Route Certificate Manager 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 GKE service that is triggered by a direct Certificate Manager event. For more details, see the list of supported direct events.

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. In the Event provider list, select Certificate Manager.

    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 list, from the Direct event type, select an event.
  7. 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.

  8. In the Region list, select global (Global).

    For more information, see Eventarc locations.

  9. If applicable to the event provider, click Add filter and specify the following:
    1. In the Attribute 1 field, depending on the direct event you chose, select a resource ID that can act as an event filter.
    2. Select an operator:
    3. In the Attribute value 1 field, depending on the operator that you chose, type the exact value or apply a path pattern.
    4. If an Attribute 2 field is applicable, specify the appropriate values.
  10. 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.

  11. In the Event destination list, select Kubernetes Engine.
  12. 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.

  13. 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.

  14. Click Create.
  15. 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=global \
      --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=EVENT_FILTER_TYPE" \
      --event-filters="COLLECTION_ID=RESOURCE_ID" \
      --event-filters-path-pattern="COLLECTION_ID=PATH_PATTERN" \
      --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
  • 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.
  • EVENT_FILTER_TYPE: the identifier of the event. An event is generated when an API call for the method succeeds. For long-running operations, the event is only generated at the end of the operation, and only if the action is performed successfully. For a list of supported event types, see Event types supported by Eventarc.
  • COLLECTION_ID (optional): the resource component that can act as an event filter, and is one of the following:
    • certificate
    • certificateissuanceconfig
    • certificatemap
    • certificatemapentry
    • dnsauthorization
  • RESOURCE_ID: the identifier of the resource used as the filtering value for the associated collection. For more information, see Resource ID.
  • PATH_PATTERN: the path pattern to apply when filtering for the resource.
  • 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:

  • The --location flag must be global. For more information, see Eventarc locations.
  • The --event-filters="type=EVENT_FILTER_TYPE" flag is required. If no other event filter is set, events for all resources are matched.
  • EVENT_FILTER_TYPE cannot be changed after creation. To change EVENT_FILTER_TYPE, create a new trigger and delete the old one.
  • 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; however, when using the --event-filters-path-pattern flag, you can define a resource path pattern.
  • 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=global \
      --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.certificatemanager.certificate.v1.updated" \
      --event-filters-path-pattern="certificate=my-certificate-*" \
      --service-account=${SERVICE_ACCOUNT_NAME}@${PROJECT_ID}.iam.gserviceaccount.com

This command creates a trigger called helloworld-trigger for the event identified as google.cloud.certificatemanager.certificate.v1.updated and matches events for certificate IDs starting with my-certificate-.

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