GSP493

Overview

This lab covers the usage and debugging of role-based access control (RBAC) in a Kubernetes Engine cluster.

While RBAC resource definitions are standard across all Kubernetes platforms, their interaction with underlying authentication and authorization providers needs to be understood when building on any cloud provider.

RBAC is a powerful security mechanism that provides great flexibility in how you restrict operations within a cluster. This lab will cover two use cases for RBAC:

1. Assigning different permissions to user personas, namely owners and auditors.
2. Granting limited API access to an application running within your cluster.

Since RBAC's flexibility can occasionally result in complex rules, common steps for troubleshooting RBAC are included as part of scenario 2.

Architecture

This lab focuses on the use of RBAC within a Kubernetes Engine cluster. It demonstrates how varying levels of cluster privilege can be granted to different user personas. You will provision two service accounts to represent user personas and three namespaces: dev, test, and prod. The "owner" persona will have read-write access to all three namespaces, while the "auditor" persona will have read-only access and be restricted to the dev namespace.

This lab was created by GKE Helmsman engineers to help you grasp a better understanding of Using role-based access controls in GKE. You can view this demo on Github. We encourage any and all to contribute to our assets!

Setup and requirements

Before you click the Start Lab button

Read these instructions. Labs are timed and you cannot pause them. The timer, which starts when you click Start Lab, shows how long Google Cloud resources will be made available to you.

This hands-on lab lets you do the lab activities yourself in a real cloud environment, not in a simulation or demo environment. It does so by giving you new, temporary credentials that you use to sign in and access Google Cloud for the duration of the lab.

To complete this lab, you need:

• Access to a standard internet browser (Chrome browser recommended).

Note: Use an Incognito or private browser window to run this lab. This prevents any conflicts between your personal account and the Student account, which may cause extra charges incurred to your personal account.

• Time to complete the lab---remember, once you start, you cannot pause a lab.

Note: If you already have your own personal Google Cloud account or project, do not use it for this lab to avoid extra charges to your account.

How to start your lab and sign in to the Google Cloud console

1. Click the Start Lab button. If you need to pay for the lab, a pop-up opens for you to select your payment method. On the left is the Lab Details panel with the following:

   • The Open Google Cloud console button
   • Time remaining
   • The temporary credentials that you must use for this lab
   • Other information, if needed, to step through this lab

2. Click Open Google Cloud console (or right-click and select Open Link in Incognito Window if you are running the Chrome browser).

   The lab spins up resources, and then opens another tab that shows the Sign in page.

   Tip: Arrange the tabs in separate windows, side-by-side.

   Note: If you see the Choose an account dialog, click Use Another Account.

3. If necessary, copy the Username below and paste it into the Sign in dialog.

   {{{user_0.username | "Username"}}}

   You can also find the Username in the Lab Details panel.

4. Click Next.

5. Copy the Password below and paste it into the Welcome dialog.

   {{{user_0.password | "Password"}}}

   You can also find the Password in the Lab Details panel.

6. Click Next.

   Important: You must use the credentials the lab provides you. Do not use your Google Cloud account credentials. Note: Using your own Google Cloud account for this lab may incur extra charges.

7. Click through the subsequent pages:

   • Accept the terms and conditions.
   • Do not add recovery options or two-factor authentication (because this is a temporary account).
   • Do not sign up for free trials.

After a few moments, the Google Cloud console opens in this tab.

Note: To view a menu with a list of Google Cloud products and services, click the Navigation menu at the top-left.

Activate Cloud Shell

Cloud Shell is a virtual machine that is loaded with development tools. It offers a persistent 5GB home directory and runs on the Google Cloud. Cloud Shell provides command-line access to your Google Cloud resources.

1. Click Activate Cloud Shell at the top of the Google Cloud console.

When you are connected, you are already authenticated, and the project is set to your Project_ID, . The output contains a line that declares the Project_ID for this session:

Your Cloud Platform project in this session is set to {{{project_0.project_id | "PROJECT_ID"}}}

gcloud is the command-line tool for Google Cloud. It comes pre-installed on Cloud Shell and supports tab-completion.

2. (Optional) You can list the active account name with this command:

gcloud auth list

3. Click Authorize.

Output:

ACTIVE: * ACCOUNT: {{{user_0.username | "ACCOUNT"}}} To set the active account, run: $ gcloud config set account `ACCOUNT`

4. (Optional) You can list the project ID with this command:

gcloud config list project

Output:

[core] project = {{{project_0.project_id | "PROJECT_ID"}}} Note: For full documentation of gcloud, in Google Cloud, refer to the gcloud CLI overview guide.

