Configuring Real-Time events

This section details the steps required to set up AWS Event Handlers. Alternatively, you can use the aws_setup baseline which automates this process.

The Guardrails Event Handlers are responsible for conveying events from AWS CloudTrail back to Guardrails for processing. This is a requirement for Guardrails to process and respond in real-time. However, if your organization has more complex requirements that forbid the use of the Event driven model, Event Pollers can be used. Event Handlers and Event Pollers enable Guardrails' Event-driven model of operation.

Guardrails uses the following infrastructure for event handling:

  • CloudTrail must be enabled in every region where events are to be sent from. This can be done with regional, global or Organization trails. An additional Cloudtrail just for Guardrails' use is unnecessary cost.
  • EventBridge is enabled by default and requires no configuration. Guardrails uses the 'default' bus.
  • CloudWatch Event Rules determine which API events to filter for.
  • CloudWatch Event Targets Direct the events from EventBridge to SNS.
  • SNS Topic Where the events are published.
  • SNS Subscription Forwards events to the event ingestion API endpoint where Guardrails will process them.

Guardrails Mods Required for Event Handling

In order to configure real time eventing, the following set of mods must be installed and up to date in the environment:

Required for AWS Account Import

  • aws
  • aws-iam
  • aws-kms

Required for Guardrails configuration of CloudTrail

These mods are required only if using Guardrails to configure CloudTrail.

  • aws-cloudtrail
  • aws-s3

Required for Event Handler configuration

  • aws-events
  • aws-sns

Configuring CloudTrail

You are not required to use the Guardrails Audit Trail to configure CloudTrail, but there must be a CloudTrail configured in each region or a global trail.

The Guardrails Audit Trail policy provides a convenient mechanism for setting up CloudTrail in AWS accounts.

Creating logging buckets using the default configuration

CloudTrail requires an S3 bucket to store logs. The Guardrails Logging Bucket policy can simplify creation of logging buckets.

To set up logging buckets in the default configuration, simply set the AWS > Turbot > Logging > Bucket policy to Enforce: Configured.

# Create AWS logging buckets
# AWS > Turbot > Logging > Bucket
resource "turbot_policy_setting" "loggingBucket" {
resource = "id of parent folder or smart folder" //highlight-line
type = "tmod:@turbot/aws#/policy/types/loggingBucket"
value = "Enforce: Configured"

The default configuration will create a logging bucket in each region of your AWS account. If desired, you can modify the behavior of this stack to match your logging strategy through the AWS > Turbot > Logging > Bucket > * sub-policies.

Verify the state of AWS > Turbot > Logging > Bucket control for each region. They will be in the OK state when completed.

Note: If using AWS > Turbot > Logging > Bucket in preparation for AWS > Turbot > Audit Trail, be aware that logging buckets will be deployed in all regions specified in the AWS > Account > Approved Regions [Default] policy. The Turbot Audit Trail will only be deployed in a single region. Use AWS > Turbot > Logging > Bucket > Regions to specify which regions will get logging buckets.

Set up CloudTrail with the default configuration:

Once the logging buckets have been created, it is time to set up the Audit Trail stack:

# AWS > Turbot > Audit Trail
resource "turbot_policy_setting" "auditTrail" {
resource = "id of parent folder or smart folder" //highlight-line
type = "tmod:@turbot/aws#/policy/types/auditTrail"
value = "Enforce: Configured"

The default configuration will create a global trail in us-east-1, though users can use the AWS > Turbot > Audit Trail > * sub-policies to customize the CloudTrail configuration to meet requirements.

Verify the state of AWS > Turbot > Audit Trail control for each region. They will be in the OK state when completed.

Configuring Event Handlers

Workspace Configuration

Here are the Turbot > Workspace policies relevant to event handling for SaaS and Enterprise customers. If desired, these policies should be configured before enabling event handling.

