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Kubernetes fire drills – a common practice for Cleura Business and Enterprise customers

June 7, 2023

As the adoption of Kubernetes continues to grow, its critical role in ensuring business continuity has become abundantly clear, not least by the sheer nature of being the technology that runs such a considerable portion of our digital lives.

Kubernetes is an inherently complex technology designed to solve complex problems, and failures can occur at all levels, from nodes and pods to entire clusters. Regular fire drills on your Kubernetes environment are essential to maximize your chances of withstanding failures and improve your chances of coming out unscathed on the other side.

This article briefly discusses our reasoning and high-level thinking in and around Kubernetes fire drills. We apply these practices with our Business and Enterprise customers to help them achieve their business objectives with container orchestration in Cleura Cloud. We base this article and some of our methods and technical capabilities on our container orchestration engine, Gardener, and Kubernetes. However, the general principles outlined here apply to any microservice environment.

What is a Kubernetes Fire Drill?

Fire drills on Kubernetes environments are exercises that simulate different failures to test an environment’s resiliency and validate a recovery plan.

In helping our clients with fire drills, we generally go through five main stages, regularly learning new lessons and drawing more and more knowledge from:

  1. Preparation
  2. Define the scope.
  3. Simulate a failure.
  4. Activate the recovery plan.
  5. Validate the recovery.
  6. Conduct a post-mortem.

Cleura Container Orchestration Engine

Our Container Orchestration Engine, Gardener, is a Kubernetes-based platform that enables Cleura Cloud users to manage multiple Kubernetes clusters. Gardener provides several features that make it easier to conduct fire drills in a Kubernetes environment, including the ability to perform maintenance tasks, such as gracefully shutting down a node or a cluster. These features allow users to simulate a failure without impacting the production environment.

Performing a Kubernetes fire drill

1. Preparation – involve all stakeholders.

It sounds simple, but involving all potential stakeholders will ensure you cover as many critical areas as possible in the disaster recovery plan. Each stakeholder has a unique perspective and knowledge of the business processes they are responsible for, and they can help identify potential vulnerabilities and suggest additional recovery steps.

For example, if the team was developing a disaster recovery plan for an e-commerce website, involving stakeholders from the marketing team would help ensure that customer data and marketing campaigns are fully protected in the event of a disaster. Also, in this example, the marketing team would be the ones who are most qualified to answer wether or not the recovery plan did the trick.

2. Define the scope

Before we do anything else, clearly defining the fire drill’s scope is essential. It should include which type of failure we will simulate, which services will suffer what impact, and the recovery plan we will use to mediate the problem. Both developers, operations personnel, and business owners need to be part of defining the scope to ensure that it covers all vital areas.

Here is an example of a high-level, real-life scope from a fire drill we practiced with one of our clients. We stick to the high-level points in the scope to give a good overview.

Example of scope

  1. Simulate a sudden increase in traffic to the Kubernetes cluster by throwing many requests to the applications running on the cluster.
  2. Monitor the cluster’s response to the increased traffic and identify performance issues or bottlenecks.
  3. Test the cluster’s ability to handle a node failure by simulating the loss of one or more nodes in the cluster.
  4. Observe the cluster’s response to the node failure and ensure the applications run smoothly.
  5. Verify that the Kubernetes autoscaling mechanisms are working correctly by adding additional nodes and observing the cluster’s ability to handle the increased load.
  6. Document the results of the fire drill and identify any areas for improvement or optimization.

3. Simulate the failure(s)

The next step is to simulate the failure according to the scope of the drill. It could be as easy as manufacturing a high load or a node failure, as illustrated in our example scope, to be as complicated as your team likes the scenario to be.

Choosing what types of failures to practice depends entirely on how well you want your team and systems to handle different scenarios. We think keeping a healthy balance between accomplishing fire drills and improving the systems is essential, and our best tip is to limit your failure types to core backend components and expand when you get into the habit of exercising fire drills.

4. Activate the recovery plan

When your simulated scenario is activated, it’s time to start the recovery plan that you have already outlined in Step 1. The recovery plan should be well-defined and documented to cover all critical areas.

Some of the features in our container orchestration engine, Gardener, such as the ability to recover from backup or perform a rolling upgrade, can be used to recover from the failure. Other scenarios might need restoring network connectivity and relying on Kubernetes self-healing properties.

5. Validate the recovery

The last step is to validate that the recovery plan restored the system to its original state.

Besides checking the overall status of the cluster, including its nodes and system components, you need to verify the health and performance of the applications deployed on the cluster. Data consistency should also be critical to your recovery plan, especially for stateful applications or applications that persist data. Other practical tests include ensuring that your monitoring and logging services are functioning correctly and that your cluster can, once again, handle auto-scaling in response to increased workloads after recovering.

We keep coming back to the stakeholders but don’t forget to involve all of them in the validation process to ensure that as many areas as possible are covered.

6. Document a post-mortem

After the fire drill, it is time to conduct a post-mortem to evaluate the effectiveness of the recovery plan and identify any areas for improvement. Use the findings from the post-mortem to update the recovery plan and improve your system’s resiliency. 

Conducting regular fire drills in a Kubernetes environment, perhaps using our container orchestration engine, Gardener, is essential to ensure your system and staff are better prepared to handle failures.

The steps outlined in this article provide a rough framework for conducting effective fire drills in a Kubernetes environment. By following these steps, you, too, can identify and fix any major issues before an actual disaster strikes.

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Martin Dahl
Customer Solutions Architect at Cleura
Karlskrona, Sweden

With over a decade in the field, Martin Dahl is an accomplished Solutions Architect specializing in containers, Kubernetes, and OpenStack.

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