Migrating from Docker Swarm to Kubernetes: A Case Study

Hello everyone! Today, I’m going to share an exciting story with you – how we decided to migrate from Docker Swarm to Kubernetes. You might be wondering: why make this change? Well, there are various reasons, and all of them add up to make Kubernetes a very appealing option. Let’s get into it!

Why the Change: Kubernetes Advantages over Docker Swarm

Docker Swarm is great, don’t get me wrong. It’s easy to use, has a gentle learning curve, and deployments are quick. However, if you’re looking for a tool with greater scalability, robustness, and flexibility, Kubernetes is your guy.

On the one hand, Kubernetes takes the trophy when it comes to scalability. Its ability to handle a large number of containers in a cluster is something that Kubernetes excels at. And if you add the possibility of managing several clusters at once, we have an indisputable winner.

Moreover, Kubernetes boasts a rich and diverse ecosystem. It offers a wide range of plugins and extensions, greatly increasing its flexibility. On top of that, the community that backs it is very active, with constant updates and improvements. In contrast, the Docker Swarm community, although dedicated, can’t compete in terms of size and activity.

Our Scenario: Where We Started

We were in a situation where we had already implemented Docker Swarm in our infrastructure. We had several services running on Swarm, which worked well and served their purpose. But we knew we could improve our architecture.

The Path to Kubernetes: First Steps

The first step to migrating from Docker Swarm to Kubernetes is creating a Kubernetes cluster. In our case, we chose to use Google Kubernetes Engine (GKE) for its ease of use and powerful functionalities. However, there are other options, like AWS EKS or Azure AKS, that you might also consider.

Once we created our cluster, we set to work on converting our Docker Compose Files to Kubernetes. This is where Helm comes in. Helm is a package manager for Kubernetes that allows us to define, install, and upgrade applications easily.

From Swarm to Cluster: Conversions and Configurations

Converting Docker Compose files to Helm files isn’t tricky, but it does require attention to detail. Luckily, there are tools like Kompose that make our lives easier. Kompose automatically converts Docker Compose files into Kubernetes files.

Once we converted our files, it was time to define our configurations. Kubernetes’ ConfigMaps and Secrets are the equivalent to environment variables in Docker Swarm. Here, we needed to make some modifications, but in general, the process was quite straightforward.

Deploying on Kubernetes: Challenges Faced

Now, with our Kubernetes cluster ready and our Helm files prepared, it was time to deploy our services. This is where we encountered some challenges.

The first challenge was managing network traffic. Unlike Docker Swarm, which uses an overlay network to connect all nodes, Kubernetes uses a different approach called CNI (Container Network Interface). This required a change in our network configuration.

Additionally, we had to adjust our firewall rules to allow traffic between the different Kubernetes services. Fortunately, Kubernetes’ Network Policies made this task easier.

The next challenge was managing volumes. While Docker Swarm uses volumes for persistent storage, Kubernetes uses Persistent Volumes and Persistent Volume Claims. While the concept is similar, the implementation differs somewhat.

In our case, we used Docker volumes to store data from our databases. When migrating to Kubernetes, we had to convert these volumes into Persistent Volumes, which required some additional work.

Finally, we faced the challenge of monitoring our new Kubernetes cluster. Although there are many tools for monitoring Kubernetes, choosing the right one can be complicated.

In our case, we opted for Prometheus and Grafana. Prometheus provides us with a powerful monitoring and alerting solution, while Grafana allows us to visualize the data in an attractive way.

Surprises Along the Way: What We Didn’t Expect

As with any project, we ran into a few surprises along the way. Some of them were pleasant, others not so much.

On one hand, we were pleasantly surprised by how easily we could scale our services on Kubernetes. Thanks to the auto-scaling function, we were able to automatically adjust the number of pods based on workload. This allowed us to improve the performance of our services and save resources.

On the other hand, we encountered some issues with updates. Unlike Docker Swarm, where updates are quite straightforward, in Kubernetes we had to grapple with Rolling Updates. Although they are a powerful feature, they require some practice to master.

Mission Accomplished!: Kubernetes Up and Running

Finally, after overcoming challenges and learning from surprises, we successfully migrated from Docker Swarm to Kubernetes. Now, our services run more efficiently, and we have greater flexibility and control over our infrastructure.

I’m sure that we still have a lot to learn about Kubernetes. But, without a doubt, this first step has been worth it. The migration has allowed us to improve our architecture, optimize our services, and prepare for future challenges.

And you, have you considered migrating from Docker Swarm to Kubernetes? What do you think of our experience? We’re eager to hear your impressions and learn from your experiences!