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Linux Foundation CKS Practice Test - Questions Answers, Page 3
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Question 21
Create a Pod name Nginx-pod inside the namespace testing, Create a service for the Nginx-pod named nginx-svc, using the ingress of your choice, run the ingress on tls, secure port.
Explanation:
$ kubectl get ing -n <namespace-of-ingress-resource>
NAME HOSTS ADDRESS PORTS AGE cafe-ingress cafe.com 10.0.2.15 80 25s $ kubectl describe ing <ingress-resource-name> -n <namespace-of-ingress-resource> Name: cafe-ingress Namespace: default Address: 10.0.2.15 Default backend: default-http-backend:80 (172.17.0.5:8080) Rules:
Host Path Backends
---- ---- -------- cafe.com
/tea tea-svc:80 (<none>)
/coffee coffee-svc:80 (<none>)
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"networking.k8s.io/v1","kind":"Ingress","metadata":{"annotations":{},"name":"cafeingress"," namespace":"default","selfLink":"/apis/networking/v1/namespaces/default/ingresses/cafe -ingress"},"spec":{"rules":[{"host":"cafe.com","http":{"paths":[{"backend":{"serviceName":"teasvc"," servicePort":80},"path":"/tea"},{"backend":{"serviceName":"coffeesvc"," servicePort":80},"path":"/coffee"}]}}]},"status":{"loadBalancer":{"ingress":[{"ip":"169.48.142.11 0"}]}}} Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal CREATE 1m ingress-nginx-controller Ingress default/cafe-ingress Normal UPDATE 58s ingress-nginx-controller Ingress default/cafe-ingress $ kubectl get pods -n <namespace-of-ingress-controller> NAME READY STATUS RESTARTS AGE ingress-nginx-controller-67956bf89d-fv58j 1/1 Running 0 1m $ kubectl logs -n <namespace> ingress-nginx-controller-67956bf89d-fv58j ------------------------------------------------------------------------------- NGINX Ingress controller Release: 0.14.0 Build: git-734361d Repository: https://github.com/kubernetes/ingress-nginx -------------------------------------------------------------------------------
....
Question 22
Secrets stored in the etcd is not secure at rest, you can use the etcdctl command utility to find the secret value
for e.g:-
ETCDCTL_API=3 etcdctl get /registry/secrets/default/cks-secret --cacert="ca.crt" --cert="server.crt" --
key="server.key"
Output
Using the Encryption Configuration, Create the manifest, which secures the resource secrets using the provider AES-CBC and identity, to encrypt the secret-data at rest and ensure all secrets are encrypted with the new configuration.
Explanation:
ETCD secret encryption can be verified with the help of etcdctl command line utility.
ETCD secrets are stored at the path /registry/secrets/$namespace/$secret on the master node.
The below command can be used to verify if the particular ETCD secret is encrypted or not.
# ETCDCTL_API=3 etcdctl get /registry/secrets/default/secret1 [...] | hexdump -C
Question 23
Use the kubesec docker images to scan the given YAML manifest, edit and apply the advised changes,
and passed with a score of 4 points.
