If you’re trying to decide which container orchestration tools you want to use, Docker Swarm, Kubernetes, and Apache Mesos are sure to be at the top of your list. So, which should you choose?
Container orchestration tools are essentially used to assist you in integrating and managing containers, typically at a larger scale. Docker is clearly the winner when it comes to the number of people who use them for containerization, but choosing the cluster manager varies between these top choices.
Many developers automatically choose Swarm because it is from Docker, the container system that they likely already use, but this doesn’t mean that it’s the best choice. While it’s relatively new, it’s gaining features quickly and fairly devoid of bugs. Also, because of the number of developers that use Docker products, Swarm has a large community attached to it.
Google’s Kubernetes is the most popular container orchestration system right now. It has a lot of support from major companies that like the ease of use. There’s also a large community on GitHub supporting Kubernetes. It’s quite opinionated, but certainly not by an overwhelming amount -- arguably, quite less so than Swarm.
Mesos, meanwhile, has a much different approach than Swarm and Kubernetes. Many features are customizable by the user by adding plugins and outside applications rather than being built into the cluster manager itself.
So, with Mesos, you can have a much more customized deployment, but you really need to know what you’re doing.
Now, we’ll talk a little bit more in depth about each of these main management tools, then help point you in the right direction as to which might be best for you.
If you’re already using Docker, it won’t take you long to understand Swarm. Swarm acts as the Docker API, so all of the tools you’ve already been using with Docker can utilize Swarm to scale throughout a number of different hosts.
Docker Swarm clusters multiple Docker engines into one virtual engine natively. Swarm is able to scale up to 50,000 containers and 1,000 nodes without any noticeable effects. Your performance will run virtually just as quickly and smoothly as you continue adding containers up to these numbers.
If you can’t choose between Swarm, Mesos or Kubernetes, it is actually possible to run Swarm as a frontend Docker client as you simultaneously run one of the other container managers in the backend.
When Docker Swarm released version 1.12, it was integrated into the core, so the product is very opinionated now, but it also brings many features through the Docker API.
Kubernetes has the full power of Google behind it, managing containerized applications across many hosts. It has many tools and resources to help you deploy, scale, and maintain your applications.
The way Kubernetes functions is by using pods that group into containers, then scheduling and deploying them at the same time. While most other container management services use a container as their minimum unit, Kubernetes uses the pods.
These pods are quickly updated, built, or destroyed in real-time depending on the situation. Kubernetes can be used on private, public, multi-cloud, and hybrid cloud environments.
This product is fully open source, so, as you can image, it has many added features to make it quite extendable and is very open to third-party resources. It’s a fair bit more automated than Docker Swarm, with features such as auto-replication and auto-placement, so Kubernetes is very accessible.
Mesos is a bit different from the other services mentioned in this article. It’s an open-source cluster manager that focuses on isolating resources and sharing across distributed applications, networks, or frameworks.
Managers are able to share resources, improving the utilization of clusters. Any Linux program has the ability to run on Mesos, which runs on every machine with one machine as the master that controls the others.
Mesos is essentially an abstraction layer for computing elements. It provides further safeguarding against failures, can handle thousands of hosts, and uses multiple agent nodes to run tasks. The master will see the available resources through the agents, then distribute tasks to available agents.
Mesos itself as an underlying infrastructure is not opinionated at all, so almost any needs can be fulfilled by going down a level.
So, which is best?
As always, it depends on your project and scale. You can even use these services in conjunction with one another. For example, Mesos doesn’t even necessarily have to be containers. If you choose, it could simply be a chroot sandbox alignment.
If you want a full container management service that includes scheduling, automatic scaling, health monitoring, and regular updates, Kubernetes is the way to go. Docker Swarm, instead, focuses on letting you work from a single Docker engine to view a systemwide view of a cluster.
When using Swarm, you’ll be dependent on Docker, but chances are, you probably use Docker for your containers anyways. If not, the dependence on Docker is something you’ll want to consider before committing to Swarm. Docker Native is additionally not the best choice for very large-scale applications.
Mesos and Kubernetes both were created to help applications run in clustered environments, although Kubernetes has a stronger focus on running clusters, has more features, and is the older product. On the other hand, it’s also quite opinionated.
So, if you agree with the Google opinions or don’t have specific ways you’d like to layout clusters, Kubernetes is a good choice that takes care of many of the behind-the-scenes chores for you.
Mesos, meanwhile, has much more flexibility, stronger scheduling features, and is able to work with a wider variety of schedulers, and has been modified from its original creation to have better support for containers.
Non-Docker and noncontainerized applications can run on Mesos and it is able to handle very complicated workloads that will slowly shift to containers. It has also been tested to tens of thousands of nodes, proving strong scalability and underlying infrastructure. But you need to be more confident using this product at this scale, as you’ll need to manage load balancing and other advanced scaling features yourself.
After you figure out exactly what your needs are, you’ll be able to find the perfect container orchestration tools for you.
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