Kubernetes Vs. Docker Vs. OpenShift: What’s The Difference?

Containers are a big deal today. Because containers are software units that contain all the code, runtime, and dependencies required to run a distributed application, they help engineers test and run apps on any device and platform without compatibility issues.

Organizations can use containers to reduce engineering costs, speed up deployments, develop and test AI models, and automate more processes.

You probably want those benefits as well.

To help you choose the right container platform, we’ll compare the three in several areas, including configurability, ease of use, scalability, and security.

Kubernetes Vs. Docker Vs. OpenShift: Overview

There is often confusion surrounding Kubernetes, Docker, and OpenShift, despite 90% of organizations using containers in production.

As an example, Kubernetes is sometimes referred to as an all-in-one containerization platform. As this guide will reveal later on, that’s not true.

Also, you might be reading this after learning Kubernetes no longer supports Docker in kubelets. So perhaps you are wondering which platform to use moving forward.

OpenShift also markets itself as a Platform-as-a-Service (PaaS). Yet, OpenShift comprises Kubernetes components and works with Docker. Is OpenShift still reliant on Docker and Kubernetes?

Here’s a little background to get us started.

What Is Kubernetes?

Kubernetes (K8s) is an open-source container orchestration platform. Engineers use it to deploy and manage clusters of hosts running Linux containers. Kubernetes works on public, private, and hybrid clouds, as well as on-premises.

In 2015, Google donated Kubernetes to the Cloud Native Computing Foundation after designing, developing, and using it as BORG for almost a decade. RedHat, Amazon Web Services (AWS), and other vendors now contribute to the project.

A few key features of Kubernetes include:

What are the advantages of Kubernetes?

K8s has several benefits for container management, including:

As an engineer, you can also use Kubernetes as a platform, as a type of container operating system, or as a container orchestration tool. Despite this, Kubernetes is not a stand-alone container management solution since it requires different plugins and services to function.

What Is Docker?

Docker is an open platform for packaging and running applications in containers. The platform provides an end-to-end solution for building, shipping, testing, deploying, and maintaining containerized applications.

Docker launched in 2003, over a decade before Kubernetes became generally available. Several key components make up Docker:

What are the advantages of Docker?

Docker has the following benefits:

With Docker, you can develop and run distributed app architectures, run your code with standardized CI/CD pipelines, design highly scalable data processing systems, and set up fully managed platforms for your engineers.

What Is OpenShift?

OpenShift is a self-service containerization platform that Red Hat built for enterprise use. The platform enables engineers to build, deploy, and maintain container-based applications.

As part of Red Hat’s open project, OpenShift OKD, OpenShift leverages features from both Kubernetes and Docker, out-of-the-box enterprise security, and other efficiencies to deliver a powerful alternative.

Here’s an illustration of OpenShift as a Kubernetes distribution, for example.

Red Hat Openshift provides a consistent, cloud-like experience across:

What are the advantages of OpenShift?

Here are reasons to use OpenShift for container management:

As with Kubernetes and Docker, OpenShift can serve as a Platform (PaaS) and a tool (CaaS). It also supports automatic and manual scaling of containers, CI/CD, and multi-tenant deployments.

There’s more to it. OpenShift also provides premium support, a user-friendly login portal, and supports multiple programming languages (Go, Node.js, Java, Ruby, Python, and PHP).

In the next section, we’ll compare Kubernetes vs Docker.

Kubernetes Vs. Docker: What Are The Differences?

The biggest difference between Kubernetes and Docker is that while K8s is a container orchestration platform, Docker aims to be a complete containerization system. For example, Docker is a container engine (runtime) with a container orchestration tool (Docker Swarm or Swarm Mode), and a dedicated image registry (Docker Hub).

Here’s a quick overview of the differences:

Let’s dig deeper into the details.

1. Project or product

Docker comes in two versions: the Community Edition (CE) is an open-source project, and the Enterprise Edition (EE) is a paid product with enterprise-level support. For teams that want to focus on their code instead of configuring an open-source platform, Docker EE will be ideal.

The Kubernetes project is open-source and free. However, it requires investment in its infrastructure, including plugins and support services.

With Kubernetes and Docker CE, you need to download, install, set up, and oversee everything yourself, which requires skill and time. Yet, in either case, there is a large support and networking community to help you out.

