Chapter 12. Cluster Federation and Multi-Tenancy

This chapter will discuss the new federation capabilities and how to use them to manage multiple clusters across cloud providers. We will also cover the federated version of the core constructs. We will walk you through federated Deployments, ReplicaSets, ConfigMaps, and Events.

This chapter will discuss the following topics:

• Federating clusters
• Federating multiple clusters
• Inspecting and controlling resources across multiple clusters
• Launching resources across multiple clusters

Technical requirements

You'll need to have your Google Cloud Platform account enabled and logged in, or you can use a local Minikube instance of Kubernetes. You can also use Play with Kubernetes over the web: https://labs.play-with-k8s.com/. There's also the Katacoda playground at https://www.katacoda.com/courses/kubernetes/playground.

You'll also need GitHub credentials, the setting up of which we'll go over later in this chapter. Here's the GitHub repository for this chapter: https://github.com/PacktPublishing/Getting-Started-with-Kubernetes-third-edition/tree/master/Code-files/Chapter12.

Introduction to federation

While federation is still very new in Kubernetes, it lays the groundwork for a highly sought after cross-cloud provider solution. Using federation, we can run multiple Kubernetes clusters on-premises and in one or more public cloud providers and manage applications utilizing the entire set of all our organizational resources.

This begins to create a path for avoiding cloud provider lock-in and highly available deployment that can place application servers in multiple clusters and allow for communication to other services located in single points among our federated clusters. We can improve isolation on outages at a particular provider or geographic location while providing greater flexibility for scaling and utilizing total infrastructure.

Currently, the federation plane supports these resources: ConfigMap, DaemonSets,Deployment,Events,Ingress,Namespaces,ReplicaSets,Secrets, and Services. Note that federation and its components are in alpha and beta phases of release...

Why federation?

There are several major advantages to taking on Kubernetes cluster federation. As mentioned previously, federation allows you increase the availability and tenancy capabilities of your Kubernetes clusters. By scaling across availability zones or regions of a single cloud service provider (CSP), or by scaling across multiple CSPs, federation takes the concept of high availability to the next level. Some term this global scheduling, which will could enable you to direct traffic in order to maximize an inexpensive CSP resource that becomes available in the spot market. You could also use global scheduling to relocate workloads cluster to end use populations, improving the performance of your applications.

There is also the opportunity to treat entire clusters as if they were Kubernetes objects, and deal with failure on a per-cluster basis instead of per machine. Cluster federation could allow operators to automatically recover from entire clusters failing by routing traffic to...

Setting up federation

While we can use the cluster we had running for the rest of the examples, I would highly recommend that you start fresh. The default naming of the clusters and contexts can be problematic for the federation system. Note that the --cluster-context and --secret-name flags are there to help you work around the default naming, but for first-time federation, it can still be confusing and less than straightforward.

 

Hence, starting fresh is how we will walk through the examples in this chapter. Either use new and separate cloud provider (AWS and/or GCE) accounts or tear down the current cluster and reset your Kubernetes control environment by running the following commands:

$ kubectl config unset contexts
$ kubectl config unset clusters

Double-check that nothing is listed using the following commands:

$ kubectl config get-contexts
$ kubectl config get-clusters

Next, we will want to get thekubefed command on our path and make it executable. Navigate back to the folder where you...

True multi-cloud

This is an exciting space to watch. As it grows, it gives us a really good start to doing multi-cloud implementations and providing redundancy across regions, data centers, and even cloud providers. 

While Kubernetes does provide an easy and exciting path to multi-cloud infrastructure, it's important to note that production multi-cloud requires much more than distributed deployments. A full set of capabilities from logging and monitoring to compliance and host-hardening, there is much to manage in a multi-provider setup. 

True multi-cloud adoption will require a well-planned architecture, and Kubernetes takes a big step forward in pursuing this goal.

 

Getting to multi-cloud

In this exercise, we're going to unite two clusters using Istio's multi-cloud feature. Normally, we'd create two clusters from scratch, across two CSPs, but for the purposes of exploring one single isolated concept at a time, we're going to use the GKE to spin up our clusters, so we can focus on the inner...

Summary

In this chapter, we looked at the new federation capabilities in Kubernetes. We saw how we can deploy clusters to multiple cloud providers and manage them from a single control plane. We also deployed an application across clusters in both AWS and GCE. While these features are new and still mainly in alpha and beta, we should now have the skills to utilize them as they evolve and become part of the standard Kubernetes operating model. 

In the next chapter, we will take a look at another advanced topic: security. We will cover the basics for secure containers and also how to secure your Kubernetes cluster. We will also look at the Secrets construct, which gives us the capability to store sensitive configuration data similar to our preceding ConfigMap example.

Questions

1. What is the main goal of federation?
2. What is the main advantage of using federation?
3. What are the building blocks of federation?
4. What is the Kubernetes CLI command that controls federation?
5. What are the two software components of Kubernetes federation?
6. What is the main difference between HPAs and federated HPAs?
7. What types of federated resources are available?

Further reading

If you'd like more information on mastering Kubernetes, check out another excellent Packt resource called Mastering Kubernetes (https://www.packtpub.com/application-development/mastering-kubernetes-second-edition).