Multi-tenancy of a cluster is to share multiple tasks or user load. Shared clusters save overall costs and make administration simple. But the word “tenant” does not have any specific definition. It generally means sharing services and resources with multiple clients. Clients may be dependent on multiple teams or customer usage.
Cloud resources are storage, computing, and networking power. Here, each tenant’s data remains isolated. That means they are not visible to other tenants like an apartment. Each tenant has a unique key to their apartment. They can enter their apartment but can not enter other rooms. Nowadays, multi-tenancy in the Kubernetes model has become a common strategy.
In this article, we will learn what Kubernetes multi tenancy is and why we don’t use other alternatives, and much more. So, let’s get started!
What is Kubernetes Multi-Tenancy?
We all know that Kubernetes orchestrates the containers of an app to scale it according to the user-declared configuration. Kubernetes cluster helps to maintain the workload to give a smooth operation. Nowadays organizations use a single Kubernetes cluster that has multiple workloads.
These workloads are sharing the platform’s infrastructure. This sharing simplifies the management system and minimizes the cost of the cluster running. So, sharing a single cluster’s resources for multiple tenants is known as a multi-tenancy strategy. And Kubernetes multi-tenancy is a model to fit different types of users in the same cluster, optimize infrastructure, and hosts the workloads of multiple apps.
Kubernetes Multi Tenancy vs its Alternatives
Simply a tenant can be users or apps that want to remain in isolation from other users or apps in the cluster. Some people might think that multi-tenancy doesn’t want Kubernetes’ special feature requirements. So, why don’t we run the tenants on the different clusters? This process has some drawbacks.
In the case of a very large system, you may need thousands of tenants. So, you have to use a tool to manage these tenants. If you have too many clusters, then the situation will sink into more complexity. This will also result in resource efficiency issues for so many clusters. For this, we need to pay the control plane cost. The control plane will consume more resources than before.
A pod can use the free resources in one cluster. If the pods are carrying small-size apps, then the remaining space gets unused for one cluster. If you are running different small apps on different clusters, then the spaces will not be used. Because the alternative approach can not share anything with them. This is called fragmentation.
Also, you need to create a new cluster each time you attach a new tenant. This will make the process slow and costly. That is why multi-tenancy alternatives are not practically used. Everyone is using Kubernetes with Kubernetes multi-tenancy support.
Implementing Multi Tenant SaaS on Kubernetes
To implement SaaS apps on Kubernetes, you need to have a better understanding of the containers and Kubernetes, particularly the pods and deployment secrets. Kubernetes supports multi-tenants perfectly in a single cluster. First, you have to create namespaces. Namespaces are logical ways to organize clusters into virtual sub-clusters.
Now, let’s look at the concept to implement multi-tenant features to SaaS on Kubernetes.
Creating and configuring tenants
After you create namespaces, implement the logic for the given tenant using Kubernetes deployment according to the assigned namespace. You can build tenant isolation into the logic of single apps, and run tenants in their own cluster or own Kubernetes namespaces.
Here the deployments are dedicated to a single instrument reseller namespace and define the parameters or URL as they fit. Each tenant in the SaaS platform is connected to its own database. This database is defined within the Kubernetes cluster through these URLs.
The pods use init containers that run ahead of the primary containers. It proceeds with data seeding, where it provides some initial data to view the app’s condition in first-time runtime. So, you use the init container in each pod replica, and the deployment will try to seed the data source in the replica starting.
Finally, with proper configuration, you will have a tenant up and running with proper configuration commands. But, you have to be careful to wire up everything.
Does Kubernetes support Multi Tenant architecture?
People are still thinking about whether Kubernetes really supports multi-tenant fully on regular basis. That is because people think that users can’t use multi-tenancy out of the box with Kubernetes. You will need excess tools and configuration. The real things are
- Kubernetes is not a platform, is a building area for platforms. You need to build directly into its API to work with Kubernetes.
- Kubernetes has Namespaces, and service accounts to provide or separate workloads by a logical boundary.
So, we understand that Kubernetes is not PaaS (Platform as a Service). Kubernetes build platforms for your needs. It is not true that it doesn’t have a proper multi-tenant configuration, but it has the right foundation to build a process. That is because the different organization uses different strategies such as approval model, active directory groups, etc.
That is why Kubernetes doesn’t supply the full multi-tenant feature. Rather, it provides a strategy to shape the plans according to demand. Kubernetes is just one part of the platform.
Kubernetes helps you to get a multi-tenant system for the betterment of the system. But you have to know your demands and situation first, like how multi-tenancy works with the CI/CD pipeline, container registry, monitoring solutions, etc. before declaring the right multi-tenant for your cluster.
In the end, multi-tenancy gets rid of the need for each user to handle all infrastructure tasks like updates, maintenance, accessing, etc. on their own. This also allows multiple users to use or share the same resources. This also isolates the data from each other. Also, the Kubernetes resource called “Secret” makes the password and data both available and secure in the central database.