Set your region and zone

Certain Compute Engine resources live in regions and zones. A region is a specific geographical location where you can run your resources. Each region has one or more zones.

Learn more about regions and zones and see a complete list in Regions & Zones documentation.

Run the following to set a region and zone for your lab (you can use the region/zone that's best for you):

gcloud config set compute/region {{{project_0.default_region|REGION}}} gcloud config set compute/zone {{{project_0.default_zone|ZONE}}}

Task 1. Clone demo

1. Download the resources needed for this lab by running:

gsutil cp gs://spls/gsp493/gke-rbac-demo.tar . tar -xvf gke-rbac-demo.tar

2. Change into the extracted directory:

cd gke-rbac-demo

Provisioning the Kubernetes Engine cluster

Next, apply the Terraform configuration.

1. From within the project root, use make to apply the Terraform configuration:

make create

The setup of this demo takes up to 10-15 minutes. If there is no error the best thing to do is keep waiting. The execution of make create should not be interrupted.

2. While the resources are building, once you see a google_compute_instance get created, you can check on the progress in the Console by going to Compute Engine > VM instances. Use the Refresh button on the VM instances page to view the most up to date information.

Once complete, Terraform outputs a message indicating successful creation of the cluster.

3. Confirm the cluster was created successfully in the Console. Go to Navigation menu > Kubernetes Engine > Clusters and click on the cluster that was created. Ensure that Legacy Authorization is disabled for the new cluster.

Click Check my progress to verify the objective. Provisioning the Kubernetes Engine Cluster

Task 2. Scenario 1: Assigning permissions by user persona

IAM - role

A role named kube-api-ro-xxxxxxxx (where xxxxxxxx is a random string) has been created with the permissions below as part of the Terraform configuration in iam.tf. These permissions are the minimum required for any user that requires access to the Kubernetes API.

• container.apiServices.get
• container.apiServices.list
• container.clusters.get
• container.clusters.getCredentials

Simulating users

Three service accounts have been created to act as Test Users:

• admin: has admin permissions over the cluster and all resources
• owner: has read-write permissions over common cluster resources
• auditor: has read-only permissions within the dev namespace only

1. Run the following:

gcloud iam service-accounts list

Three test hosts have been provisioned by the Terraform script. Each node has kubectl and gcloud installed and configured to simulate a different user persona.

• gke-tutorial-admin: kubectl and gcloud are authenticated as a cluster administrator.
• gke-tutorial-owner: simulates the owner account
• gke-tutorial-auditor: simulates the auditor account

2. Run the following:

gcloud compute instances list

Output:

NAME ZONE MACHINE_TYPE PREEMPTIBLE INTERNAL_IP EXTERNAL_IP STATUS rbac-demo-cluster-default-pool-a9cd3468-4vpc {{{project_0.default_zone|ZONE}}} n1-standard-1 10.0.96.5 RUNNING rbac-demo-cluster-default-pool-a9cd3468-b47f {{{project_0.default_zone|ZONE}}} n1-standard-1 10.0.96.6 RUNNING rbac-demo-cluster-default-pool-a9cd3468-rt5p {{{project_0.default_zone|ZONE}}} n1-standard-1 10.0.96.7 RUNNING gke-tutorial-auditor {{{project_0.default_zone|ZONE}}} f1-micro 10.0.96.4 35.224.148.28 RUNNING gke-tutorial-admin {{{project_0.default_zone|ZONE}}} f1-micro 10.0.96.3 35.226.237.142 RUNNING gke-tutorial-owner {{{project_0.default_zone|pZONE}}} f1-micro 10.0.96.2 35.194.58.130 RUNNING

Creating the RBAC rules

Create the Namespaces, Roles, and RoleBindings by logging into the admin instance and applying the rbac.yaml manifest.

1. SSH to the admin:

gcloud compute ssh gke-tutorial-admin Note: Ignore the error which relates to gcp auth plugin.

Existing versions of kubectl and custom Kubernetes clients contain provider-specific code to manage authentication between the client and Google Kubernetes Engine. Starting with v1.26, this code will no longer be included as part of the OSS kubectl. GKE users will need to download and use a separate authentication plugin to generate GKE-specific tokens. This new binary, gke-gcloud-auth-plugin, uses the Kubernetes Client-go Credential Plugin mechanism to extend kubectl’s authentication to support GKE. For more information, you can check out the following documentation.

