Painless Docker - 2nd Edition

Docker Swarm Limitations, Challenges & Use Cases

The decision to force MySQL to run on a specific node resolved the issue of data persistence, but it introduced another problem: what happens if the node fails? In that case, the service will become unavailable.

Additionally, if we want to scale up our database or set up a high availability (HA) MySQL system with masters and replicas, it's not possible with a single MySQL instance.

Swarm Mode itself doesn't handle the scalability of stateful applications like databases, so it's the responsibility of the user to address this. To tackle this challenge, we need to use a MySQL clustering solution that can handle the replication and failover of MySQL instances. The solution should be designed to work with Docker Swarm and should be able to handle the dynamic nature of the cluster, where nodes can be added or removed. The challenge is to find a solution that is compatible with Docker Swarm and is maintained and supported by the community. In this regard, the tools and platforms developed around Docker Swarm are not as mature as those developed around Kubernetes; some of them are not actively maintained, and some of them are not production-ready. Since the ecosystem of orchestration tools is Kubernetes-dominated, most of the efforts in developing tools for stateful applications are focused on Kubernetes, and there are not many options available for Docker Swarm.

This is applicable not only to MySQL but also to the whole ecosystem: logging tools, service meshes, monitoring tools, and so on. This is one of the main reasons why Docker Swarm is not as popular as Kubernetes, and why it's not widely adopted in production environments.

Although Kubernetes is the most popular container orchestration tool, Docker Swarm remains a viable choice for many use cases. Here are some advantages of Docker Swarm over Kubernetes:

• Docker Swarm is easier to set up and use compared to Kubernetes.
• Docker Swarm is more lightweight than Kubernetes.
• Docker Swarm is more accessible than Kubernetes.
• Docker Swarm is built into Docker Engine.