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Nested Kubernetes with Loft
Matryoshka
Kubernetes is considered the frontrunner when it comes to container orchestration, and no matter where you look, no potential successor is in sight – regardless of the flavor, whether OpenShift, Rancher, or plain vanilla Kubernetes. If you run containers, you will find it difficult to avoid fleet management with Kubernetes – not least because former alternatives such as Docker Swarm have now become virtually irrelevant.
Kubernetes' popularity admittedly also means that admins don't have much choice if they are dissatisfied with the platform – and admins can find many things not to like. One often-cited criticism, for example, is the traditionally poor support for multiple tenants. In fact, the solution was never designed to manage the containers of many clients in parallel – a curse and a blessing at the same time: A blessing because Kubernetes is far less complex than OpenStack, for example, where multitenancy was part of the strategy right from the start, and a curse because the fairly mediocre multitenant support means that operating Kubernetes clusters can quickly get out of hand.
Because it doesn't make sense to create a full Kubernetes setup right away for every test scenario, Kubernetes developers have given some thought to multitenancy over the past few years. They now rely on namespaces to separate the workloads of different users and projects in a Kubernetes cluster. If this reminds you of namespaces in the Linux kernel, you are right: Parts of Kubernetes' isolation solution are at least inspired by Linux kernel namespaces, and they are also used quite tangibly in that Kubernetes relies on the kernel feature to isolate different projects from each other on the target systems.
Most admins agree that namespaces in Kubernetes are not a full-fledged substitute for true multitenancy. (See the "The Namespaces Challenge" box.) However, the truth is, they were never supposed to be. A platform for Kubernetes self-service and
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