2. Configuration and deployment

Kubernetes and Docker work with any Linux distribution. Some examples include Ubuntu, Fedora, and Debian. CentOS supports Docker as well. Deployment options include public, private, on-premises, and hybrid cloud setups for both. Also, both work on Macs and Windows desktops. Besides Windows 10, Docker is also compatible with Windows Server 1709 and 2016.

Moreover, if you need help managing Kubernetes, you can turn to managed services like Google Kubernetes Engine (GKE), Microsoft Azure Kubernetes Service (AKS), and Amazon Elastic Kubernetes Service ( Amazon EKS).

3. Ease of use

In Docker, you execute commands and automation through a single API using a client-server architecture.

A Dockerfile describes how an app is packaged into an immutable container image, after which the Docker server runs the appropriate commands to build the image. You can then run that image on various platforms, including Docker Swarm, Kubernetes, Mesos, and HashiCorp Nomad.

In Kubernetes, kubectl, a powerful API and command-line tool, automates the bulk of container management tasks.

Kubernetes coordinates the resources allocated to it on your behalf. Kubernetes controllers ensure applications and containers run as specified. This frees your engineers to focus on writing and improving code — not the infrastructure beneath it.

4. Container image management

Kubernetes is yet to include a native container image management system. For instance, no integrated image registry is available. But you can create a Docker image registry instead, such as Docker Hub. Kubernetes will pull images from there.

Docker includes the Docker Hub registry, where you can store and share images with compatible registries such as Azure Container Registry. Docker Pro or Team members also have access to the new Advanced Image Management Dashboard.

5. Scalability and size

Docker Swarm does not provide automated scaling based on resource utilization, unlike Kubernetes. You need to configure scaling manually with a command.

Kubernetes’ inherent extensibility and horizontal scaling capabilities make it the most scalable compared to Docker. For example, Kubernetes can support up to 5,000 nodes vs Docker Swarm’s 1,000 nodes and 30,000 containers (30 containers per node) instead of 300,000 containers on Kubernetes.

6. Security

Both Docker Swarm and Kubernetes support Role-Based Access Control (RBAC). However, Docker Swarm nodes also implement TLS mutual encryption and authentication to protect what they communicate with each other.

In Kubernetes, you need to configure your authentication safeguards. Thus, you would need to create bearer tokens or another method of authentication manually, which is time-consuming and tedious.

7. Updates

Kubernetes delivers about four releases per year. Kubernetes will notify you when new versions are available. It will also invoke the kubeadm upgrade command as soon as you decide to upgrade, simplifying the upgrade process.

However, Docker has a more frequent update schedule. It may be because it provides many tools, including Docker Engine, Hub, Compose, and Docker for Windows and Mac.

Quick reminder: if you plan to upgrade your existing installation, always create a backup first. In case an update does not work as expected, you can always roll back to the stable, earlier version.

8. Networking

Kubernetes does not have a native networking solution. Meanwhile, Docker uses multi-host networking, so you can choose an overlay network for your services. During initialization or updates, the Swarm Manager automatically assigns addresses to the containers in the network.

However, while Docker runs on a single node, Kubernetes runs across a cluster. Thus, Kubernetes nodes can more easily communicate with each other than Docker nodes.

9. Templates

Docker Hub offers pre-built images. You can also create new Docker apps using a library of templates with Docker Template, a CLI plugin that offers a top-level template command. Templates come in two forms; service templates (container images containing metadata and code) and application templates (a group of one or more service templates).

In Kubernetes, PodTemplates describes how to create pods. They are included in workload resources such as Deployments, DaemonSets, and Jobs. For each workload resource, the controller uses the PodTemplate within the workload object to create actual pods. This PodTemplate belongs to whatever workload resource your app runs on.

10. Continuous Integration and Continuous Delivery (CI/CD)

Kubernetes and Docker do not provide comprehensive CI/CD tools out of the box. Yet Docker and K8s enable developers to automate their CI/CD pipelines, adding features such as load balancing and storage orchestration.

Both support various third-party tools, such as CircleCI and Jenkins, to create robust CI/CD pipelines in Kubernetes or Docker.

Kubernetes Vs. OpenShift: What Are The Differences?

Red Hat designed OpenShift as an enterprise-grade, open-source container orchestration platform. To meet that grade, OpenShift packs additional security, productivity, and hybrid cloud features. Besides built-in monitoring and enterprise-level security, the platform also offers a self-service provisioning interface.