To have kubectl use the new binary plugin for authentication instead of using the default provider-specific code, use the following steps.

2. Once connected, run the following command to install the gke-gcloud-auth-plugin on the VM.

sudo apt-get install google-cloud-sdk-gke-gcloud-auth-plugin

3. Set export USE_GKE_GCLOUD_AUTH_PLUGIN=True in ~/.bashrc:

echo "export USE_GKE_GCLOUD_AUTH_PLUGIN=True" >> ~/.bashrc

4. Run the following command:

source ~/.bashrc

5. Run the following command to force the config for this cluster to be updated to the Client-go Credential Plugin configuration.

gcloud container clusters get-credentials rbac-demo-cluster --zone {{{project_0.default_zone|ZONE}}}

On success, you should see this message pop up:

Kubeconfig entry generated for dev-cluster.

The newly-created cluster will now be available for the standard kubectl commands on the bastion.

6. Create the namespaces, roles, and bindings:

kubectl apply -f ./manifests/rbac.yaml

Output:

namespace/dev created namespace/prod created namespace/test created role.rbac.authorization.k8s.io/dev-ro created clusterrole.rbac.authorization.k8s.io/all-rw created clusterrolebinding.rbac.authorization.k8s.io/owner-binding created rolebinding.rbac.authorization.k8s.io/auditor-binding created

Click Check my progress to verify the objective. Creating the RBAC rules

Managing resources as the owner

1. Open a new Cloud Shell terminal by clicking the + at the top of the terminal window.

You will now SSH into the owner instance and create a simple deployment in each namespace.

2. SSH to the "owner" instance:

gcloud compute ssh gke-tutorial-owner Note: Ignore the error which relates to gcp auth plugin.

3. When prompted about the zone, enter n, so the default zone is used.

4. Install gke-gcloud-auth-plugin:

sudo apt-get install google-cloud-sdk-gke-gcloud-auth-plugin echo "export USE_GKE_GCLOUD_AUTH_PLUGIN=True" >> ~/.bashrc source ~/.bashrc gcloud container clusters get-credentials rbac-demo-cluster --zone {{{project_0.default_zone|ZONE}}}

5. Create a server in each namespace, first dev:

kubectl create -n dev -f ./manifests/hello-server.yaml

Output:

service/hello-server created deployment.apps/hello-server created

6. And then prod:

kubectl create -n prod -f ./manifests/hello-server.yaml

Output:

service/hello-server created deployment.apps/hello-server created

7. Then test:

kubectl create -n test -f ./manifests/hello-server.yaml

Output:

service/hello-server created deployment.apps/hello-server created

Click Check my progress to verify the objective. Create a server in each namespace

As the owner, you will also be able to view all pods.

• On the "owner" instance list all hello-server pods in all namespaces by running:

kubectl get pods -l app=hello-server --all-namespaces

Output:

NAMESPACE NAME READY STATUS RESTARTS AGE dev hello-server-6c6fd59cc9-h6zg9 1/1 Running 0 6m prod hello-server-6c6fd59cc9-mw2zt 1/1 Running 0 44s test hello-server-6c6fd59cc9-sm6bs 1/1 Running 0 39s

Viewing resources as the auditor

Now you will open a new terminal, SSH into the auditor instance, and try to view all namespaces.

1. Open a new Cloud Shell terminal by clicking the + at the top of the terminal window.

2. SSH to the "auditor" instance:

gcloud compute ssh gke-tutorial-auditor Note: Ignore the error which relates to gcp auth plugin.

3. When prompted about the zone, enter n, so the default zone is used.

4. Install gke-gcloud-auth-plugin:

sudo apt-get install google-cloud-sdk-gke-gcloud-auth-plugin echo "export USE_GKE_GCLOUD_AUTH_PLUGIN=True" >> ~/.bashrc source ~/.bashrc gcloud container clusters get-credentials rbac-demo-cluster --zone {{{project_0.default_zone|ZONE}}}

5. On the "auditor" instance, list all hello-server pods in all namespaces with the following:

kubectl get pods -l app=hello-server --all-namespaces

You should see an error like the following:

Error from server (Forbidden): pods is forbidden: User "gke-tutorial-auditor@myproject.iam.gserviceaccount.com" cannot list pods at the cluster scope: Required "container.pods.list" permission

The error indicates that you don't have sufficient permissions. The auditor role is restricted to viewing only the resources in the dev namespace, so you'll need to specify the namespace when viewing resources.

