Troubleshooting OpenShift Flashcards
Display the list of nodes in a cluster
oc get nodes
Displays the current CPU and memory usage of each node
oc adm top nodes
Displays the resources used by a node
oc describe node my-node-name
Show the cluster version
oc get clusterversion
Show elaborated details about the cluster status
oc describe clusterversion
List all cluster operators
oc get clusteroperators
View crio logs on a given node
oc adm node-logs -u crio my-node-name
View kubelet logs on a given node
oc adm node-logs -u kubelet my-node-name
View all journal logs on a given node
oc adm node-logs my-node-name
Login into a node and check if kubelete is running
oc debug node/my-node-name
chroot /host
systemctl is-active kubelet
Login into a node and show low-level information about all local containers running on the node
oc debug node/my-node-name
chroot /host
crictl ps
Display a pod logs
oc logs my-pod-name
Display a container logs
oc logs my-pod-name -c my-container-name
Run a given deployment as root
oc debug deployment/my-deployment-name –as-root
Change a pod log level to shows max amount of information
oc get pods –loglevel 10
Extract your oc login token so you can use it in a curl request
oc whoami -t
Opens a shell inside a pod to run shell commands
oc rsh my-pod-name
Copies local files to a location inside a pod
oc cp /local/path my-pod-name:/container/path
Creates a TCP tunnel from local-port on your workstation to local-port on the pod
oc port-forward my-pod-name local-port:remote-port
List storage classes of a cluster
oc get storageclass
Add a volume to an application
oc set volumes deployment/example-application –add
–name example-pv-storage
–type pvc
–mount-path /var/lib/example-app
–claim-class nfs-storage
–claim-mode rwo
–claim-size 15Gi
–claim-name example-pv-claim
Delete a volume
oc delete pvc/example-pvc-storage
List cluster nodes using admin cert as opposed to login/password
oc –kubeconfig /home/user/auth/kubeconfig get nodes
Delete kubeadmin user
oc delete secret kubeadmin -n kube-system
List all pods inside internal image registry project
oc get pod -n openshift-image-registry
Tail the logs of the internal image reg operator
1) Determine the pod name with: oc get pod -n openshift-image-registry
2) oc logs -f OPERATOR-POD-NAME -n openshift-image-registry
Verify that etc is running
1) oc debug node/master01
2) chroot /host
3) crictl ps –name etcd
Check if an image exist on image registry
skopeo inspect docker://registry.redhat.io/rhel8/postgresql-13:1
App was created with typo in image reg. How to fix it?
1) Find the right image. Use skopeo to inspect
2) oc edit deployment/deployment-name
When you create a storage volume, you need to provide a parameter claim-class. How do you obtain values for this parameter?
oc get storageclasses
Content to add to Oauth.yaml when adding htpasswd identify provider
Steps to add a htpasswd provider
1) Create htpasswd file and populate it
2) Create secret with htpasswd file
3) Assign admin users the cluster-admin role
4) Extract oauth
5) Add identity provider to oauth.yaml
6) Replace oauth.yaml
Check what happened to a failed app
1) oc get pods
2) oc get status
3) oc get events
4) skopeo inspect docker://registry.redhat.io/rhel8/postgresq-13:1
5) oc edit deployment/psql
Different volum access modes
rwx: vol can be mounted as read-write by many nodes.
rwo: vol can be mounted as read-write by a single node
rox: vol can be mounted as read-only by many nodes