Enterprise Specific Policies

Enterprise API GW Configuration

For enterprises with a private Turbot console, an API gateway must be used. The hostname of the API Gateway must be specified in the Turbot > Workspace > Gateway Domain Name policy. Typically, the domain name will be gateway.{installation_domain_name}. (The installation domain name is taken from the value specified in the Turbot Enterprise Foundation (TEF) stack.)

However, some enterprise environments cannot use gateway.{installation_domain_name}, usually because of DNS resolution complexity or enterprise policy. A viable option is to use the AWS API Gateway domain name instead, since it is always publicly resolvable. Follow these steps to retrieve the appropriate hostname then set it in Turbot:

  1. In the Turbot Master's account, go to the AWS API Gateway console. Find the Turbot API Gateway.
  2. Go to APIs. Click into turbot-api or {resource_prefix}-api. Click into Stages then click the turbot stage.
  3. From the top of the turbot stage page, grab the "Invoke URL". It will be in the form of https://{uniqueId}.execute-api.{region} The /turbot path is required. Do not add a / after /turbot. Strip off https://
  4. Copy the stage URL to the Gateway Domain Name policy. It should be in this form: {uniqueId}.execute-api.{region}
  5. If Event Handling has been enabled, let the event handler source policies recalculate then Event Handler control run again. Otherwise, complete the steps outlined in the rest of this document then return to this procedure.
  6. Examine the SNS Subscription in the Event Handler control logs to make sure it confirmed properly.

Enabling Event Handlers

To set up AWS Event Handlers in the default configuration, in the Turbot console, set the AWS > Turbot > Event Handler policy to Enforce: Configured. The below Terraform can also be used.

# AWS > Turbot > Event Handlers
resource "turbot_policy_setting" "eventHandlers" {
resource = "id of parent folder or smart folder" //highlight-line
type = "tmod:@turbot/aws#/policy/types/eventHandlers"
value = "Enforce: Configured"

The default configuration will set up event handlers in all enabled regions. Users can use the AWS > Turbot Event Handlers > * sub-policies to customize the configuration to meet requirements.

Verify that the AWS > Turbot > Event Handlers controls are in ok for each region. Deployment often takes a minute or two per region. If not in ok then use the information in How Event Handlers Work to get a sense of what may have gone wrong in the deployment.

Decomissioning Event Handlers

Event handlers can be shut-off by setting the AWS > Turbot > Event Handler policy to Enforce: Not configured. Turbot will perform the required Terraform runs to destroy the event handler infrastructure. Note: Deleting an AWS account out of Turbot will not automatically decommission the event handlers. Event Handlers must be set explicitly destroyed before removing the account from Turbot.

When to decommission Event Handlers

Event Handlers should be decommissioned before:

  • Destroying the AWS account itself
  • Removing the account from Turbot supervision.
  • Switching to AWS Event Pollers. Processing of duplicate events is highly undesirable.
  • Event Handling is no longer desired for this account or region.

Relationship to AWS Event Pollers

Note that AWS Event Pollers operate based on the value of AWS > Turbot > Event Handler policy setting, not on the state of the Event Handler controls themselves. By default, Event Handling is disabled so the event pollers run automatically. After Event Handling is enabled, the event pollers will stop running.

Event Handlers in Error

It is possible for the event handler controls to be in an error state because of incorrect configuration, permissions issues, etc. With event handling enabled, the event pollers won't run. Until these problems are resolved, events from the environment may be lost. Resolve problems with event handlers as quickly as possible.

Duplicate Events

It is also possible to get duplicate events if Event Pollers are explicitly enabled along with Event Handlers. Event Handlers and Event Pollers should never be enabled at the same time.

Event Handlers Bulk Changes

Occasionally, event handler configuration needs a bulk change. This can come from a number of sources:

  • Initial rollout of event handlers.
  • Workspace configuration change.
  • Installation, update or removal of a new AWS mod.
  • Changes to EC2 or VPC CMDB policies. Other mods may have specific event handling based on CMDB policies but not always.
  • Websecret Key Rotation

Turbot will make these changes as fast as possible. Each update to the event handlers requires at least one Terraform run, sometimes more. For changes in larger environments, it's possible that a particular event handler control cannot get a Terraform container before the timeout. When this happens, the event handler control will go into an error state. Turbot will retry these errors over time.


