How do you design a fault injection framework that is scalable and reusable?

1 Define your goals and metrics

Before you start injecting faults, you need to have a clear idea of what you want to achieve and how you will measure it. What are the failure modes and scenarios that you want to simulate? What are the expected behaviors and outcomes of your system under stress? How will you monitor and analyze the impact of the faults on your system's availability, performance, security, and functionality? Define your goals and metrics upfront, and align them with your business and technical requirements.

2 Choose your fault injection methods and tools

There are different ways to inject faults into a system, such as modifying inputs, outputs, or states, altering network conditions, corrupting data, or crashing processes. Depending on your system's architecture and components, you may need to use different methods and tools to achieve your desired effects. For example, you can use chaos engineering platforms, such as Chaos Monkey or Gremlin, to inject faults at the infrastructure or service level, or you can use code-level libraries, such as Byteman or Simoorg, to inject faults at the application or database level. Choose your fault injection methods and tools based on your system's characteristics, complexity, and testability.

3 Design your fault injection scenarios and policies

Once you have your fault injection methods and tools, you need to design your fault injection scenarios and policies. A scenario is a set of fault injection actions that target a specific component or function of your system, such as a service, an API, a database, or a network link. A policy is a set of rules that define when, where, how, and how often to execute a fault injection scenario, such as the frequency, duration, intensity, and scope of the faults. Design your fault injection scenarios and policies based on your goals and metrics, and make sure they are realistic, relevant, and representative of your system's environment and workload.

4 Implement your fault injection framework

To implement your fault injection framework, you need to integrate your fault injection methods and tools with your system's code, configuration, and deployment. You also need to ensure that your fault injection framework is modular, configurable, and extensible, so you can easily add, modify, or remove fault injection scenarios and policies without affecting your system's functionality or stability. Moreover, you need to ensure that your fault injection framework is secure, isolated, and controllable, so you can prevent unauthorized or unintended access, interference, or leakage of faults or data.

5 Execute and evaluate your fault injection experiments

The final step is to execute and evaluate your fault injection experiments. You need to run your fault injection scenarios and policies according to your plan, and observe and collect data on your system's behavior and performance under stress. You also need to compare and analyze the data against your goals and metrics, and identify any gaps, anomalies, or improvements. Based on the results, you can validate or invalidate your assumptions, hypotheses, or expectations, and decide whether you need to adjust or repeat your fault injection experiments.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?