Now attempt to view pods in the dev namespace.

6. On the "auditor" instance run the following:

kubectl get pods -l app=hello-server --namespace=dev

Output:

NAME READY STATUS RESTARTS AGE hello-server-6c6fd59cc9-h6zg9 1/1 Running 0 13m

7. Try to view pods in the test namespace:

kubectl get pods -l app=hello-server --namespace=test

Output:

Error from server (Forbidden): pods is forbidden: User "gke-tutorial-auditor@myproject.iam.gserviceaccount.com" cannot list pods in the namespace "test": Required "container.pods.list" permission.

8. Attempt to view pods in the prod namespace:

kubectl get pods -l app=hello-server --namespace=prod

Output:

Error from server (Forbidden): pods is forbidden: User "gke-tutorial-auditor@myproject.iam.gserviceaccount.com" cannot list pods in the namespace "prod": Required "container.pods.list" permission.

Finally, verify that the auditor has read-only access by trying to create and delete a deployment in the dev namespace.

9. On the "auditor" instance attempt to create a deployment:

kubectl create -n dev -f manifests/hello-server.yaml

Output:

Error from server (Forbidden): error when creating "manifests/hello-server.yaml": services is forbidden: User "gke-tutorial-auditor@myproject.iam.gserviceaccount.com" cannot create services in the namespace "dev": Required "container.services.create" permission. Error from server (Forbidden): error when creating "manifests/hello-server.yaml": deployments.extensions is forbidden: User "gke-tutorial-auditor@myproject.iam.gserviceaccount.com" cannot create deployments.extensions in the namespace "dev": Required "container.deployments.create" permission.

10. On the "auditor" instance, attempt to delete the deployment:

kubectl delete deployment -n dev -l app=hello-server

Output:

Error from server (Forbidden): deployments.extensions "hello-server" is forbidden: User "gke-tutorial-auditor@myproject.iam.gserviceaccount.com" cannot update deployments.extensions in the namespace "dev": Required "container.deployments.update" permission.

Task 3. Scenario 2: Assigning API permissions to a cluster application

In this scenario you'll go through the process of deploying an application that requires access to the Kubernetes API as well as configure RBAC rules while troubleshooting some common use cases.

Deploying the sample application

The sample application will run as a single pod that periodically retrieves all pods in the default namespace from the API server and then applies a timestamp label to each one.

1. From the admin instance (this should be your first Cloud Shell tab), deploy the pod-labeler application. This will also deploy a Role, ServiceAccount, and RoleBinding for the pod:

kubectl apply -f manifests/pod-labeler.yaml

Output:

role.rbac.authorization.k8s.io/pod-labeler created serviceaccount/pod-labeler created rolebinding.rbac.authorization.k8s.io/pod-labeler created deployment.apps/pod-labeler created

Click Check my progress to verify the objective. Deploying the sample application

Diagnosing an RBAC misconfiguration

Now check the status of the pod. Once the container has finished creating, you'll see it error out. Investigate the error by inspecting the pods' events and logs.

1. On the admin instance check the pod status:

kubectl get pods -l app=pod-labeler

Output:

NAME READY STATUS RESTARTS AGE pod-labeler-6d9757c488-tk6sp 0/1 Error 1 1m

2. On the admin instance, view the pod event stream by running:

kubectl describe pod -l app=pod-labeler | tail -n 20

You should see:

Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled 7m35s default-scheduler Successfully assigned default/pod-labeler-5b4bd6cf9-w66jd to gke-rbac-demo-cluster-default-pool-3d348201-x0pk Normal Pulling 7m34s kubelet, gke-rbac-demo-cluster-default-pool-3d348201-x0pk pulling image "gcr.io/pso-examples/pod-labeler:0.1.5" Normal Pulled 6m56s kubelet, gke-rbac-demo-cluster-default-pool-3d348201-x0pk Successfully pulled image "gcr.io/pso-examples/pod-labeler:0.1.5" Normal Created 5m29s (x5 over 6m56s) kubelet, gke-rbac-demo-cluster-default-pool-3d348201-x0pk Created container Normal Pulled 5m29s (x4 over 6m54s) kubelet, gke-rbac-demo-cluster-default-pool-3d348201-x0pk Container image "gcr.io/pso-examples/pod-labeler:0.1.5" already present on machine Normal Started 5m28s (x5 over 6m56s) kubelet, gke-rbac-demo-cluster-default-pool-3d348201-x0pk Started container Warning BackOff 2m25s (x23 over 6m52s) kubelet, gke-rbac-demo-cluster-default-pool-3d348201-x0pk Back-off restarting failed container

