentation for Docker

While some may argue that “Docker is just containerization,” Docker offers more tooling and abstractions for development and broader management of containers, built over container technology.

For a company developing a new SaaS product, an API, an e-Commerce platform, or a custom web app, Docker can help provide more consistent development and deployment environments

What is Kubernetes?

Kubernetes is an open-source tool for automation of deployment, operations, and scaling of containerized applications. It is designed to handle distributed systems of applications, rather than simply managing a container on a developer's machine.

Kubernetes adds concepts of Pods, workloads, networking, scheduling, and many others. Consider an application that contains the following components:

• Frontend

• API

• Worker process

• Database

• Caching service

Running these independently on a single development computer is not very hard. Running these components reliably on many production servers is more complex. Kubernetes helps with that.

This is what makes Kubernetes a valuable additive to application infrastructures. Complexities within Kubernetes mean it’s not the right choice for all web applications and API’s or for those from smaller businesses.

Kubernetes needs to be architecturally appropriate given the application’s requirements. This is the case even for applications that are not as popular.

How Docker and Kubernetes Work Together

It’s important to understand that Docker and Kubernetes work at different phases of an application’s lifecycle. Typically, a workflow may look like:

Application Code > Docker > Container Registry > Kubernetes >Production Workloads

A development team creates an application image. This gets stored in a registry and becomes accessible for Kubernetes to create workloads for the application.

To illustrate this with an example, let's say there's a company with some proprietary Python API. Here is how we can package the API and its dependencies into an image such as:

Company-api:v1.4 (add image here)

This image, of course, can be pushed to a container registry.

Kubernetes has the ability to deploy the desired number of workloads. Kubernetes schedule, service discovery, health management and other cluster-related controls are taken care of. It's worth mentioning that Kubernetes is quite capable of making workload orchestrations without the presence of Docker Engine.

Often in a build or development workflow, Docker is used, and in production orchestration, Kubernetes is used. It is critical to understand the roles and responsibilities of Docker and Kubernetes in pipeline development. From the perspective of a build system, Docker is used to create and test container images, and from a deployment system perspective, Kubernetes is used to manage workloads.

For cloud migration, containerization and orchestration may, in effect, become a part of an organization’s modernization strategy. The right architecture of the desired system depends on application size, traffic patterns, deployment frequency, team expertise, availability requirements, and cloud environment. In such a scenario, an experienced partner is crucial.

Xcentric Services is able to assess a client’s existing application architecture and help make the appropriate moves towards containerization, design the necessary deployment architecture, and determine whether Kubernetes is appropriate for the deployment or if a simpler deployment with Docker would work.

Does Kubernetes Use Docker?

No, Kubernetes doesn’t use Docker as its built-in container runtime, post version 1.24. That said, Docker-built container images are completely compatible with Kubernetes. This is one of the most misunderstood aspects of the Docker vs Kubernetes discussion.

Kubernetes used to support Docker Engine with dockershim. Kubernetes announced the deprecation of dockershim in December 2020. dockershim was removed from Kubernetes v1.24.

Kubernetes now interacts with compatible container runtimes through the Container Runtime Interface (CRI). Documentation for Kubernetes shows how to run Docker Engine through an additional cri-dockerd adapter with containerd and CRI-O. Kubernetes removed dockershim and support for Docker Engine because dockershim was deprecated in 2020 and was removed in Kubernetes v1.24.Kubernetes requires a CRI-compatible runtime and has documentation for containerd and CRI-O. Docker-built images are able to run in Kubernetes.

The distinction can be summarized as follows:

Kubernetes has stated that Docker-produced images are able to run in a CRI-compliant runtime because they adhere to the OCI image specification.

So, Does Kubernetes Need Docker?

Kubernetes does not need to use Docker Engine as the container runtime. Teams are able to use Docker during development and image building, whereas Kubernetes runs these images with the selected runtime on the cluster.

What's Next With Docker Swarm?

Unlike Docker itself, Docker Swarm is more of a legitimate Kubernetes alternative, as it is Docker's own orchestration technology. Docker and Kubernetes address different primary problems. Swarm and Kubernetes have similarities with regard to orchestration.

