Route audit log events to Google Kubernetes Engine (GKE)

An Eventarc trigger declares your interest in a certain event or set of events. You can configure event routing by specifying filters for the trigger, including the event source, and the target Google Kubernetes Engine service running in a GKE cluster. Note that targets can include the public endpoints of private and public services running in a GKE cluster.

Eventarc delivers events to the event receiver in a CloudEvents format through an HTTP request.

These instructions show you how to configure event routing to your Cloud Run service that is triggered when an audit log is created that matches the trigger's filter criteria. For a list of the audit log events supported by Eventarc, including serviceName and methodName values, see Event types supported by Eventarc.

For more information about capturing events that are triggered when an audit log is created that matches the trigger's filter criteria, see Determine event filters for Cloud Audit Logs.

Before you begin

You must enable Workload Identity on the GKE cluster that the destination service is running on. Workload Identity is required to properly set up the event forwarder and is the recommended way to access Google Cloud services from applications running within GKE due to its improved security properties and manageability.

Eventarc events to GKE targets architecture

Workload Identity

Applications running on GKE might need access to Google Cloud APIs. Workload Identity allows a Kubernetes service account in your GKE cluster to act as an IAM service account. Pods that use the configured Kubernetes service account automatically authenticate as the IAM service account when accessing Google Cloud APIs. Using Workload Identity allows you to assign distinct, fine-grained identities and authorization for each application in your cluster. Note that specific permissions must be granted to the Eventarc trigger's service account. In this document, see the steps to Create a service account.

Workload Identity is also needed to forward Cloud Run for Anthos events using Eventarc. For more information on enabling and configuring Workload Identity on your GKE clusters, refer to Use Workload Identity.

Event forwarder

Eventarc's event forwarder pulls new events from Eventarc and forwards them to the GKE destination. This component acts as a mediator between the Pub/Sub transport layer and the GKE service. It works on existing services and also supports signaling services (including those not exposed outside of the fully-managed cluster) while simplifying setup and maintenance. At a networking level, to receive events in a GKE service, you don't need to open the service to external traffic as all events are delivered from an origin that resides within the same GKE cluster.

Note that the event forwarder's lifecycle is managed by Eventarc, and if you accidentally delete the event forwarder, Eventarc will restore this component.

For each trigger pointing to a GKE destination, the event forwarder (a specifically configured gke-forwarder pod) does the following:

  1. It uses the Pub/Sub API to open a StreamingPull connection to the trigger transporter (a Pub/Sub topic and subscription) and receives events as they become available.

  2. It transforms events to the correct CloudEvents format and encodes and delivers them as an HTTP POST request to the target GKE service.

The Eventarc service agent needs the permission to run and regularly update the gke-forwarder instance. This permission must be granted once-per-project. For details, in this document, see Enable GKE destinations.

Prepare to create a trigger

For each trigger that targets a GKE service, Eventarc creates an event forwarder component. Eventarc requires permissions to install the component and manage resources in the GKE cluster. Before creating an Eventarc trigger for GKE destinations, ensure that you complete the following tasks.

Console

  1. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

    Go to project selector

  2. Enable the Eventarc, Eventarc Publishing, Google Kubernetes Engine, and Resource Manager APIs.

    Enable the APIs

  3. If applicable, enable the API related to the events. For example, for Cloud Functions events, enable cloudfunctions.googleapis.com.

  4. If you don't already have one, create a user-managed service account, then grant it the roles and permissions necessary so that Eventarc can manage events for your target service.

    1. In the Google Cloud console, go to the Create service account page.

      Go to Create service account

    2. Select your project.

    3. In the Service account name field, enter a name. The Google Cloud console fills in the Service account ID field based on this name.

      In the Service account description field, enter a description. For example, Service account for event trigger.

    4. Click Create and continue.

    5. To provide appropriate access, in the Select a role list, select the required Identity and Access Management (IAM) roles to grant to your service account. For more information, see Roles and permissions for GKE targets.

      For additional roles, click Add another role and add each additional role.

    6. Click Continue.

    7. To finish creating the account, click Done.

gcloud

  1. In the Google Cloud console, activate Cloud Shell.

    Activate Cloud Shell

    At the bottom of the Google Cloud console, a Cloud Shell session starts and displays a command-line prompt. Cloud Shell is a shell environment with the Google Cloud CLI already installed and with values already set for your current project. It can take a few seconds for the session to initialize.

  2. Enable the Eventarc, Eventarc Publishing, Google Kubernetes Engine, and Resource Manager APIs.

    gcloud services enable eventarc.googleapis.com \
        eventarcpublishing.googleapis.com \
        container.googleapis.com \
        cloudresourcemanager.googleapis.com
  3. If applicable, enable the API related to the direct events. For example, for Cloud Functions events, enable cloudfunctions.googleapis.com.

  4. If you don't already have one, create a user-managed service account, then grant it the roles and permissions necessary so that Eventarc can manage events for your target GKE destination.

