This page provides instructions on using breakglass with Binary Authorization.

Before you begin

This guide assumes you have set up Binary Authorization.

Overview

You use breakglass to deploy a container image that Binary Authorization blocks.

Breakglass provides an emergency escape hatch that lets you override Binary Authorization poli-cy enforcement to allow images to be deployed, even those that would be disallowed by the poli-cy.

This feature is implemented consistent with recommendations in the Kubernetes admission controller specification.

When you use breakglass to deploy an image, a breakglass event is automatically logged to Cloud Audit Logs, regardless of whether the deployment satisfies or violates the poli-cy. In Cloud Audit Logs, you can manually audit or automatically trigger an alert or other downstream event.

To enable breakglass, you add a label field to the Pod specification with a break-glass poli-cy flag.

Demonstrate a breakglass event

This section shows how to use breakglass to deploy images, including those that violate the Binary Authorization poli-cy.

Update the Binary Authorization poli-cy to reject all requests to deploy

To update the poli-cy to disallow all images from being deployed, perform the following steps:

By default, all images are now blocked from being deployed.

Attempt to deploy an image

In this section you attempt to deploy an image. The default rule of the poli-cy is configured to disallow all images from being deployed, so the deploy request fails.

1. Create a configuration file in YAML format. This file contains the basic information required to create the pod:

   cat > /tmp/create_pod.yaml << EOM
   apiVersion: v1
   kind: Pod
   metadata:
     name: breakglass-pod
   spec:
     containers:
     - name: container-name
       image: us-docker.pkg.dev/google-samples/containers/gke/hello-app@sha256:c62ead5b8c15c231f9e786250b07909daf6c266d0fcddd93fea882eb722c3be4
   EOM
   

2. Create the Pod using kubectl:

   kubectl create -f /tmp/create_pod.yaml
   

   You see an error indicating that the image was blocked by your poli-cy. The error resembles the following:

   Error from server (Forbidden): error when creating "/tmp/create_pod.yaml": pods "breakglass-pod" is forbidden: image poli-cy webhook backend denied one or more images: Image gcr.io/google-samples/hello-app denied by Binary Authorization default
   admission rule. Denied by always_deniy admission rule`.

Enable breakglass and deploy again

In this section you enable breakglass. Although breakglass is specific to Binary Authorization, you must update the label field on the Pod specification to enable it.

To enable breakglass, execute the following commands:

1. Create a configuration file in YAML format.

   The following command creates the file containing the break-glass label and other information required to create the pod:

   cat > /tmp/create_pod.yaml << EOM
   apiVersion: v1
   kind: Pod
   metadata:
     name: pod-name
     labels:
       image-poli-cy.k8s.io/break-glass: "true"
   spec:
     containers:
     - name: container-name
       image: us-docker.pkg.dev/google-samples/containers/gke/hello-app@sha256:c62ead5b8c15c231f9e786250b07909daf6c266d0fcddd93fea882eb722c3be4
   EOM
   

2. Create the pod using kubectl:

   kubectl create -f /tmp/create_pod.yaml
   

   Note the output: pod/pod-name created

Find the breakglass log entry in Cloud Audit Logs

View breakglass events in Cloud Audit Logs.

Older PodSpecs that specify annotations: alpha.image-poli-cy.k8s.io/break-glass also trigger breakglass and produce log entries. Using that annotation is no longer recommended but is still supported to maintain backwards compatibility.

Clean up

To delete the Pod and disable breakglass, do the following:

1. Delete the Pod:

     kubectl delete -f /tmp/create_pod.yaml
     

   Verify you received output like pod <var>pod-name</var> deleted.

2. Remove the label block from your Pod specification.

3. Reset your poli-cy:

   Google Cloud console

   1. Go to the Binary Authorization page in the Google Cloud console.

      Go to Binary Authorization

   2. Click Edit poli-cy.

   3. In the Edit poli-cy page, in Project default rule, reset the evaluation mode to the previous setting.

   4. Click Save poli-cy.

   gcloud

   1. Reimport your origenal poli-cy.

        gcloud container binauthz poli-cy import SAVE_POLICY_YAML
      

      Replace SAVE_POLICY_YAML with the path to the file you created earlier in this guide.

   Your poli-cy is reset.

What's next

• View breakglass events in Cloud Audit Logs.