# Start an AWS Fault Injection Simulator experiment based on events

## Description
This samples contains an AWS Lambda function that starts an AWS Fault Injection Simulator experiment based on an Amazon EventBridge event. This allows you to do automated chaos engineering experiments using AWS FIS. Automation helps us cover a larger set of experiments than we can cover manually, and verifies our assumptions over time, as unknown parts of the system are changed.

## Deploy the sample application

The AWS SAM CLI is an extension of the AWS CLI that adds functionality for building and testing Lambda applications. To use the AWS SAM CLI, you need the following tools:

* AWS SAM CLI - [Install the AWS SAM CLI](https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-install.html).
* Node.js - [Install Node.js 14](https://nodejs.org/en/), including the npm package management tool.

To build and deploy your application for the first time, run the following in your shell:

```bash
sam build
sam deploy --guided
```

The first command will build the source of your application. The second command will package and deploy your application to AWS, with a series of prompts:

* **Stack Name**: The name of the stack to deploy to CloudFormation. This should be unique to your account and region, and a good starting point would be something matching your project name.
* **AWS Region**: The AWS region you want to deploy your app to.
* **Parameter ExperimentTemplateId**: The AWS FIS Experiment template Id to use.
* **Parameter EventPattern**: The Amazon EventBridge event pattern in JSON used to trigger the AWS Lambda function and start the experiment. Example event for successful launch of instance in auto scaling group:
```json
{"detail-type": ["EC2 Instance Launch Successful"],"source": ["aws.autoscaling"],"detail": {"AutoScalingGroupName": ["YOUR-AUTO-SCALING-GROUP-NAME"]}}
```
* **Confirm changes before deploy**: If set to yes, any change sets will be shown to you before execution for manual review. If set to no, the AWS SAM CLI will automatically deploy application changes.
* **Allow SAM CLI IAM role creation**: Many AWS SAM templates, including this example, create AWS IAM roles required for the AWS Lambda function(s) included to access AWS services. By default, these are scoped down to minimum required permissions. To deploy an AWS CloudFormation stack which creates or modifies IAM roles, the `CAPABILITY_IAM` value for `capabilities` must be provided. If permission isn't provided through this prompt, to deploy this example you must explicitly pass `--capabilities CAPABILITY_IAM` to the `sam deploy` command.
* **Save arguments to samconfig.toml**: If set to yes, your choices will be saved to a configuration file inside the project, so that in the future you can just re-run `sam deploy` without parameters to deploy changes to your application.

## Remove the sample application
Delete the CloudFormation stack via CLI:
```bash
aws cloudformation delete-stack --stack-name YOUR-STACK-NAME
```

## Security

See [CONTRIBUTING](../CONTRIBUTING.md#security-issue-notifications) for more information.

## License

This library is licensed under the MIT-0 License. See the LICENSE file.