The best source of troubleshooting information is in the AWS > Turbot > Event Handler control logs.

  • Permissions Issues: If the permissions granted to the Turbot IAM role do not allow configuration of event rules and SNS topics, then the logs will indicate access denied.
  • SCP Regional Restrictions: Many enterprises use Service Control Policies to restrict region usage. SCPs restrictions will appear as "Access Denied" errors in the Turbot console. Work with your SCP admins to determine which regions are permitted then update the AWS > Account > Regions policy to match.
  • SNS Subscription won't confirm: Check the various Turbot > Workspace policies that they are properly configured. Ensure that resources in the Turbot Master VPC can resolve the ALB's hostname.


Congrats! Event handlers are now configured in the target account. To verify that they are working correctly, create a new resource or change an existing resource. Turbot will receive the event which will trigger relevant controls. If resource creation or modification events do not get picked up by Turbot, feel free to reach out to

How Event Handlers Work

When troubleshooting events handlers, it helps to know how they work. This section will describe the Turbot and AWS halves of event handlers.

Turbot Policies and Stacks

Turbot uses Terraform to deploy the various pieces of AWS event handling infrastructure. The Terraform source that defines all event handling infrastructure is compiled from several sources. They are:

  • Workspace configuration policies: These policies specify information like the HTTPS endpoint that event handlers should point to, or the webhook secrets that should be sent with each event.
  • Regions: AWS event handlers are deployed on a per-region basis. If some regions are locked out by SCP, or are just out of scope, these regions should be excluded from the AWS > Account > Regions policy. (Note, AWS > Account > Regions is a different policy than AWS > Account > Approved Regions [Default]. The Regions policy defines the scope of where Turbot will look for resources. The Approved Regions policy states where resources are allowed to exist.)
  • Event Handler configuration policies: Enable event handlers. Specify resource prefixes for SNS topics, and Event Rules. Specify SNS encryption at rest. See AWS > Turbot > Event Handlers > * for more configuration options.
  • Installed mods: Turbot will interrogate the list of mods then build a set of event rules to capture the relevant events. See the Mods tab on the Admin page for a full list of installed mods.
  • Resource CMDB policies: In the case of EC2 and VPC, disabling certain CMDB policies will remove the relevant events from the CloudWatch event rules.

All of these input sources are brought together in the read-only AWS > Turbot > Event Handlers > Source policy value. Looking at the "Depends On" tab of the Event Handlers > Source policy shows all the dependent policies and values. Errors in any of these policies may prevent event handlers from deploying or updating properly. The value of AWS > Turbot > Event Handlers > Sources is Terraform.

AWS Resources (CloudTrail through to Turbot Events Container)

Events in an AWS region pass through several services on their way to Turbot. The path is:

  1. CloudTrail: If CloudTrail isn't setup for a region, event handling cannot happen. CloudTrail is the source of events to be sent to Turbot.
  2. CloudWatch Event Rules: Event Rules filter the raw CloudTrail events down to those that Turbot needs. (For example, if the aws-cloudfront mod is not installed, there's no need to get cloudfront:* events. Some events such as s3:PutObject can be extremely high volume but worthless to Turbot.)
  3. SNS Topic: After filtering by Cloudwatch Event Rules, events are placed on the turbot_event_handler SNS topic to send back to Turbot.
  4. SNS Subscription: An HTTPS subscription sends events back to the Turbot.
  5. (optional) API Gateway and Events Proxy: Some enterprise customers with private ALBs will deploy an API Gateway to make the transition from a public API endpoint to a private ALB. The Events Proxy Lambda function passes an event from the non-VPC API gateway to the VPC bound ALB. Turbot SaaS customers do not have this step.
  6. Turbot ALB: The common entry point for events and API calls.
  7. Turbot Events Container: Events are processed here, triggering CMDB updates, or control runs.