3. On the admin instance, run the following to check the pod's logs:

kubectl logs -l app=pod-labeler

Output:

Attempting to list pods Traceback (most recent call last): File "label_pods.py", line 13, in ret = v1.list_namespaced_pod("default",watch=False) File "build/bdist.linux-x86_64/egg/kubernetes/client/apis/core_v1_api.py", line 12310, in list_namespaced_pod File "build/bdist.linux-x86_64/egg/kubernetes/client/apis/core_v1_api.py", line 12413, in list_namespaced_pod_with_http_info File "build/bdist.linux-x86_64/egg/kubernetes/client/api_client.py", line 321, in call_api File "build/bdist.linux-x86_64/egg/kubernetes/client/api_client.py", line 155, in __call_api File "build/bdist.linux-x86_64/egg/kubernetes/client/api_client.py", line 342, in request File "build/bdist.linux-x86_64/egg/kubernetes/client/rest.py", line 231, in GET File "build/bdist.linux-x86_64/egg/kubernetes/client/rest.py", line 222, in request kubernetes.client.rest.ApiException: (403) Reason: Forbidden HTTP response headers: HTTPHeaderDict({'Date': 'Fri, 25 May 2018 15:33:15 GMT', 'Audit-Id': 'ae2a0d7c-2ab0-4f1f-bd0f-24107d3c144e', 'Content-Length': '307', 'Content-Type': 'application/json', 'X-Content-Type-Options': 'nosniff'}) HTTP response body: {"kind":"Status","apiVersion":"v1","metadata":{},"status":"Failure","message":"pods is forbidden: User \"system:serviceaccount:default:default\" cannot list pods in the namespace \"default\": Unknown user \"system:serviceaccount:default:default\"","reason":"Forbidden","details":{"kind":"pods"},"code":403}

Based on this error, you can see a permissions error when trying to list pods via the API.

4. The next step is to confirm you are using the correct ServiceAccount.

Fixing the serviceAccountName

By inspecting the pod's configuration, you can see it is using the default ServiceAccount rather than the custom Service Account.

1. On the admin instance, run:

kubectl get pod -oyaml -l app=pod-labeler

Output:

restartPolicy: Always schedulerName: default-scheduler securityContext: fsGroup: 9999 runAsGroup: 9999 runAsUser: 9999 serviceAccount: default

The pod-labeler-fix-1.yaml file contains the fix in the deployment's template spec:

# Fix 1, set the serviceAccount so RBAC rules apply serviceAccount: pod-labeler

Next you'll apply the fix and view the resulting change.

2. On the admin instance, apply the fix 1 by running:

kubectl apply -f manifests/pod-labeler-fix-1.yaml

Output:

role.rbac.authorization.k8s.io/pod-labeler unchanged serviceaccount/pod-labeler unchanged rolebinding.rbac.authorization.k8s.io/pod-labeler unchanged deployment.apps/pod-labeler configured

3. View the change in the deployment configuration:

kubectl get deployment pod-labeler -oyaml

Changes in the output:

... restartPolicy: Always schedulerName: default-scheduler securityContext: {} serviceAccount: pod-labeler ...

Click Check my progress to verify the objective. Fixing the service account name

Diagnosing insufficient privileges

Once again, check the status of your pod and you'll notice it is still erring out, but with a different message this time.

1. On the admin instance check the status of your pod:

kubectl get pods -l app=pod-labeler

Output:

NAME READY STATUS RESTARTS AGE pod-labeler-c7b4fd44d-mr8qh 0/1 CrashLoopBackOff 3 1m

You may need to run the previous command again to see this output.