kubesec-test.yaml
apiVersion: v1
kind: Pod
metadata:
name: kubesec-demo
spec:
containers:
- name: kubesec-demo
image: gcr.io/google-samples/node-hello:1.0
securityContext:
readOnlyRootFilesystem: true
Hint: docker run -i kubesec/kubesec:512c5e0 scan /dev/stdin < kubesec-test.yaml
Explanation:
kubesec scan k8s-deployment.yaml
cat <<EOF > kubesec-test.yaml
apiVersion: v1
kind: Pod
metadata:
name: kubesec-demo
spec:
containers:
- name: kubesec-demo
image: gcr.io/google-samples/node-hello:1.0
securityContext:
readOnlyRootFilesystem: true
EOF
kubesec scan kubesec-test.yaml
docker run -i kubesec/kubesec:512c5e0 scan /dev/stdin < kubesec-test.yaml
kubesec http 8080 &
[1] 12345
{"severity":"info","timestamp":"2019-05-
12T11:58:34.662+0100","caller":"server/server.go:69","message":"Starting HTTP server on port
8080"}
curl -sSX POST --data-binary @test/asset/score-0-cap-sys-admin.yml http://localhost:8080/scan
[
{
"object": "Pod/security-context-demo.default",
"valid": true,
"message": "Failed with a score of -30 points",
"score": -30,
"scoring": {
"critical": [
{
"selector": "containers[] .securityContext .capabilities .add == SYS_ADMIN",
"reason": "CAP_SYS_ADMIN is the most privileged capability and should always be avoided"
},
{
"selector": "containers[] .securityContext .runAsNonRoot == true",
"reason": "Force the running image to run as a non-root user to ensure least privilege"
},
// ...
Question 24
Cluster: qa-cluster
Master node: master Worker node: worker1
You can switch the cluster/configuration context using the following command:
[desk@cli] $ kubectl config use-context qa-cluster
Task:
Create a NetworkPolicy named restricted-policy to restrict access to Pod product running in namespace dev.
Only allow the following Pods to connect to Pod products-service:
1. Pods in the namespace qa
2. Pods with label environment: stage, in any namespace
Explanation:
Reference: https://kubernetes.io/docs/concepts/services-networking/network-policies/
Question 25
Context
A container image scanner is set up on the cluster, but it's not yet fully integrated into the cluster s configuration. When complete, the container image scanner shall scan for and reject the use of vulnerable images.
Task
Given an incomplete configuration in directory /etc/kubernetes/epconfig and a functional container image scanner with HTTPS endpoint https://wakanda.local:8081 /image_policy :
1. Enable the necessary plugins to create an image policy
2. Validate the control configuration and change it to an implicit deny
3. Edit the configuration to point to the provided HTTPS endpoint correctlyFinally, test if the configuration is working by trying to deploy the vulnerable resource /root/KSSC00202/vulnerable-resource.yml.
Explanation:
Question 26
You must complete this task on the following cluster/nodes: Cluster: immutable-cluster
Master node: master1
Worker node: worker1
You can switch the cluster/configuration context using the following command:
[desk@cli] $ kubectl config use-context immutable-cluster
Context: It is best practice to design containers to be stateless and immutable.
Task:
Inspect Pods running in namespace prod and delete any Pod that is either not stateless or not immutable.
Use the following strict interpretation of stateless and immutable:
1. Pods being able to store data inside containers must be treated as not stateless.
Note: You don't have to worry whether data is actually stored inside containers or not already.
2. Pods being configured to be privileged in any way must be treated as potentially not stateless or not immutable.
Explanation:
Reference: https://kubernetes.io/docs/concepts/policy/pod-security-policy/
https://cloud.google.com/architecture/best-practices-for-operating-containers
Question 27
You can switch the cluster/configuration context using the following command:
[desk@cli] $ kubectl config use-context stage
Context:
A PodSecurityPolicy shall prevent the creation of privileged Pods in a specific namespace.
Task:
1. Create a new PodSecurityPolcy named deny-policy, which prevents the creation of privileged Pods.
2. Create a new ClusterRole name deny-access-role, which uses the newly created PodSecurityPolicy deny-policy.
3. Create a new ServiceAccount named psd-denial-sa in the existing namespace development.
Finally, create a new ClusterRoleBindind named restrict-access-bind, which binds the newly created ClusterRole deny-access-role to the newly created ServiceAccount psp-denial-sa
Explanation:
Create psp to disallow privileged container
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: deny-access-role
rules:
- apiGroups: ['policy']
resources: ['podsecuritypolicies']
verbs: ['use']
resourceNames:
- “deny-policy”
k create sa psp-denial-sa -n development
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: restrict-access-bing
roleRef:
kind: ClusterRole
name: deny-access-role
apiGroup: rbac.authorization.k8s.io
subjects:
- kind: ServiceAccount
name: psp-denial-sa
namespace: development
Explanation
master1 $ vim psp.yaml
apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
name: deny-policy
spec:
privileged: false # Don't allow privileged pods!
