Choosing Between Kubernetes and Docker: Insights for IT Leaders

In software development, containerisation technologies have become a popular way to create, deploy, and manage software applications.

These technologies provide a way to package and deploy software applications across different computing environments. They do so by packing everything needed to run an application—such as code, libraries, and configuration files—into lightweight containers that can be deployed on any infrastructure supporting the underlying operating system.

With containerisation solutions, companies can improve application scalability while reducing manual effort and operational complexity.

Kubernetes and Docker are two popular tools in the containerisation ecosystem. As they are distinctly different systems handling different roles, it's important for IT managers to understand how each tool works. Understanding this empowers them to choose the right solution for their specific needs.

Here, we will explore the key differences between Kubernetes and Docker, their pros and cons, and how they have been used in the real world. Finally, we will cap off with guidelines and recommendations to help IT management choose the best containerisation solutions for their projects.

The key difference between Kubernetes vs Docker

The major difference between these popular tools is that Docker is a containerisation platform while Kubernetes is a container orchestration platform.

A containerisation platform, such as Docker, allows you to create, run, and share containers that simplify the movement of software applications and services. It is very similar to virtual machines in isolating and running applications but differs in its approach and underlying architecture.

Kubernetes, on the other, is a container orchestration tool that works like a central command centre to automate the deployment and management of containers across a cluster of machines or servers.

What this means is that Kubernetes and Docker are not necessarily direct rivals. Rather, comparing Kubernetes vs Docker for software development is like comparing a hammer and a screwdriver for construction. Some construction jobs need a hammer, some projects require a screwdriver, and both may be necessary in other circumstances. 

The same applies to Kubernetes and Docker. So, the more important questions are: In what situations would you need Kubernetes, and when would Docker be the better choice? Are there any situations where you would need both? To answer these questions, we would first need to understand how each tool works and what it does.

Overview of Kubernetes and Docker and how they work

Since Docker is the tool that creates the container that Kubernetes deploys, let’s first dive into how Docker works, followed by an overview of Kubernetes.

Docker overview

There is a fascinating backstory to why Docker has its name, and it links back to the history of the shipping industry.

From as early as 1792, goods would be transported across seas and oceans in wooden crates, sacks, or kegs. Labourers at shipping ports, known as dockers, would pack each crate, sack, or keg onto a ship one at a time. When the ship reached its destination, dockers would unload each item and pack them back onto trucks or railway trains. 

The process entire was slow, repetitive, and inefficient. Then, a revolution happened in 1956 when Malcolm McLean, an American entrepreneur and transportation pioneer, invented the shipping containerisation system. 

McLean simplified the entire logistics process by inventing a standard type of shipping container that can be unloaded from a ship and straight onto a truck, and vice versa. Now, dockers only need to pack a container once, and then the container can be moved from any mode of transport to another until it reaches its final destination.

The containerisation platform, Docker, draws inspiration from this shipping industry revolution. By containerising elements of software applications into a container that can be moved from any development environment to another, DevOps engineers no longer need to engage in repetitive and mundane configuration tasks. 

Docker components

The most common components are the Docker engine, Dockerfile, and Docker Compose.

1. The Docker engine, or Docker runtime, is the core component to build and run Docker containers on a host system. It consists of a Docker Daemon, a Docker CLI, a container runtime, an image registry, and networking and storage capabilities.
2. Dockerfile is a simple text file with a list of commands, such as OS network specifications and file locations that the Docker Engine needs to build a Docker container image.
3. Docker Compose is an open standard tool to define and run multi-container applications with a single Docker build command via the Docker CLI. 

Kubernetes overview

Kubernetes, also known as K8s, is an open source system that automates deploying, scaling, and managing containerised applications. 

The peculiar name, Kubernetes, was carefully chosen from an ancient Greek word for ‘helmsman’. A helmsman is a person who steers a ship, which is why Kubernetes chose the ship wheel icon for its logo.

If Docker acts like the dockers that pack goods into shipping containers, then Kubernetes is the entire system of steering the movement of these containers. This would include tools such as cranes, forklifts, and conveyors, as well as systems and processes to manage operations and resources efficiently.

Kubernetes components

In the Kubernetes ecosystem, the tools and systems to manage moving containerised applications are termed as pods, nodes, and control planes. All these components combine to become a Kubernetes cluster.

Pods are the smallest components of a Kubernetes cluster and are made by grouping containerised applications into logical units that can be easily managed and discovered. A Kubernetes node, which consists of physical or virtual machines, can then host multiple pods. The orchestration layer of multiple nodes is then known as a control plane.

A Kubernetes cluster may include other components and resources, such as networking, storage, add-ons, and extensions.

Advantages and disadvantages of Kubernetes vs Docker

Now that we have an overview of how Kubernetes and Docker work, let's examine their pros and cons.

Docker

Advantages

• Modularity: Docker breaks down applications into smaller, independent services that can be assembled into separate containers. By taking on a modular approach to building containers, application development is simplified, and integration of third-party services becomes much easier.
• Portability: The containers that Docker puts together are lightweight and portable. As they are self-contained units of software, they can run consistently in an environment, eliminating compatibility issues.
• Efficiency: Docker containers are lightweight and share the host system’s OS kernel, which means they have lower overheads and faster startup times. This makes them much more efficient than traditional virtual machines.
• Isolation: Due to how Docker containers provide isolation at the application level, multiple Docker containers can run on a single machine without conflict. The result is a secure and predictable environment for running applications.
• Reproducibility: Once an application is packaged as a Docker container, the same container can be deployed consistently across different environments, from development to production.