2. On the admin instance, check the pod's logs:

kubectl logs -l app=pod-labeler

Output:

File "/usr/local/lib/python3.8/site-packages/kubernetes/client/rest.py", line 292, in PATCH return self.request("PATCH", url, File "/usr/local/lib/python3.8/site-packages/kubernetes/client/rest.py", line 231, in request raise ApiException(http_resp=r) kubernetes.client.rest.ApiException: (403) Reason: Forbidden HTTP response headers: HTTPHeaderDict({'Audit-Id': 'f6c67c34-171f-42f3-b1c9-833e00cedd5e', 'Content-Type': 'application/json', 'X-Content-Type-Options': 'nosniff', 'Date': 'Mon, 23 Mar 2020 16:35:18 GMT', 'Content-Length': '358'}) HTTP response body: {"kind":"Status","apiVersion":"v1","metadata":{},"status":"Failure","message":"pods \"pod-labeler-659c8c99d5-t96pw\" is forbidden: User \"system:serviceaccount:default:pod-labeler\" cannot patch resource \"pods\" in API group \"\" in the namespace \"default\"","reason":"Forbidden","details":{"name":"pod-labeler-659c8c99d5-t96pw","kind":"pods"},"code":403}

Since this is failing on a PATCH operation, you can also see the error in Stackdriver. This is useful if the application logs are not sufficiently verbose.

3. In the Console, select Navigation menu, and in the Operations section, click on Logging.

4. In the Query builder dialog box, paste the following code and click Run Query:

protoPayload.methodName="io.k8s.core.v1.pods.patch"

5. Click on a down arrow next to a log record and explore the details.

Identifying the application's role and permissions

Use the ClusterRoleBinding to find the ServiceAccount's role and permissions.

1. On the admin instance, inspect the rolebinding definition:

kubectl get rolebinding pod-labeler -oyaml

Output:

apiVersion: rbac.authorization.k8s.io/v1 kind: RoleBinding metadata: annotations: kubectl.kubernetes.io/last-applied-configuration: | {"apiVersion":"rbac.authorization.k8s.io/v1","kind":"RoleBinding","metadata":{"annotations":{},"name":"pod-labeler","namespace":"default"},"roleRef":{"apiGroup":"rbac.authorization.k8s.io","kind":"Role","name":"pod-labeler"},"subjects":[{"kind":"ServiceAccount","name":"pod-labeler"}]} creationTimestamp: "2020-03-23T16:29:05Z" name: pod-labeler namespace: default resourceVersion: "2886" selfLink: /apis/rbac.authorization.k8s.io/v1/namespaces/default/rolebindings/pod-labeler uid: 0e4d5be7-d986-40d0-af1d-a660f9aa4336 roleRef: apiGroup: rbac.authorization.k8s.io kind: Role name: pod-labeler subjects: - kind: ServiceAccount name: pod-labeler

The RoleBinding shows you need to inspect the pod-labeler role in the default namespace. Here you can see the role is only granted permission to list pods.

2. On the admin instance, inspect the pod-labeler role definition:

kubectl get role pod-labeler -oyaml

Output:

apiVersion: rbac.authorization.k8s.io/v1 kind: Role metadata: annotations: kubectl.kubernetes.io/last-applied-configuration: | {"apiVersion":"rbac.authorization.k8s.io/v1","kind":"Role","metadata":{"annotations":{},"name":"pod-labeler","namespace":"default"},"rules":[{"apiGroups":[""],"resources":["pods"],"verbs":["list"]}]} creationTimestamp: "2020-03-23T16:29:05Z" name: pod-labeler namespace: default resourceVersion: "2883" selfLink: /apis/rbac.authorization.k8s.io/v1/namespaces/default/roles/pod-labeler uid: c8191869-c7de-42c6-98fc-79a91d9b02a1 rules: - apiGroups: - "" resources: - pods verbs: - list

Since the application requires PATCH permissions, you can add it to the "verbs" list of the role, which you will do now.

The pod-labeler-fix-2.yaml file contains the fix in it's rules/verbs section:

rules: - apiGroups: [""] # "" refers to the core API group resources: ["pods"] verbs: ["list","patch"] # Fix 2: adding permission to patch (update) pods

Apply the fix and view the resulting configuration.

