EX380 Sample Questions Answers

Step 1: Confirm that the repository being pushed to is the same repository watched by the GitOps/Argo CD application.

This linkage is essential because GitOps acts only on configured source repositories and paths.

Step 2: Commit the MachineConfig changes.

The lab uses:

git commit -am "Add MachineConfig for motd"

Step 3: Push the changes to the tracked branch.

The lab uses:

git push origin main

Step 4: Allow Argo CD to detect the repository change and begin synchronization.

In a standard GitOps model, the controller compares the Git repository to the cluster state and applies drift correction or new desired resources.

Detailed explanation:

This sub Task SIMULATION is the operational purpose behind the previous Git command Task SIMULATION . The point is not merely to store a file in Git; it is to update the declarative source that Argo CD uses to reconcile the cluster. Once the repository is updated, Argo CD detects the new commit and syncs the MachineConfig into the cluster according to its application definition. This demonstrates a core automation principle in OpenShift GitOps: administrators do not treat the cluster as the primary editable surface. Instead, they modify Git and let the automation layer enforce state. That provides traceability, peer review potential, rollback capability, and consistency across environments.

Annotate the namespace with default tolerations

oc annotate ns payments \

scheduler.alpha.kubernetes.io/defaultTolerations='[{"key":"dedicated","operator":"Equal","value":"payments","effect":"NoSchedule"}]' \

--overwrite

Some clusters honor this pattern; if not, the fallback is mutating admission or editing workloads.

Create a new pod/deployment in the namespace

Then verify its spec includes tolerations:

oc -n payments get pod < pod > -o yaml | grep -n tolerations -A5

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Create the MachineConfig YAML (example content encoded in base64)

apiVersion: machineconfiguration.openshift.io/v1

kind: MachineConfig

metadata:

name: 99-worker-motd

labels:

machineconfiguration.openshift.io/role: worker

spec:

config:

ignition:

version: 3.2.0

storage:

files:

- path: /etc/motd

mode: 0644

contents:

source: data:text/plain;charset=utf-8;base64,VGhpcyBpcyBhIHdvcmtlciBub2RlLg==

MachineConfig uses Ignition format; file content is typically base64.

Apply it

oc apply -f 99-worker-motd.yaml

Watch worker MachineConfigPool roll out

oc get mcp worker

MCP will show Updating then Updated.

Validate on a worker node (if you have node access)

Confirm /etc/motd contains the expected text.

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Step 1: Confirm the service account exists in auth-audit.

It must exist before a role can be assigned to it.

Step 2: Run the command:

oc adm policy add-cluster-role-to-user cluster-reader system:serviceaccount:auth-audit:audit

Step 3: Verify the binding is added.

The lab output shows:

clusterrole.rbac.authorization.k8s.io/cluster-reader added: "system:serviceaccount:auth-audit:audit"

Detailed explanation:

This binds the cluster-reader cluster role to the audit service account. The full subject format system:serviceaccount:namespace:name is required because OpenShift RBAC needs the exact service account identity. The cluster-reader role is broader than a project-scoped view role because it allows read-level access across cluster resources. This is appropriate for auditing or inspection use cases where the account must observe but not modify. The distinction between cluster roles and namespaced roles is important: cluster roles apply to non-namespaced resources and broad cluster visibility, while local roles are limited to individual projects. This Task is a classic RBAC operation that combines identity creation with controlled privilege assignment.

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Step 1: Make sure the MachineConfig YAML has already been created or modified in the local Git repository.

This Task assumes the file change is ready to be committed.

Step 2: Run the command:

git commit -am "Add MachineConfig for motd" & & git push origin main

Step 3: Verify the commit succeeds and the push goes to the main branch.

The lab output shows:

[main 8d32a1] Add MachineConfig for motd

Detailed explanation:

This Task is part of a GitOps workflow. Instead of manually applying changes directly to the cluster, the desired configuration is stored in Git, and a GitOps controller such as Argo CD synchronizes the cluster to match the repository state. The command commits all tracked modified files with the message Add MachineConfig for motd and then pushes the change to the main branch. In this model, Git becomes the source of truth. A MachineConfig is typically used to manage node-level operating system configuration in OpenShift, so pushing it through GitOps ensures the change is auditable, repeatable, and reconciled declaratively. If the commit does not include the intended YAML, the synchronization mechanism will not apply the desired change.