    1. Create the service account:

      gcloud iam service-accounts create SERVICE_ACCOUNT_NAME
      

      Replace SERVICE_ACCOUNT_NAME with the name of the service account. It must be between 6 and 30 characters, and can contain lowercase alphanumeric characters and dashes. After you create a service account, you cannot change its name.

    2. Grant the required Identity and Access Management (IAM) roles or permissions. For more information, see Roles and permissions for GKE targets.

Enable GKE destinations

To allow Eventarc to manage resources in the GKE cluster, enable GKE destinations, and bind the Eventarc service agent with the required roles.

  1. Enable GKE destinations for Eventarc:

    gcloud eventarc gke-destinations init
    
  2. At the prompt to bind the required roles, enter y.

    The following roles are bound:

    • roles/compute.viewer
    • roles/container.developer
    • roles/iam.serviceAccountAdmin

Create a trigger

You can create an Eventarc trigger using the Google Cloud CLI or through the Google Cloud console.

Console

  1. In the Google Cloud console, go to the Eventarc Triggers page.

    Go to Triggers

  2. Click Create trigger.
  3. Type a Trigger name.

    This is the ID of the trigger and it must start with a letter. It can contain up to 63 lowercase letters, numbers, or hyphens.

  4. For the Trigger type, select Google sources.
  5. Select an Event provider.

    This is the Google service that is the source of events through its audit logs. For example, select BigQuery.

    Note that the event provider name used in the associated Google Cloud documentation might not have a prefix of Cloud or Google Cloud. For example, on the console, Memorystore for Redis is referred to as Google Cloud Memorystore for Redis.

  6. In the Event type list, from the via Cloud Audit Logs events, select an event type.
  7. Select one of the following:
    • Any resource—This is the default and includes dynamically created resources that have identifiers generated at creation time.
    • Specific resource—You must provide the full resource name.
    • Path pattern—You can filter for resources using a path pattern. For example, type projects/_/buckets/eventarc-bucket/objects/random.txt or type projects/_/buckets/**/r*.txt.
  8. To specify the encoding of the event payload, in the Event data content type list, select application/json or application/protobuf.

    Note that an event payload formatted in JSON is larger than one formatted in Protobuf. This might impact reliability depending on your event destination and its limits on event size. For more information, see Known issues.

  9. In the Region list, select a region.

    Cloud Audit Logs triggers for Eventarc are available in specific regions and in the global region, but are not available in dual-region and multi-region locations. To avoid any performance and data residency issues caused by a global trigger, Google recommends that the location match that of the Google Cloud service that is generating events. For more information, see Eventarc locations.

    If you specify the global location, you will receive events from all locations yielding matches for the event filters. For example, by creating a global Eventarc trigger, you can receive events from resources in the EU and US multi-regions.

    Note that there is a known issue with Cloud Audit Logs triggers for Compute Engine that results in events originating from a single region: us-central1. This is regardless of where the virtual machine instance is actually located. When creating your trigger, set the trigger location to either us-central1 or global.

  10. ?
  11. Select the Service account that will invoke your service or workflow.

    Or, you can create a new service account.

    This specifies the Identity and Access Management (IAM) service account email associated with the trigger and to which you previously granted specific roles required by Eventarc.

  12. In the Event destination list, select Cloud Run.
  13. Select a service.

    This is the name of the service that receives the events for the trigger. The service must be in the same project as the trigger and will receive events as HTTP POST requests sent to its root URL path (/), whenever the event is generated.

  14. Optionally, you can specify the Service URL path to send the incoming request to.

    This is the relative path on the destination service to which the events for the trigger should be sent. For example: /, /route, route, route/subroute.

  15. Click Create.
  16. After a trigger is created, the event source filters cannot be modified. Instead, create a new trigger and delete the old one. For more information, see Manage triggers.

gcloud

You can create a trigger by running a gcloud eventarc triggers create command along with required and optional flags.

gcloud eventarc triggers create TRIGGER \
    --location=LOCATION \
    --destination-gke-cluster=DESTINATION_GKE_CLUSTER \
    --destination-gke-location=DESTINATION_GKE_LOCATION \
    --destination-gke-namespace=DESTINATION_GKE_NAMESPACE \
    --destination-gke-service=DESTINATION_GKE_SERVICE \
    --destination-gke-path=DESTINATION_GKE_PATH \
    --event-filters="type=google.cloud.audit.log.v1.written" \
    --event-filters="serviceName=SERVICE_NAME" \
    --event-filters="methodName=METHOD_NAME" \
    --event-data-content-type="EVENT_DATA_CONTENT_TYPE" \
    --service-account=SERVICE_ACCOUNT_NAME@PROJECT_ID.iam.gserviceaccount.com

Replace the following:

  • TRIGGER: the ID of the trigger or a fully qualified identifier
  • LOCATION: the location of the Eventarc trigger. Alternatively, you can set the eventarc/location property; for example gcloud config set eventarc/location us-central1.

