Containerisation is an increasingly important element of the software development process. More organisations are moving to containerisation, with 61 per cent of IT executives saying it improves software quality and 72 per cent saying it enhances security. Organisations that are planning to transition to containerisation need access to suitable containerisation platforms. There are several powerful containerisation platforms out there to choose from, but the two most popular are Kubernetes and Docker.
This article will explore the advantages, disadvantages and main differences between the two popular tools, which both utilise containerd, a crucial piece of industry-standard container runtime software that makes Kubernetes and Docker containers possible.
Why Use Containers, Anyway?
Before we jump into exploring Kubernetes and Docker, it’s essential to understand what containers are and why they are used. Containers are a central component in the development, deployment and management of software applications. They are lightweight, portable and isolated virtual environments that package applications and their dependencies, ensuring consistent behaviour across numerous platforms.
Containers provide various benefits. For example, they help to ensure that applications run consistently across different environments, including development, testing and production. Containers also streamline and simplify the development and deployment processes, which allows teams to deliver new software products and features faster. But the benefits of containers do not stop there—they also enable developers and operations teams to work together efficiently in a standardised environment to better build, test and run applications.
Kubernetes: Open-Source Product-Grade Container Orchestration
Kubernetes is a powerful open-source platform designed to automate the deployment, scaling and management of containerised applications across machine clusters. It manages, schedules and deploys containers within its servers, called a Kubernetes cluster. By taking on many of the building blocks that are manually configured in Docker, Kubernetes simplifies the app deployment process and schedules containers amongst its cluster.
Additionally, Kubernetes can manage and route data between containers without administrators having to set it up themselves through Kubernetes Service, and it can gather and display metrics and information of different apps and containers. Because they both use containerd, Kubernetes can be used in conjunction with Docker.
The open-source platform continues to grow in popularity, with one survey finding that 70 per cent of a group of 1,296 IT leaders use Kubernetes. As with any platform, Kubernetes has its pros and cons:
Pros
Scalability: Kubernetes makes the management of large-scale deployments more efficient with features such as auto-scaling, rolling updates and load balancing.
Flexibility: Kubernetes is flexible because it supports a wide selection of deployment scenarios, container runtimes and networking configurations.
Self-healing: Kubernetes detects and replaces unhealthy containers, reducing service disruption.
High availability: The platform automatically distributes container workloads across nodes, ensuring high availability and fault tolerance.
Community support: Kubernetes has a large and active community, cited as one of the biggest reasons for the open-source platform’s meteoric rise.
Networking: It can manage network requests between different containers with container Load Balancing
Cons
Complex: Kubernetes has a steep learning curve and is challenging to set up, configure and manage for those who have not encountered the platform before. The complex nature of the platform may mean smaller engineering teams may struggle to use it effectively.
Time-consuming: The transition to Kubernetes takes a considerable amount of time, work and resources.
Docker: Efficient and Predictable Development
Docker is designed to help developers build, share and run applications. Similar to Kubernetes, Docker packages software into containers that contain everything the software needs to run, such as libraries, system tools, code and runtime. The platform takes away repetitive, mundane configuration tasks and facilitates fast, easy and portable application development for desktop and cloud.
It’s important to note that Docker is not only the name of the company but also encompasses the range of products it offers. For example, Docker Engine is a command-line tool to create and run containers, while Docker Desktop offers a GUI version that includes Docker Compose and Docker Swarm. Docker Compose is an extension that allows for multi-container applications, while Docker Swarm is an extension that can scale the number of pods up and down on different servers, making it more comparable to Kubernetes. Let’s explore the pros and cons of Docker:
Pros
Consistent environments: Docker ensures applications run consistently across development, testing and production environments, reducing the likelihood of issues and simplifying the development lifecycle.
Portable: Docker containers are portable, running on various platforms, including Windows, Linux and MacOS.
Lightweight: Docker containers have lower resource consumption compared to traditional virtualisation methods.
Easy to use: Docker is relatively easy to use compared to other containerisation platforms, with straightforward commands and an intuitive syntax for building, running and managing containers.
Version control: Dockerfiles (a file detailing how to build Docker images) and Docker images can be version-controlled, making tracking changes, rolling back to earlier versions and collaborating with team members easier.
Cons
Security: Containers are lightweight but at the cost of security. Since containers usually use a common operating system, there is a risk that various containers will be compromised if host systems are attacked.
Limited scalability: Docker offers limited scalability compared to Kubernetes.
Storage: There is no seamless way to connect Docker containers to storage.
Monitoring: Docker has no way of viewing the health of containers besides showing if a container is running or stopped
Kubernetes and Docker: The Main Differences
Now that we’ve explored the pros and cons of the two popular containerisation platforms, let’s discuss their main differences:
Scope: While Docker focuses on building and running containers, it is largely confined to single host/server once it expands to multiple servers managing this becomes difficult. Kubernetes provides a complete orchestration solution for managing containerised applications at scale.
Complexity: Docker has a simpler architecture and is generally easier to learn than Kubernetes, which has a much steeper learning curve.
Scalability: While both platforms support scaling, Docker becomes cumbersome and difficult to manage when attempting to manage a large number of containers. Kubernetes comes out on top when it comes to managing large-scale container deployments due to features such as auto-scaling and rolling updates.
Compatibility: Docker is compatible with most cloud platforms and operating systems, making it a versatile choice for various deployment environments. Kubernetes, on the other hand, is primarily designed for hybrid or on-premises cloud environments and can run completely in a cloud environment.
Choosing the Right Container Management Tool
The right container management tool depends on the nature of your organisation and projects. Several factors will influence whether Docker or Kubernetes is the more suitable solution. However, it’s important to note that Kubernetes can be used to complement Docker, and in many cases, it’s best to utilise both platforms.
Project size and complexity: If your organisation is working on a small project that requires a limited number of containers, Docker is likely the best option. Alternatively, if the project involves large-scale applications, Kubernetes is much better suited because it offers features such as auto-scaling and rolling updates.
Team expertise: Team members may already have experience using a containerisation platform such as Docker or Kubernetes. If several team members have experience using Kubernetes, for example, you may opt for this solution to save time spent on training.
Integration with tools and processes: The best containerisation tool for you will depend on the other tools and processes you and your team rely on to develop and manage software. For example, Docker has native support for a range of storage and networking options, which makes it easier to integrate with existing infrastructure.
Additionally, it’s important to consider the context for when it’s appropriate to use Kubernetes and when you should use Docker:
Docker: If the application is confined to a single host or server and does not require scaling out or communication with other applications, Docker would be more suitable.
Kubernetes: If the application requires multiple containers, needs to handle multiple requests, and should be resilient with no downtime, Kubernetes is a better option.
In Summary
Kubernetes and Docker are powerful containerisation tools, each with its advantages and drawbacks for organisations looking to utilise containers. Docker is generally viewed as a more straightforward, accessible tool for building and running small-scale containers, while Kubernetes is an advanced containerisation platform with a steep learning curve. However, Kubernetes is the best solution for orchestrating and managing containers in large-scale deployments. By understanding the differences between the two platforms, you can make an informed decision on which container management solution is best for your organisation’s unique requirements or if you should utilise both tools.