seLinux:
rule: RunAsAny
supplementalGroups:
rule: RunAsAny
runAsUser:
rule: RunAsAny
fsGroup:
rule: RunAsAny
volumes:
- '*'
master1 $ vim cr1.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: deny-access-role
rules:
- apiGroups: ['policy']
resources: ['podsecuritypolicies']
verbs: ['use']
resourceNames:
- “deny-policy”
master1 $ k create sa psp-denial-sa -n development
master1 $ vim cb1.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: restrict-access-bing
roleRef:
kind: ClusterRole
name: deny-access-role
apiGroup: rbac.authorization.k8s.io
subjects:
# Authorize specific service accounts:
- kind: ServiceAccount
name: psp-denial-sa
namespace: development
master1 $ k apply -f psp.yaml
master1 $ k apply -f cr1.yaml
master1 $ k apply -f cb1.yaml
Reference: https://kubernetes.io/docs/concepts/policy/pod-security-policy/
Question 28
Context:
Cluster: prod
Master node: master1
Worker node: worker1
You can switch the cluster/configuration context using the following command:
[desk@cli] $ kubectl config use-context prod
Task:
Analyse and edit the given Dockerfile (based on the ubuntu:18:04 image)
/home/cert_masters/Dockerfile fixing two instructions present in the file being prominent security/best-practice issues.
Analyse and edit the given manifest file
/home/cert_masters/mydeployment.yaml fixing two fields present in the file being prominent security/best-practice issues.
Note: Don't add or remove configuration settings; only modify the existing configuration settings, so that two configuration settings each are no longer security/best-practice concerns.
Should you need an unprivileged user for any of the tasks, use user nobody with user id 65535
Explanation:
1. For Dockerfile: Fix the image version & user name in Dockerfile
2. For mydeployment.yaml : Fix security contexts
[desk@cli] $ vim /home/cert_masters/Dockerfile
FROM ubuntu:latest # Remove this
FROM ubuntu:18.04 # Add this
USER root # Remove this
USER nobody # Add this
RUN apt get install -y lsof=4.72 wget=1.17.1 nginx=4.2
ENV ENVIRONMENT=testing
USER root # Remove this
USER nobody # Add this
CMD ["nginx -d"]
[desk@cli] $ vim /home/cert_masters/mydeployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
creationTimestamp: null
labels:
app: kafka
name: kafka
spec:
replicas: 1
selector:
matchLabels:
app: kafka
strategy: {}
template:
metadata:
creationTimestamp: null
labels:
app: kafka
spec:
containers:
- image: bitnami/kafka
name: kafka
volumeMounts:
- name: kafka-vol
mountPath: /var/lib/kafka
securityContext:
{"capabilities":{"add":["NET_ADMIN"],"drop":["all"]},"privileged":
True,"readOnlyRootFilesystem": False, "runAsUser": 65535} # Delete This
{"capabilities":{"add":["NET_ADMIN"],"drop":["all"]},"privileged":
False,"readOnlyRootFilesystem": True, "runAsUser": 65535} # Add This
resources: {}
volumes:
- name: kafka-vol
emptyDir: {}
status: {}
Pictorial View:
[desk@cli] $ vim /home/cert_masters/mydeployment.yaml
Reference: https://kubernetes.io/docs/concepts/policy/pod-security-policy/
Question 29
You can switch the cluster/configuration context using the following command:
[desk@cli] $ kubectl config use-context test-account
Task: Enable audit logs in the cluster.