    Cloud Audit Logs triggers for Eventarc are available in specific regions and in the global region, but are not available in dual-region and multi-region locations. To avoid any performance and data residency issues caused by a global trigger, Google recommends that the location match that of the Google Cloud service that is generating events. For more information, see Eventarc locations.

    If you specify the global location, you will receive events from all locations yielding matches for the event filters. For example, by creating a global Eventarc trigger, you can receive events from resources in the EU and US multi-regions.

    Note that there is a known issue with Cloud Audit Logs triggers for Compute Engine that results in events originating from a single region: us-central1. This is regardless of where the virtual machine instance is actually located. When creating your trigger, set the trigger location to either us-central1 or global.

  • DESTINATION_GKE_CLUSTER: the name of the GKE cluster in which the target GKE service that receives events is running.
  • DESTINATION_GKE_LOCATION: (optional) the location in which the destination GKE service can be found. If not specified, it is assumed that the service is in the same region as the trigger. For more information see Cloud Run for Anthos on Google Cloud locations.
  • DESTINATION_GKE_NAMESPACE: (optional) the namespace in which the destination GKE service is running. If not specified, the default namespace is used.
  • DESTINATION_GKE_SERVICE: the name of the GKE service that receives the events for the trigger. The service can be in any of the GKE supported locations and does not need to be in the same location as the trigger. However, the service must be in the same project as the trigger and will receive events as HTTP POST requests sent to its root URL path (/), whenever the event is generated.
  • DESTINATION_GKE_PATH: (optional) the relative path you specify on the destination GKE service to which the events for the trigger should be sent. For example: /, /route, route, route/subroute.
  • SERVICE_NAME: the identifier of the Google Cloud service
  • METHOD_NAME: the identifier of the operation
  • EVENT_DATA_CONTENT_TYPE: (optional) the encoding of the event payload. This can be application/json or application/protobuf. The default encoding is application/json.

    Note that an event payload formatted in JSON is larger than one formatted in Protobuf. This might impact reliability depending on your event destination and its limits on event size. For more information, see Known issues.

  • SERVICE_ACCOUNT_NAME: the name of your user-managed service account.
  • PROJECT_ID: your Google Cloud project ID.

Notes:

  • These flags are required:

    • --event-filters="type=google.cloud.audit.log.v1.written"
    • --event-filters="serviceName=VALUE"
    • --event-filters="methodName=VALUE"
  • Optionally, filter events for a specific resource by using the --event-filters="resourceName=VALUE" flag and specifying the complete path to the resource. Omit the flag for dynamically created resources that have identifiers generated at creation time. Or, filter events for a set of resources by using the --event-filters-path-pattern="resourceName=VALUE" flag and specifying the resource path pattern.

  • Each trigger can have multiple event filters, comma delimited in one --event-filters=[ATTRIBUTE=VALUE,...] flag, or you can repeat the flag to add more filters. Only events that match all the filters are sent to the destination. Wildcards and regular expressions are not supported.
  • After a trigger is created, the event filter type can't be changed. For a different event type, you must create a new trigger and delete the old one.
  • The --service-account flag is used to specify the Identity and Access Management (IAM) service account email associated with the trigger.

Example:

  gcloud eventarc triggers create helloworld-trigger \
      --location=us-central1 \
      --destination-gke-cluster=gke-events-cluster \
      --destination-gke-location=us-central1-a \
      --destination-gke-namespace=default \
      --destination-gke-service=helloworld-events \
      --destination-gke-path=/ \
      --event-filters="type=google.cloud.audit.log.v1.written" \
      --event-filters="serviceName=bigquery.googleapis.com" \
      --event-filters="methodName=google.cloud.bigquery.v2.JobService.InsertJob" \
      --service-account=${SERVICE_ACCOUNT_NAME}@${PROJECT_ID}.iam.gserviceaccount.com

This creates a trigger called helloworld-trigger for audit logs that are written by bigquery.googleapis.com and for the operation identified as google.cloud.bigquery.v2.JobService.InsertJob.

Terraform

You can create a trigger for a GKE destination using Terraform. For details, see Create a trigger using Terraform.

List a trigger

You can confirm the creation of a trigger by listing Eventarc triggers using the Google Cloud CLI or through the Google Cloud console.

Console

  1. In the Google Cloud console, go to the Eventarc Triggers page.

    Go to Triggers

    This page lists your triggers in all locations, and includes details such as names, regions, event providers, destinations, and more.

  2. To filter your triggers:

    1. Click Filter or the Filter triggers field.
    2. In the Properties list, select an option to filter the triggers by.

    You can select a single property or use the logical operator OR to add more properties.

  3. To sort your triggers, beside any supported column heading, click Sort.

gcloud

Run the following command to list your triggers:

gcloud eventarc triggers list --location=-

This command lists your triggers in all locations, and includes details such as names, types, destinations, and statuses.

What's next