Secure cron jobs with VPC Service Controls

VPC Service Controls is a Google Cloud feature that lets you set up a secure perimeter to guard against data exfiltration. This guide shows you how to include Cloud Scheduler jobs in a VPC Service Controls perimeter.

Limitations

The following limitations apply to VPC Service Controls support for Cloud Scheduler.

Enforced actions

VPC Service Controls is enforced on the following actions:

• Cloud Scheduler job creations
• Cloud Scheduler job updates

Why does this matter?

Because VPC Service Controls is enforced only on job creations and updates, VPC Service Controls is not automatically enforced for jobs that were created before you added Cloud Scheduler to your VPC Service Controls perimeter. Jobs continue to execute even if the job targets are not part of your VPC Service Controls perimeter or are not supported targets. To enforce VPC Service Controls for all Cloud Scheduler jobs:

• Jobs with targets that are either unsupported or are outside your perimeter: Delete the jobs. In this document, see Delete non-compliant jobs.
• Jobs with targets that are both supported and inside your perimeter: Run an update on each job after adding Cloud Scheduler to your perimeter. In this document, see Enforce VPC Service Controls on pre-existing jobs.

Supported targets

The Cloud Scheduler integration with VPC Service Controls supports the following targets. HTTP endpoints are supported if listed; however, arbitrary HTTP endpoints are not supported.

• Cloud Run services—must use the canonical default run.app domain. Custom domains and custom DNS are not supported and will cause job creation to fail.
• Cloud Run functions—must use the canonical default cloudfunctions.net or run.app domain. Custom domains and custom DNS are not supported and will cause job creation to fail.

• Google Cloud APIs that are VPC Service Controls-compliant (either in Preview or GA) can be in a different Google Cloud project from your Cloud Scheduler job.

  • You must use the global endpoint format (https://SERVICE.googleapis.com). Regional endpoints—such as *.rep.googleapis.com, LOCATION.SERVICE.googleapis.com, and REGION-SERVICE.googleapis.com—and mTLS endpoints (*.mtls.googleapis.com) are rejected.

  • For Cloud Run jobs, the supported URI format is the following: https://run.googleapis.com/v2/projects/PROJECT_ID/locations/REGION/jobs/JOB_NAME:run

    To learn about the difference between Cloud Run service and job resources, see Services, jobs, worker pools, and instances: four ways to run your code.

• Pub/Sub

Unsupported targets

When Cloud Scheduler is a restricted service in your VPC Service Controls perimeter, any attempt to create or update a job with an unsupported target will fail with a TARGET_TYPE_NOT_PERMITTED_FOR_VPC error code. This action does not generate a violation log when using dry run mode.

Custom domains (such as external application load balancers or custom DNS) for serverless endpoints are not supported targets. Runtime invocations to custom domains are blocked by the destination service due to missing in-perimeter credentials, even for pre-existing jobs created before the perimeter enrollment.

To avoid unexpectedly blocking your workloads, delete any jobs with unsupported targets or with targets outside of the VPC Service Controls perimeter you plan to use, before moving your perimeter to enforced mode.

Delete non-compliant jobs

Recommended. Delete Cloud Scheduler jobs with targets that are either:

• Unsupported (see Supported targets)
• Outside of the VPC Service Controls perimeter you plan to use

For instructions on deleting jobs, see Delete a job.

If you don't delete these jobs before adding Cloud Scheduler to your VPC Service Controls perimeter, the jobs continue to run, but VPC Service Controls is not enforced on them. In this document, see Enforced actions.

For example, if you have a Cloud Scheduler job that targets an unsupported target (such as an arbitrary HTTP endpoint), the job continues to run after you add Cloud Scheduler to your VPC Service Controls perimeter, but it is not protected by VPC Service Controls. The same is true for a pre-existing job with a target outside of your VPC Service Controls perimeter. However, if a pre-existing job targets a serverless custom domain inside your perimeter, the destination service blocks runtime invocations.

Add required IAM roles

Required. In order to use VPC Service Controls, the Cloud Scheduler service account must have the Cloud Scheduler Service Agent IAM role. The Cloud Scheduler service account is created for your project automatically. To verify that it has the Cloud Scheduler Service Agent IAM role, or to grant this role, take the following steps:

1. In the Google Cloud console, go to IAM.

   Go to IAM

2. Select the Include Google-provided role grants checkbox.

3. In the filter, type Cloud Scheduler Service Account, and select this principal.

4. Look at the Role column for the Cloud Scheduler Service Account principal. You can proceed if the following role is listed:

   • Cloud Scheduler Service Agent

   If the Cloud Scheduler Service Account role is not listed, click the Edit icon and grant the Cloud Scheduler Service Agent role to the Cloud Scheduler Service Account principal.

Specify a VPC Service Controls perimeter

Required. You can use an existing perimeter or create a new perimeter to protect your Cloud Scheduler jobs that have supported targets. Both approaches give you the chance to specify services to restrict. Specify the Cloud Scheduler API.

• Existing perimeters: To update an existing VPC Service Controls perimeter to include Cloud Scheduler, follow the steps to update a service perimeter.

• New perimeters: To create a new perimeter for Cloud Scheduler, follow the steps to create a service perimeter.

Enforce VPC Service Controls on pre-existing jobs

Recommended. To enforce VPC Service Controls on Cloud Scheduler jobs that you created before you added Cloud Scheduler to your VPC Service Controls perimeter, run an update on the job. You don't have to change the job, but you must run the update for VPC Service Controls to apply to the job and its future executions.

You can run an update for the job using the Google Cloud console (select the job and click Edit), the API, or the gcloud CLI.

To enforce VPC Service Controls on a pre-existing job by using the gcloud CLI, run the following:

HTTP targets

gcloud scheduler jobs update http JOB_ID

Replace JOB_ID with the ID of your job.

Pub/Sub targets

gcloud scheduler jobs update pubsub JOB_ID

Replace JOB_ID with the ID of your job.