When it comes to orchestration, Kubernetes is flexible, whereas Swarm is designed for simplicity. Operating Kubernetes can be easier.

Consideration Docker Swarm Kubernetes

Simplest setup | Easier learning curve | Simpler Docker integration | Smaller ecosystem

More involved setup | Steeper learning curve | Container-runtime agnostic | Distributed, broader ecosystem

Lower operational complexity | Strong for complex production environments

Kubernetes allows more flexibility in a complex environment. Docker Swarm is fit for a simple, small project.

Docker Swarm vs. Kubernetes is an orchestrator vs orchestrators question and needs more exploration.

This depends on your goals and what problems you’re trying to solve.

Deploy an isolated application packaged for consistency? Use Docker.

Distribute to multiple machines with automated scaling, service discovery, and self-healing? Use Kubernetes.

Using Kubernetes because an application runs on Kubernetes is a mistake. Kubernetes provides several benefits, but those benefits include configuration, monitoring, networking, security, deployment, and operations.

A Kubernetes cluster is most likely unnecessary to support a small marketing website with low traffic. A multi-service SaaS platform with independently deployable APIs, workers, automated scaling, high availability, and multiple production environments, however, is a strong argument for using Kubernetes.

This is an area where engaging a development agency like Xcentric Services can be helpful. Rather than making a one-size-fits-all technology decision, an experienced team will analyze your application's workload, deployment requirements, growth, cloud infrastructure and maintenance. Based on their analysis, they will suggest the right decision from the list of available Docker, Kubernetes, managed services, or simpler architectures.

Docker vs Kubernetes: Which One Does Your Business Need?

Knowing when your business needs Docker or Kubernetes means understanding the architecture of your business. More often than not, Docker is a better choice than Kubernetes. Docker can help streamline development by creating consistency between developer machines, testing environments, and deployment pipelines.

Kubernetes only makes sense when the operational challenges surrounding the runtime of containers are addressed. Consider the following when evaluating available architectures:

Pricing is also a factor. Kubernetes deployment also involves container management, cluster management, observability, networking, storage, CI/CD, backups, and updates within a production environment. For some, these features are crucial. For others, these features add unwanted complexity.

At Xcentric Services, we try to match application needs with infrastructure. Selling Kubernetes will not be a successful sale even if it is a technically advanced approach. Your project might require containerization, cloud deployment, backend engineering, DevOps automation, or scalable architecture. The technology stack should be in accordance with the business necessity.

Why Architecture Planning Matters for Docker and Kubernetes Projects?

Your development team should evaluate the service boundaries, expected traffic, deployments, availability, data architecture, team skills balance, security, and your cloud strategy before deploying Kubernetes. The same applies for Docker.

These two systems together are only a portion of the infrastructure needing consideration. For example, Xcentric Services can help a growing SaaS company determine whether a containerized architecture should be kept simple or should implement cluster-based orchestration. For a company migrating an application to the cloud, the team can also decide which parts of the application should be containerized and which should be managed cloud services.

This approach can help developers avoid a pitfall: implementing an over-engineered solution before the business supports such complexity.

Build the Right Container Architecture With Xcentric Services

Figuring out the differences between Docker and Kubernetes is just the tip of the iceberg. The best architecture fit for your application is needed today and will accommodate the growth of your application tomorrow.

A small application may prefer to use Docker without Kubernetes, while a complex SaaS platform may use Docker with Kubernetes. Another application may be better off using a managed container platform, which eliminates the need for your team to administer all aspects of Kubernetes, including orchestration.

Xcentric Services can aid businesses in making the correct application development and infrastructure decisions. As a digital and design agency with software development capabilities, we can assist with the development of custom web applications and back end systems and with the development of APIs, cloud migrations, and containerization deployments, while also implementing deployment automation and scalable application architecture.

When thinking about Docker or Kubernetes, it’s not a choice of which to pick, least of all without considering the application requirements. Rather, the strategy is to adopt the simplest approach that will reliably satisfy the requirements.

Do you need help to decide if your application requires Docker, Kubernetes, or a more simple approach to deployment architecture? Xcentric Services can currently appraise your application as-is and provide a proposed development and deployment strategy that considers your goals, scale, and budget.