> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.

# What is AWS FIS

> AWS Fault Injection Simulator is a managed service for running fault-injection experiments on AWS workloads to validate system resilience under failure scenarios.

In the world of Chaos Engineering, tools like Netflix’s [Chaos Monkey](https://github.com/Netflix/chaosmonkey) pioneered fault injection testing. Today, platforms such as Gremlin, Azure Chaos Studio, and **AWS Fault Injection Simulator (FIS)** help teams validate system resilience under real-world failure scenarios.

AWS FIS is a fully managed service that lets you run fault-injection experiments on AWS workloads. By deliberately introducing failures, you can:

* Identify weaknesses before they affect customers
* Validate auto-scaling, failover, and recovery processes
* Ensure SLAs are met under adverse conditions

<Callout icon="lightbulb" color="#1CB2FE">
  AWS FIS supports both simple and complex scenarios—from terminating individual EC2 instances to simulating an Availability Zone outage.
</Callout>

## Key Benefits

| Benefit                   | Description                                                         |
| ------------------------- | ------------------------------------------------------------------- |
| Fully Managed             | No need to provision infrastructure for fault injection             |
| Native AWS Integration    | Works with IAM, CloudWatch Alarms, AWS X-Ray, EventBridge, and more |
| Prebuilt & Customizable   | Use built-in templates or define your own experiments               |
| Multi-Environment Support | Inject faults in EC2, ECS, EKS, RDS, Lambda, and more               |

## AWS FIS Architecture

AWS FIS integrates seamlessly with your AWS environment:

* **CloudWatch Alarms**: Trigger experiments or remediation workflows when thresholds are crossed.
* **AWS X-Ray**: Correlate faults with distributed traces to pinpoint failures.
* **EventBridge**: Automate experiment scheduling and notifications.

<img src="https://mintlify.s3.us-west-1.amazonaws.com/kodekloud-c4ac6d9a/docs/Chaos-Engineering/Chaos-Engineering-Fundamentals/What-is-AWS-FIS/path/to/fis-architecture-diagram.png" alt="AWS FIS Architecture Diagram" />

You can leverage AWS FIS to simulate:

* EC2 instance terminations and CPU/network stress
* ECS and EKS pod failures
* RDS instance failovers
* Availability Zone outages
* Network latency and packet loss between resources

## Managing Experiments

AWS FIS experiments are defined as JSON documents. You can manage them through:

| Interface              | Command / Action                                      |
| ---------------------- | ----------------------------------------------------- |
| AWS Management Console | Create, configure, and run experiments via the web UI |
| AWS CLI                | `aws fis create-experiment-template`                  |
| AWS CloudFormation     | Use the `AWS::FIS::ExperimentTemplate` resource       |

```yaml theme={null}
# Example CloudFormation snippet
Resources:
  MyFISExperiment:
    Type: AWS::FIS::ExperimentTemplate
    Properties:
      Description: "Terminate EC2 instance for resilience testing"
      Actions:
        - ActionId: aws:ec2:terminate-instances
          Parameters:
            instanceIds: ["i-0123456789abcdef0"]
      Targets:
        - ResourceType: "aws:ec2:instance"
          ResourceTags:
            chaos-test: "true"
      RoleArn: arn:aws:iam::123456789012:role/FISRole
      StopConditions:
        - Source: "aws:cloudwatch:alarm"
          Value: arn:aws:cloudwatch:us-west-2:123456789012:alarm:HighCPUUtilization
```

<Callout icon="triangle-alert" color="#FF6B6B">
  Always run experiments in a staging or non-production environment first. Fault injection can cause service interruptions!
</Callout>

## Security & Permissions

Leverage **AWS Identity and Access Management (IAM)** to grant granular permissions:

* `fis:CreateExperimentTemplate`
* `fis:StartExperiment`
* `fis:StopExperiment`
* `cloudwatch:DescribeAlarms`
* `ec2:TerminateInstances`

Use IAM policies and roles to restrict who can create, modify, or execute FIS experiments.

***

## Links and References

* [AWS Fault Injection Simulator Documentation](https://docs.aws.amazon.com/fis/)
* [Chaos Engineering Concepts](https://chaosengineering.org/)
* [Amazon CloudWatch Alarms](https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/AlarmThatSendsEmail.html)
* [AWS X-Ray Overview](https://docs.aws.amazon.com/xray/latest/devguide/aws-xray.html)

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