Docker Compose vs. Kubernetes: The Top 4 Main Differences

Application deployment is cumbersome. Every project requires a specific set of tools and libraries to run correctly. Developers spend hours structuring the perfect environment during the development phase. However, when it's time to shift the project to a new server, the entire effort must take place again.

Docker helps create a portable environment. It is an open-source tool that isolates your project in the form of a container and helps with mobility. It stores your application and environment in the form of images. Since Docker uses the host OS Kernel, these images can be deployed to any new hardware of the same architecture. 

What Is Docker Compose?

Docker Compose is a tool that makes it possible for you to run multi-container Docker applications defined using the Compose file format. With a Compose file, you can create and start all of the services defined in your configuration with a single command. It is important to note that Compose works in all environments, including production, staging, development, testing, and continuous integration workflows.

What Is Kubernetes? 

Kubernetes, known as K8s, refers to an open-source system to deploy, scale, and manage containerized applications anywhere. It assembles containers that make up an application into logical units to make their management and discovery easy. All this is possible thanks to its built-in commands for deploying applications, rolling out changes to your applications, scaling your applications up and down to fit changing needs, and monitoring your applications, to name a few.

Why Do You Need Orchestration Tools?

It goes without question that modern applications are highly complex, especially since the popular micro-services architecture treats one application as multiple more minor services. While this is good for Development, each service requires its own Docker container. Managing various containers can be counterproductive as DevOps Engineers have to worry about keeping the containers up and running. 

As a result, instead of having ease of deployment, developers are faced with a new challenge. This is where container orchestration tools come in handy, as they facilitate managing the status and coordination of multiple containers. Essentially, orchestration tools overlook your entire container since containers are inherently lightweight and require constant management. 

For Software Engineers, container orchestration tools are beneficial for Developers as they offer:

• Provisioning and deployment: Multiple containers can be created and deployed in a single workflow.
• Scheduling: Schedule to start, stop, and restart containers simultaneously.
• Container communication: It allows containers to communicate easily with each other o the following the network.
• Load Balancing: Ensures the correct distribution of workloads among containers.
• Security: Additional governance of the containers enhances their security.

Taking care of all these tasks is a nightmare. Thankfully, orchestration tools save you time and effort and make application deployment easier.

The simplest Docker utility for managing containers available is Docker Compose. It offers multi-container management with a few easy steps. Additionally, it's easy to configure and use but offers limited functionality. 

On the other hand, the most popular container orchestration tool is Kubernetes. Kubernetes is so widely adopted that it has become the industry standard. In fact, available data shows that the Kubernetes adoption rate stands at 88% as of 2022. It provides many benefits over Docker Compose, which explains why most software engineers favor it.

Comparing Docker Compose vs. Kubernetes

Docker Compose manages Docker containers using YAML configuration files. Once Docker builds all the containers, Compose brings them together as a single service. Containers within this service run in isolated environments but can communicate with each other.

Earlier, we highlighted the multiple benefits that an orchestration service provides. Docker Compose only covers a handful of them. Kubernetes, on the other hand, provides many more benefits for its users. Some of the key ones include:

1. Multi-Node Management

Docker Compose is designed to run containers on a single host system. In contrast, Kubernetes can manage containers deployed across multiple nodes(computers). This makes Kubernetes useful for large-scale applications and a large number of developers.

2. Pod Architecture 

A pod is the smallest, most basic deployable object in Kubernetes. A pod can contain one or multiple containers and adds an administration layer to the Kubernetes cluster. The pod architecture allows Kubernetes to offer many additional benefits.

3. Auto-Scaling

Each pod is provisioned on a Worker. The Worker has to compute resources like CPU units and memory bytes. It's essential to note that two pods can live on the same Worker. Horizontal scaling means the number of pods increases to manage the additional load and is scaled down to the minimum configured value when the load decreases.

4. Self-Healing Containers

When a container fails to respond to pre-defined health checks, Kubernetes automatically restarts it. This adds automation to the cluster as you do not have to check for pod failures constantly. These features make Kubernetes the ideal orchestration tool and the go-to choice for developers.

As an additional point, there are tools that facilitate migrating from Docker Compose to Kubernetes if a need arises. These tools analyze your Docker Compose YAML files and automatically convert them into Kubernetes artifacts. One such tool is Move2Kube. It is an open-source command line tool that accelerates the migration to Kubernetes.

Kubernetes also offers an easy migration tool called Kompose. Kompose makes the 'docker-compose. yaml' files compatible with 'kubectl.' 

Before talking about Kompose, let's discuss whether migration is a good idea for you.

Should I Migrate From Docker Compose to Kubernetes?

Docker Compose may not offer a lot in terms of features, but its simplicity of deployment is resourceful for many. All the configurations are stored in a single YAML file which is used to start or stop multiple containers. However, the primary difference between these orchestration tools is their host environment. If your application is small-scale and runs on a single host, then Docker Compose will work best for you.

You may also never require features like auto-scaling for a small application; manual management is simple. Nonetheless, this is not practical for most applications built today. As businesses grow, they acquire a larger client base. This leads to increased load on the web application, which calls for multi-node systems for maximum output and load balancing. Application health monitoring has also become a necessity for continuous operations.

In such a scenario, shifting to Kubernetes becomes obvious.

What Are the Possible Challenges of Migrating From Docker Compose to Kubernetes?

Shifting to Kubernetes will require several minor tweaks to the software. Since Compose only deals with single-host applications, mapping configurations to Kubernetes's multi-node architecture becomes tricky. It involves establishing container-to-container communication over the network via a network mesh. 

Furthermore, the application itself needs restructuring to fit into the Kubernetes ecosystem. This is down to the fact that Kubernetes comes with the features such as the pod architecture, which requires the application to communicate with Kubernetes for monitoring. Essentially, the migration process is not exactly smooth, and many errors are to be expected. Luckily tools like Kompose take care of a major chunk of the process. 

Let's see how 'Kompose' facilitates migration.

Migrating From Docker Compose to Kubernetes With Kompose

Working with Kompose is quite straightforward. The complete documentation can be found here.

Requirements

To begin, you need a Kubernetes cluster and the kubectl command line tools.

The Kubernetes cluster must be configured before moving on to the migration process. 

Note that Kompose is available for Windows, Linux, and macOS. Windows installation is completed by running the following command in the terminal:

`curl -L https://github.com/kubernetes/kompose/releases/download/v1.26.0/kompose-windows-amd64.exe -o kompose.exe`

Getting Started

Once installed, navigate to the directory where you have your `docker-compose.yaml` file and run the `kompose convert` command in the terminal. This command will create multiple YAML configuration files for Kubernetes from the original Compose file.

Finally, run the `kubectl apply` command to create the resources in Kubernetes.

That is all. You can now access all your services in Kubernetes. Another way to migrate is by using the `kompose up` command. Provided all Compose files are correctly configured, this command will automatically deploy your Docker Compose app to the Kubernetes cluster.

This tutorial is elementary and only serves as an introduction. In reality, complete migration may require other configurations and commands depending on your application and use case.

Conclusion

Choosing appropriate deployment tools can take time and effort. Ending up on the wrong platform can bring unnecessary complexities in terms of time and resources. Talking to field experts can help understand possibilities and explore the best options available.