Kubernetes Alternatives

Kubernetes is the market leader in distributed cluster orchestrators. Interestingly, a number of alternatives now exist to give Kubernetes a run for its money. Each has its own specific advantages and disadvantages, as well as different usage options: from a simple local cluster for your own development environment to a distributed system with tens of thousands of nodes. We’ll present the best solutions here.

Following the triumph of Docker as a platform for container virtualisation, Kubernetes established itself as the standard tool for container orchestration. However, Kubernetes’ features go far beyond managing groups of containers. Kubernetes automates deployment, management and scaling of containerised applications. Applications managed with Kubernetes are scalable and predictable. Kubernetes supports the following features:

• Automated rollout and rollback of changes
• Service discovery within the network
• Mass storage orchestration
• Scaling of applications and services
• Batch processing of data

Not all Kubernetes alternatives cover the entire spectrum of Kubernetes’ features, however many of the alternatives offer features beyond the scope of Kubernetes. The most popular ones integrate convenient features related to user management, monitoring, and security. Some of the alternatives use Kubernetes behind the scenes, while others can be used in conjunction with Kubernetes. Let’s first get an overview of the most important aspects of Kubernetes and its alternatives.

Different approaches exist for operating clusters and containers. The deployment parameters describe how resources are allocated and managed. They also determine the environments in which the systems can be set up and the types of applications that can be used:

To operate a cluster of containers, it is not enough to just manage them. A cluster is only fully functional and useful if other tasks are performed in addition to the management:

Kubernetes and its alternatives are software for managing distributed clusters. There are different approaches to structure this kind of system:

There are now several systems on the market that provide a service comparable to Kubernetes. We’ve distinguished between three large classes:

Furthermore, there are Kubernetes alternatives such as Apache Mesos and Azk, which do not fit into any of the three classes. We’ve taken a look at the following systems and compared them with Kubernetes:

• Docker Swarm
• Apache Mesos
• AWS Fargate
• OpenShift
• Rancher
• Nomad
• Azk

First, let’s start with a brief overview of Kubernetes.

Kubernetes enables the execution and orchestration of contained applications. The feature set includes cluster management, scheduling, service discovery, monitoring, and secret management. Kubernetes can be used to implement clusters of up to 5,000 nodes and 300,000 containers. Originally developed by Google, the software is now under the umbrellas of the Cloud Native Computing Foundation (CNCF). In addition to Google, industry giants such as Red Hat, Docker, and IBM are involved in its ongoing further development.

As an industry standard, Kubernetes implementations can be found in the public cloud infrastructures of major providers. New, useful developments and tools such as ‘minikube’, ‘kubeadm’ and ‘K3s’ are constantly being added. These provide convenient functions, simplify the installation and administration of Kubernetes and make the software possible on weaker hardware.

The biggest disadvantage of Kubernetes is the complexity of the software. A complete Kubernetes installation involves half a dozen interacting services. Setup requires some effort and the running software is resource-consuming.

Kubernetes is used for big data and machine learning projects that require the Kubernetes ecosystem or Helm charts. Due to the complexity of the software, Kubernetes is best suited for larger projects with a multi-year duration and a generous budget. If an in-house installation is operated, a full-time team should be available for administration. Alternatively, managed Kubernetes in a public cloud infrastructure works for many businesses.

Docker Swarm is Docker’s own tool for orchestrating clusters that consist of Docker engines. A Swarm cluster consists of Swarm manager nodes, which orchestrate and manage the cluster, and worker nodes, which are given jobs to process by the manager nodes.

The biggest advantage of Docker Swarm is the tight integration of the software into the Docker ecosystem. Once the Docker Engine is installed, you can start using Docker Swarm right away. For control, you’ll fall back on the familiar Docker command line interface. Docker Swarm interacts with the functionality of Docker and Docker Compose, using its own Swarm API. The software supports scaling, load balancing, service discovery, and multi-host networking.

In direct comparison with Kubernetes, Docker Swarm offers fewer options for customiszations and extensions. In general, the range of functions is smaller.

Docker Swarm is particularly well suited to handle smaller workloads. If an existing Docker environment exists, it can be easily leveraged with Docker Swarm to orchestrate container clusters.

Apache Mesos is based on the same principles as the Linux kernel. However, the two are implemented at a different level of abstraction. The Mesos kernel runs on every machine in the cluster and provides APIs for applications such as Hadoop, Spark, Kafka, and Elasticsearch. Mesos allows resource management and scheduling to be distributed across data centres and cloud environments.

Apache Mesos abstracts computing resources such as CPU, memory, and storage away from the actual machines. This allows clusters to scale to tens of thousands of nodes. Fault-tolerant, redundant manager and agent nodes are used, which are supplied with updates without interruption if required. Cloud-native and Legay applications can run side-by-side within a cluster. The software runs on Linux, macOS, and Windows and includes a web interface for managing clusters and containers.

Mesos is designed for systems with many clusters and high scalability. The software operates at a lower level of abstraction than Kubernetes. Thus, it is not as suited for small clusters with less than a dozen nodes.

Apache Mesos can be used to build fault-tolerant and elastically distributed systems. The software is particularly suitable for large systems that are designed for maximum redundancy.

AWS Fargate is a ‘serverless’ engine for containers and follows the container-as-a-service model. When using Fargate, the focus is on the application, rather than the infrastructure. Fargate takes care of the management of the required resources. The software uses the sister technologies Amazon Elastic Container Service (ECS) and Amazon Elastic Kubernetes Service (EKS).