Here’s how Red Hat OpenShift compares with K8s.

Note that OpenShift Container Platform is Kubernetes-based, thus compatible with not only K8s but also most third-party tools that work with Kubernetes and other certified Kubernetes distributions.

OpenShift Vs. Docker: What Are The Differences?

Depending on your deployment, environment, or workload, Kubernetes may sometimes feel overkill. In that case, Docker and OpenShift are great alternatives to Kubernetes.

Here’s how Docker and OpenShift compare side-by-side.

Also note while Red Hat OpenShift Container Platform is based on Kubernetes, it is compatible with Docker tools, like Registry, Builder, and Docker Hub.

So, which container platform should you choose?

When To Use Docker

In small- to medium-sized deployments (and large-scale deployments when deployed with Kubernetes), Docker makes lightweight container images easy to build, deploy, and manage.

It includes a rich image registry, compatibility with most environments and tools, as well as support for building robust CI/CD pipelines if you are looking for a less complex container platform (than K8s).

When you build and run your own infrastructure, Docker Swarm also needs less setup and configuration than OpenShift or Kubernetes.

Yet it’ll help you build, ship, deploy, and maintain your containerized applications (using declarative YAML files), scale services to your desired state automatically, balance load between containers in a cluster, and safeguard access control for your services.

When To Use Kubernetes

Despite its steep learning curve and configuration, Kubernetes provides superior horizontal scaling (both automatic and manual) and supports a vast collection of plugins to extend its functionality.

With its self-healing capabilities and liveness/readiness probes, K8s helps you keep your system’s health close to your desired state at all times.

Since Kubernetes is open source, it’s also compatible with most platforms and tools. In addition, it includes a large and active developer community that provides technical support and networking opportunities.

Kubernetes’ autoscaling and 5,000-node support make it suitable for large-scale deployments, multiple deployment strategies, and greater isolation.

When To Use OpenShift

By default, OpenShift provides superior security features, hybrid/multi-cloud capabilities, dedicated customer support, and an easy-to-use web console for login. There are also free and paid editions available. Free OpenShift is open-source, making it flexible and extensible.

Moreover, it seamlessly integrates both Docker and Kubernetes, making it not only one of the best alternatives to Docker or K8s, but also the least likely to lead to vendor lock-in.

However, you may need to use Red Hat’s RHEL, Atomic Host, CentOS or Fedora to access native-level functionality.

How To Understand, Control, And Optimize Your Container Costs

No matter how you use containerized architecture, whether you use OpenShift, Kubernetes, or Docker, collecting, analyzing, and interpreting container cost data can be challenging. All three platforms support monitoring, but most cost tools only provide total and average costs, not more actionable details such as cost per customer, per feature, or per environment.

The result is that it can be tough to determine who, what, and why your container costs are changing to optimize them.

CloudZero can help.

CloudZero customers, such as Remitly and MalwareBytes, are already saving 6-10 hours weekly on managing costs. In addition, Drift is on track to save $4 million in AWS costs. You can, too. 

to see how CloudZero simplifies your Kubernetes cost management.

Frequently Asked Questions About Docker, Kubernetes, and OpenShift

Can I use Docker without Kubernetes?

Yes. Kubernetes is an open-source platform for managing containerized applications at scale. It works with different container runtimes, including containerd, CRI-O, and RunC. Still, K8s will deploy, scale, network, and manage your Docker containers at a large scale if you choose.

Can I use Docker without Kubernetes?

Yes. Docker builds, deploys, and runs container images without Kubernetes. The Docker Hub lets you store, search for, and retrieve the images. Docker Compose helps package containers into a multi-container app while Docker Swarm manages and optimizes resource utilization for containers.

Does OpenShift support Docker images?

Yes. Despite OpenShift’s Kubernetes-based architecture, you can seamlessly work with Docker images.

What runtime does OpenShift currently use?

The Red Hat OpenShift Container Platform currently uses Container Runtime Interface – Open Container Initiative (CRI-O) as its runtime.

Can I use Kubernetes and Docker together?

Yes. Experienced engineers often prefer Docker for development and Kubernetes for the operations phases of their deployments.

Author: Cody Slingerland

Cody Slingerland, a FinOps certified practitioner, is an avid content creator with over 10 years of experience creating content for SaaS and technology companies. Cody collaborates with internal team members and subject matter experts to create expert-written content on the CloudZero blog.