To do so, enable the log backend, and ensure that:
1. logs are stored at /var/log/Kubernetes/logs.txt
2. log files are retained for 5 days
3. at maximum, a number of 10 old audit log files are retained
A basic policy is provided at /etc/Kubernetes/logpolicy/audit-policy.yaml. It only specifies what not to log.
Note: The base policy is located on the cluster's master node.
Edit and extend the basic policy to log:
1. Nodes changes at RequestResponse level
2. The request body of persistentvolumes changes in the namespace frontend
3. ConfigMap and Secret changes in all namespaces at the Metadata level Also, add a catch-all rule to log all other requests at the Metadata level Note: Don't forget to apply the modified policy.
Explanation:
$ vim /etc/kubernetes/log-policy/audit-policy.yaml
- level: RequestResponse
userGroups: ["system:nodes"]
- level: Request
resources:
- group: "" # core API group
resources: ["persistentvolumes"]
namespaces: ["frontend"]
- level: Metadata
resources:
- group: ""
resources: ["configmaps", "secrets"]
- level: Metadata
$ vim /etc/kubernetes/manifests/kube-apiserver.yaml
Add these
- --audit-policy-file=/etc/kubernetes/log-policy/audit-policy.yaml
- --audit-log-path=/var/log/kubernetes/logs.txt
- --audit-log-maxage=5
- --audit-log-maxbackup=10
Explanation
[desk@cli] $ ssh master1
[master1@cli] $ vim /etc/kubernetes/log-policy/audit-policy.yaml
apiVersion: audit.k8s.io/v1 # This is required.
kind: Policy
# Don't generate audit events for all requests in RequestReceived stage.
omitStages:
- "RequestReceived"
rules:
# Don't log watch requests by the "system:kube-proxy" on endpoints or services
- level: None
users: ["system:kube-proxy"]
verbs: ["watch"]
resources:
- group: "" # core API group
resources: ["endpoints", "services"]
# Don't log authenticated requests to certain non-resource URL paths.
- level: None
userGroups: ["system:authenticated"]
nonResourceURLs:
- "/api*" # Wildcard matching.
- "/version"
# Add your changes below
- level: RequestResponse
userGroups: ["system:nodes"] # Block for nodes
- level: Request
resources:
- group: "" # core API group
resources: ["persistentvolumes"] # Block for persistentvolumes
namespaces: ["frontend"] # Block for persistentvolumes of frontend ns
- level: Metadata
resources:
- group: "" # core API group
resources: ["configmaps", "secrets"] # Block for configmaps & secrets
- level: Metadata # Block for everything else
[master1@cli] $ vim /etc/kubernetes/manifests/kube-apiserver.yaml
apiVersion: v1
kind: Pod
metadata:
annotations:
kubeadm.kubernetes.io/kube-apiserver.advertise-address.endpoint: 10.0.0.5:6443
labels:
component: kube-apiserver
tier: control-plane
name: kube-apiserver
namespace: kube-system
spec:
containers:
- command:
- kube-apiserver
- --advertise-address=10.0.0.5
- --allow-privileged=true
- --authorization-mode=Node,RBAC
- --audit-policy-file=/etc/kubernetes/log-policy/audit-policy.yaml #Add this
- --audit-log-path=/var/log/kubernetes/logs.txt #Add this
- --audit-log-maxage=5 #Add this
- --audit-log-maxbackup=10 #Add this
...
output truncated
Note: log volume & policy volume is already mounted in vim /etc/kubernetes/manifests/kube-apiserver.yaml so no need to mount it.
Reference: https://kubernetes.io/docs/tasks/debug-application-cluster/audit/
Question 30
Context
AppArmor is enabled on the cluster's worker node. An AppArmor profile is prepared, but not enforced yet.
Task
On the cluster's worker node, enforce the prepared AppArmor profile located at
/etc/apparmor.d/nginx_apparmor.
Edit the prepared manifest file located at /home/candidate/KSSH00401/nginx-pod.yaml to apply the AppArmor profile.
Finally, apply the manifest file and create the Pod specified in it.
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