Applying backend-config annotation on existing ingress service has no effect

[mikouaj]

Issue

Applying cloud.google.com/backend-config annotation on an existing service, that is associated with an existing Ingress, makes no changes on underlying backend service.

Use cases

• configuring CloudArmor on GKE provided default backend service, that is default-http-backend in kube-system name space
• configuring CloudArmor, IAP or other services on any existing service that is part of an Ingress but had no corresponding BackendConfig object

Steps to reproduce

1. Create Service that matches some existing deployment
2. Create Ingress associated with the service created above
3. Wait until ingress is created and in sync
4. Create BackendConfig with Cloud Armor policy configuration (any other configuration will apply as well)
5. Annotate service with cloud.google.com/backend-config annotation pointing to BackendConfig created in previous step

Expected Behavior

Cloud Armor policy is configured on a corresponding backend service

Actual Behavior

Nothing happens

GKE version

1.19.10-gke.1600

[boredabdel]

@bowei any idea about this?

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/lifecycle stale

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/lifecycle rotten

[jsravn]

Alternatively, we should be able to disable the default backend. Very few people want or are aware that ingress-gce forwards all unmatched external traffic to a pod in kube-system. This is undesirable from a security standpoint.

[bowei]

/remove-lifecycle rotten

[bowei]

Default backend can be removed when all of the products support a 404 response instead of requiring a Pod to 404. -- however, that seems to not be related to the issue title?

[bowei]

We will take a look at this bug in the triage.

[freehan]

Does this only impact CloudArmor config or any other config in BackendConfig?

We had a problem with CloudArmor in that version you provided and it is since fixed.

[raphaelauv]

@mikouaj I have the same problem

GKE : 1.21.5-gke.1302

[edclement]

Count me in on this problem as well. We can't seem to get a BackendConfig which has a securityPolicy attached to the Ingress (docs). So instead of relying on the BackendConfig we have to manually attach the policy.

We use GKE Autopilot if that matters.

{
  "Major": "1",
  "Minor": "20+",
  "GitVersion": "v1.20.10-gke.1600",
  "GitCommit": "ef8e9f64449d73f9824ff5838cea80e21ec6c127",
  "GitTreeState": "clean",
  "BuildDate": "2021-09-06T09:24:20Z",
  "GoVersion": "go1.15.15b5",
  "Compiler": "gc",
  "Platform": "linux/amd64"
}

[k8s-triage-robot]

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/lifecycle stale

[bowei]

/assign @spencerhance

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[spencerhance]

Ack

[swetharepakula]

/kind bug

[msuterski]

We are running to a similar issue. We're required to attach security policies to all exposed backends, including the ones created via/for default http backend.

We're currently considering various "creative" solutions, but it would be a lot easier if it was fixed on the GCE Ingress level.

Thanks for looking into it.

[spencerhance]

Hi Folks, I attempted to repro this locally by adding a security policy and backendconfig to a service after the LB was provisioned - but I was unable to. If you share your redacted YAMLs or email your cluster info to the email on my profile I can take another look.

[msuterski]

@spencerhance thanks for your comment/verification. It does seem to work for default backends when they are attached to healthy Ingresses!

For future reference the steps to have the policies attached to default backends.

1. Create a security policy for the default http backend in the gcp project

   gcloud compute security-policies create default-http-backend

2. Attach rule(s) to your security policy. (in this case we're attaching policy to deny all access by default and return 404)

   gcloud compute security-policies rules update 2147483647 --security-policy default-http-backend --action "deny-404"

3. Create BackendConfig resource in the kube-system namespace

   # backend.yaml
   ---
   apiVersion: cloud.google.com/v1
   kind: BackendConfig
   metadata:
     name: default-http-backend
     labels:
       app.kubernetes.io/name: default-http-backend
   spec:
     timeoutSec: 40
     securityPolicy:
       name: default-http-backend

   kubectl apply -f backend.yaml -n kube-system

4. Patch the default backend service to attach the required annotation

   # annotation.yaml
   metadata:
     annotations:
       cloud.google.com/backend-config: |
         {"default":"default-http-backend"}

   kubectl patch service default-http-backend --patch-file annotation.yaml -n kube-system

just FYI, this process does not work for Ingresses which backends are in an unhealthy state

[spencerhance]

just FYI, this process does not work for Ingresses which backends are in an unhealthy state

@msuterski
Can you elaborate, are the Backends unhealthy or is the ingress have a configuration issue that prevents it from being fully synced?

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/lifecycle rotten

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/close

[k8s-ci-robot]

@k8s-triage-robot: Closing this issue.

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/close

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