The biggest advantage of AWS Fargate is its strong focus on the application layer. Since you don’t have to worry about provisioning the infrastructure, you don’t have the overhead associated with administering and scaling servers. Fargate scales the required resources elastically, so that no overprovisioning of servers for peak loads is needed. That way, you only pay for the computing capacity you actually use. Fargate stands out with integral application isolation for enhanced security.

AWS Fargate makes the use of Kubernetes more comfortable. However, this may also result in higher costs. Furthermore, the shielding of the user from the underlying technology means that there are fewer possibilities for control and influence.

AWS Fargate can be used to implement applications, APIs, microservices architectures, and data batch processing. Fargate runs containerised applications and scales them on demand. The software is also used for artificial intelligence (AI) and machine learning (ML) training.

The OpenShift platform from vendor Red Hat uses Kubernetes behind the scenes. OpenShift allows orchestration of containers and networks and enables scheduling and management of distributed, scalable resources. The software can be rolled out across multiple cloud environments. This includes private clouds on its own compute infrastructure, as well as Amazon AWS and Microsoft Azure cloud infrastructures.

OpenShift has a web interface on board to control functionality in addition to the obligatory command line tools. Following the GitOps model, developers are required to keep all configuration as code. Despite a similar name, OpenShift is not related to OpenStack.

The biggest advantage of OpenShift is that it provides development teams with a consistent and powerful working environment. Regardless of the environment used - public, private, or hybrid cloud - developers have the same approaches to building, testing, and running applications. This includes in particular the ‘OpenShift Pipelines’ a solution for continuous development.

Another strength of OpenShift is its built-in monitoring and logging tools. These include Prometheus for managing monitoring and notifications, Jaeger for transaction tracking, Kali for interfaces and visualisation, and Istion for implementing distributed microservice architectures. Furthermore, OpenShift accesses the ‘Red Hat Container Catalog’, which contains container images tested and certified by Red Hat.

Like many products from Red Hat, OpenShift relies on the commercial Linux distribution ‘Red Hat Enterprise Linux’ (RHEL). This dependency results in a certain Vendor Lock-In.

OpenShift is particularly suitable for implementing hybrid cloud strategies and building and scaling the containerised applications required for this. Organisations that are already part of the Red Hat ecosystem will benefit from using the software.

Rancher provides another alternative based on Kubernetes. The tool is a complete software stack for teams that rely on containers. It addresses the operational and security challenges of running multiple Kubernetes clusters. Rancher provides DevOps teams with a centralised control interface and unifies the management of all Kubernetes clusters in an organisation. Cluster provisioning, upgrades, and user and policy management are included in the feature set.

Rancher simplifies the deployment of Kubernetes clusters on physical machines, as well as in public and private cloud environments. Clusters are protected using global security policies; centralised systems are used for authentication, access control and traceability. The software prevents cluster failures and performs rescue and recovery operations as needed. Rancher works with various Linux and Kubernetes distributions, protecting against vendor lock-in. In terms of convenience features, Active Directory, LDAP and SAML support, as well as DNS provisioning are included.

In contrast to Kubernetes, the community around Rancher is considerably smaller. Furthermore, the software only runs on Linux.

Rancher is particularly well suited for managing multiple Kubernetes clusters with a centralised interface. User rights can be assigned across multiple clusters.

With Nomad an interesting tool for cluster management and scheduling is available from HashiCorp. The software can be used in conjunction with Kubernetes as well as a standalone alternative. Nomad joins the company’s existing range of cloud and provisioning software. Following the Unix philosophy, HashiCorp prefers a modular approach, with each tool covering a narrowly defined set of tasks. These include Terraform for infrastructure-as-code (IaC), Consul for service discovery, and Vault for secrets management.

In addition to the usual containerised applications, Nomad also supports virtualised as well as traditional ‘standalone’ applications. Unlike Kubernetes, Nomad does not consist of multiple, interacting system components. Rather, the software exists as a single, lightweight binary. This is deployed in local development environments, cloud environments, and private or public data centres.

Regardless of the deployed environment, Nomad provides the same operational convenience. It can be used to deploy clusters of tens of thousands of nodes across multiple availability zones, regions, and data centres. Multi-cluster deployments are also included in the feature set.

Since Nomad is a relatively new development, there is a much weaker ecosystem in contrast to Kubernetes. As a result, there are no Managed Nomad solutions from the major cloud providers.

Nomad is particularly well suited for small and medium-sized teams that lack the capacity to maintain a complex orchestrator. Nomad is also ideal when running a mix of containerised and non-containerised (Windows, Java) applications. The simplicity of the software allows teams to move quickly and respond to changing business needs.

With Azk, developers have an exciting Kubernetes alternative at their disposal. The tool installs locally and allows orchestration of development environments on your own machine. Azk provides a command-line interface; for each project, a configuration file (called Azkfile.js) is created that defines the development environment. This includes Docker container images, network and mass storage settings, and environment variables.

The biggest advantage of Azk is to make it easier for developers to set up local development environments. In addition to a central repository that contains images of the most used systems, the Azkfile file format is the main contributor to a good user experience. An Azkfile is written in an easy-to-understand JavaScript dialect and acts as a recipe for a local development environment. Furthermore, Azk offers the possibility to automatically generate an Azkfile based on some specifications.

Since Azk is mainly aimed at professional web developers, there is no support for Windows so far.

Azk is mainly suited to automate the installation and orchestration of development environments. This makes it possible to define consistent environments for different projects within a team.