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Step 1: Identify the pending certificate signing request.

The lab names it audit-csr.

Step 2: Run the approval command:

oc adm certificate approve audit-csr

Step 3: Confirm approval.

The lab output shows:

certificatesigningrequest.certificates.k8s.io/audit-csr approved

Detailed explanation:

In Kubernetes and OpenShift, a CSR must be approved before the requester can use the signed certificate for authentication. This Task approves the CSR named audit-csr, which is likely associated with the audit user or service account access flow in the lab. Certificate-based authentication is commonly used for kubeconfig access because it enables secure client identity without relying solely on tokens. Until the CSR is approved, the certificate cannot be trusted by the cluster API for authenticated operations. Administrative approval is therefore a gatekeeping step that ensures only intended certificate requests become valid credentials. This Task is part of a broader kubeconfig workflow that continues with setting credentials and defining context.

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Create a group sync config file (example groupsync.yaml)

This file defines how OpenShift queries LDAP for groups and members.

Run a one-time group sync

oc adm groups sync --sync-config=groupsync.yaml --confirm

--confirm actually applies changes (without it, it’s a dry-run preview).

Verify groups created/updated

oc get groups

oc describe group < groupname >

Confirms group objects exist and membership is present.

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Step 1: Ensure the certificate file rhds_ca.crt is available in your current working directory or use the correct path.

The Task requires creating a configmap from this CA certificate file.

Step 2: Run the command:

oc create configmap rhds-ca-config-map --from-file ca.crt=rhds_ca.crt -n openshift-config

Step 3: Confirm the configmap is created.

The lab output shows:

configmap/rhds-ca-config-map created

Detailed explanation:

This creates a configmap named rhds-ca-config-map in the openshift-config namespace and maps the local file rhds_ca.crt to the key name ca.crt inside the configmap. This is important in external identity integration because OpenShift may need to trust a custom certificate authority when communicating with LDAP or another secured external service. By placing the certificate in a configmap, the authentication operator or related cluster configuration can reference it cleanly. The key name matters because many OpenShift resources expect a CA bundle key with a specific filename-like convention. If the file path is wrong, the command fails immediately. If the configmap name or key mapping is wrong, the authentication provider referencing it may not trust the external endpoint.

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Generate private key and CSR

openssl genrsa -out audit2.key 2048

openssl req -new -key audit2.key -out audit2.csr -subj "/CN=audit2/O=auditors"

CN becomes username; O can map to groups in some setups.

Base64 encode CSR for the API object

CSR=$(base64 -w0 audit2.csr)

Kubernetes CSR object expects base64-encoded request data.

Create the CSR object

cat < < EOF | oc apply -f -

apiVersion: certificates.k8s.io/v1

kind: CertificateSigningRequest

metadata:

name: audit2-csr

spec:

request: ${CSR}

signerName: kubernetes.io/kube-apiserver-client

usages:

- client auth

EOF

Approve the CSR

oc adm certificate approve audit2-csr

Approval triggers certificate issuance.

Extract the signed certificate

oc get csr audit2-csr -o jsonpath='{.status.certificate}' | base64 -d > audit2.crt

Produces the client certificate file.

Build kubeconfig using cert/key

oc config set-credentials audit2 \

--client-certificate=audit2.crt --client-key=audit2.key \

--embed-certs=true --kubeconfig=audit2.kubeconfig

oc config set-cluster lab \

--server="$(oc whoami --show-server)" \

--insecure-skip-tls-verify=true \

--kubeconfig=audit2.kubeconfig

oc config set-context audit2 \

--cluster=lab --user=audit2 --namespace=default \

--kubeconfig=audit2.kubeconfig

Creates a kubeconfig that authenticates using client certificates.

Test

oc --kubeconfig=audit2.kubeconfig get ns

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