Disadvantages

• Steep learning curve: While Docker's core functionalities are easy to grasp, users new to containerisation technologies will have an additional layer of complex Docker commands to learn.
• Complexity: Docker simplifies creating and deploying containers, which can easily lead to a proliferation of containers. Managing a large number of containers can get very complex without proper management and monitoring tools.
• Security: Docker runs on the host’s operating system, which means that any vulnerabilities or misconfigurations in the host can potentially affect all containers running on it.

Kubernetes

Advantages

• Container orchestration: When container sprawl and management get too complex for Docker, Kubernetes can be used in tandem with Docker. Kubernetes handles scheduling containers onto appropriate nodes, ensuring the right number of containers are running, and managing load balancing.
  
  
• Scalability: In addition to container orchestration, Kubernetes automatically scales resources as needed by adding or removing instances of containers based on workload demands. It then allocates the necessary resources to handle increased traffic or demand.
  
  
• High availability: With built-in mechanisms for high availability, Kubernetes can automatically recover or replace containers that fail. These mechanisms ensure applications remain accessible and reliable.
  
  
• Rolling Updates and Rollbacks: Kubernetes allows applications to update with zero downtime. Its rolling updates feature gradually replaces older versions of containers with new ones, ensuring an application remains available during the update process. Its rollback features enable going back to the previous working version quickly if any issues occur during an update.
  
  
• Extensibility and Ecosystem: The Kubernetes ecosystem provides a wealth of resources, community support, and integration possibilities. DevOps engineers can leverage additional tools, such as Helm for package management, Prometheus for monitoring, and Istio for service mesh capabilities, to enhance and extend the functionality of a Kubernetes cluster.

Disadvantages

• Steep learning curve: Similar to Dockers, Kubernetes poses a steep learning curve for those who have never used a container orchestration tool or distributed system before.
  
  
• Operational overhead: Running and maintaining a Kubernetes cluster requires operational resources. Smaller teams without a dedicated DevOps team may struggle to keep up with tasks such as clutter provisioning, monitoring, scaling, upgrading, and troubleshooting.
  
  
• Complexity of networking and service mesh: Networking in Kubernetes can be complex, especially when dealing with advanced network configurations, cross-cluster communication, or integrating with the existing networking infrastructure.

Use cases for Kubernetes and Docker

Kubernetes and Docker can benefit a wide range of projects, especially those that involve deploying and managing containerised applications. Here are some popular use cases.

Docker

Docker containers offer the flexibility to deploy a wide range of applications, such as:

• Micro-services-based apps
• Pre-deployment application testing
• Infrastructure as code
• Early application development
• Isolated app infrastructure
• Multi-environment standardisation
• Loosely coupled architecture
• Multi-tenancy
• Deploying OS-agnostic applications
• Speed up CI/CD pipeline deployments
• Disaster recovery
• Reduce IT infrastructure costs

Kubernetes

This “Kubernetes in the Wild Report 2023” provides insights into how organisations actually use Kubernetes in production. Some of the key insights of use cases from this report show that:

• Kubernetes is emerging as the “operating system” of the cloud.
  
  
• The strongest growth areas for Kubernetes are security, databases, and CI/CD technologies.
  
  
• Open source software, such as Prometheus, drives a vibrant Kubernetes ecosystem.

As an operating system for the cloud, Kubernetes has been used by several companies in a few ways.

• Google originally designed Kubernetes to scale its business arm that provides public-cloud infrastructure, such as Gmail, YouTube, Google Maps, and many others.
  
  
• Dynatrace uses Kubernetes for any new software project, from building pipelines to SaaS offerings.
  
  
• The New York Times used Kubernetes to move from print to the web to Cloud Native

Factors to consider when choosing a containerisation solution

Docker is a good choice for developers and DevOps teams who want a simple and efficient way to package and deploy applications. Kubernetes is a good choice for organisations managing and operating large and complex containerised applications. 

If you’re choosing between Kubernetes vs Docker, or perhaps wondering if you need a hybrid solution, then you’ll need to take into account the following factors:

1. Scale and complexity: Kubernetes is more suitable for larger, complex projects.
   
   
2. Orchestration and automation: If you need sophisticated orchestration capabilities, such as auto scale, then Kubernetes is the way to go.
   
   
3. Development environment: For local development and testing, Docker’s simplicity is the favoured choice amongst individual DevOps engineers and small teams.
   
   
4. Infrastructure flexibility: Kubernetes offers more flexibility and portability if you're looking to scale.
   
   
5. Team expertise and resources: Kubernetes has a steeper learning curve than Docker. You’ll need to ensure you have the resources to train or hire qualified DevOps engineers to make the most of these tools.

Recommendations for IT management

When adopting Kubernetes or Docker, we recommend connecting to the ecosystem and community support around each tool.

Kubernetes has a vibrant and extensive ecosystem with a large community of contributors, making finding resources, plugins, and support easier. Since Kubernetes is the seed technology used for the Cloud Native Computing Foundation (CNCF), connecting with the CNCF community can also be beneficial.

Docker also has a strong community that supports knowledge sharing, troubleshooting, collaboration and networking, community contributions, and access to skill-training events.

Furthermore, connecting with the communities surrounding each tool will also give IT management access to a vast network of expertise, best practices, trends, and industry insights.

Conclusion

In summary, Docker simplifies the creation and packaging of containers, while Kubernetes provides advanced orchestration features for managing and scaling these containers efficiently.

Depending on the specific needs of a project, they can be used independently or in tandem. Together, they enable developers to build and deploy applications consistently, optimise resource utilisation, and automate the management of containerised applications at scale.