3. On the admin instance, apply fix-2:

kubectl apply -f manifests/pod-labeler-fix-2.yaml

Output:

role.rbac.authorization.k8s.io/pod-labeler configured serviceaccount/pod-labeler unchanged rolebinding.rbac.authorization.k8s.io/pod-labeler unchanged deployment.apps/pod-labeler unchanged

Click Check my progress to verify the objective. Identifying the application's role and permissions

4. On the admin instance, view the resulting change:

kubectl get role pod-labeler -oyaml

Output:

apiVersion: rbac.authorization.k8s.io/v1 kind: Role metadata: annotations: kubectl.kubernetes.io/last-applied-configuration: | {"apiVersion":"rbac.authorization.k8s.io/v1","kind":"Role","metadata":{"annotations":{},"name":"pod-labeler","namespace":"default"},"rules":[{"apiGroups":[""],"resources":["pods"],"verbs":["list","patch"]}]} creationTimestamp: "2020-03-23T16:29:05Z" name: pod-labeler namespace: default resourceVersion: "8802" selfLink: /apis/rbac.authorization.k8s.io/v1/namespaces/default/roles/pod-labeler uid: c8191869-c7de-42c6-98fc-79a91d9b02a1 rules: - apiGroups: - "" resources: - pods verbs: - list - patch

Because the pod-labeler may be in a back-off loop, the quickest way to test the fix is to kill the existing pod and let a new one take its place.

5. On the admin instance, run the following to kill the existing pod and let the deployment controller replace it:

kubectl delete pod -l app=pod-labeler

Output:

pod "pod-labeler-659c8c99d5-t96pw" deleted

Verifying successful configuration

Finally, verify the new pod-labeler is running and check that the "updated" label has been applied.

1. On the admin instance, list all pods and show their labels:

kubectl get pods --show-labels

Output:

NAME READY STATUS RESTARTS NAME READY STATUS RESTARTS AGE LABELS pod-labeler-659c8c99d5-5qsmw 1/1 Running 0 31s app=pod-labeler,pod-template-hash=659c8c99d5,updated=1584982487.6428008

2. View the pod's logs to verify there are no longer any errors:

kubectl logs -l app=pod-labeler

Output:

Attempting to list pods labeling pod pod-labeler-659c8c99d5-5qsmw labeling pod pod-labeler-659c8c99d5-t96pw ...

Key take-aways

• Container and API server logs will be your best source of clues for diagnosing RBAC issues.
• Use RoleBindings or ClusterRoleBindings to determine which role is specifying the permissions for a pod.
• API server logs can be found in Stackdriver under the Kubernetes resource.
• Not all API calls will be logged to Stackdriver. Frequent, or verbose payloads are omitted by the Kubernetes' audit policy used in Kubernetes Engine. The exact policy will vary by Kubernetes version, but can be found in the open source codebase.

Task 4. Teardown

When you are finished, and you are ready to clean up the resources that were created, run the following command to remove all resources:

1. Log out of the bastion host by typing exit.

2. Run the following to destroy the environment:

make teardown

Output:

...snip... google_service_account.auditor: Destruction complete after 0s module.network.google_compute_subnetwork.cluster-subnet: Still destroying... (ID: us-east1/kube-net-subnet, 10s elapsed) module.network.google_compute_subnetwork.cluster-subnet: Still destroying... (ID: us-east1/kube-net-subnet, 20s elapsed) module.network.google_compute_subnetwork.cluster-subnet: Destruction complete after 26s module.network.google_compute_network.gke-network: Destroying... (ID: kube-net) module.network.google_compute_network.gke-network: Still destroying... (ID: kube-net, 10s elapsed) module.network.google_compute_network.gke-network: Still destroying... (ID: kube-net, 20s elapsed) module.network.google_compute_network.gke-network: Destruction complete after 25s Destroy complete! Resources: 14 destroyed.

Click Check my progress to verify the objective. Teardown

Task 5. Troubleshooting in your own environment

The install script fails with a Permission denied when running Terraform

The credentials that Terraform is using do not provide the necessary permissions to create resources in the selected projects. Ensure that the account listed in gcloud config list has necessary permissions to create resources. If it does, regenerate the application default credentials using gcloud auth application-default login.

Invalid fingerprint error during Terraform operations

Terraform occasionally complains about an invalid fingerprint, when updating certain resources. Re-run the command if you get an error with the message: Error: Error applying plan and then lists these errors:

• module.network.google_compute_subnetwork.cluster-subnet: 1 error(s) occurred
• google.compute_subnetwork.cluster-subnet: Error updating subnetwork /kube-net-subnet: googleapi: Error412: Invalid fingerprint, conditionNotMet

Congratulations!

You've explored role-based access (RBAC) control by assigning different permissions to user personas and granting limited API access to an application running in your cluster.

Next steps / Learn more

• Configure role-based access control
• Create IAM policies
• Kubernetes Service Account Authentication
• Terraform Documentation

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Manual Last Updated November 04, 2024

Lab Last Tested November 04, 2024

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