Manage_OCP.md

Manage OpenShift Container Platform

• Manage OpenShift Container Platform
  • Use the command-line interface to manage and configure an OpenShift cluster
  • Use the web console to manage and configure an OpenShift cluster
  • Create and delete projects
  • Import, export, and configure Kubernetes resources
  • Examine resources and cluster status
  • View logs
  • Monitor cluster events and alerts
  • Troubleshoot common cluster events and alerts
  • Use product documentation

https://docs.openshift.com/container-platform/4.10/nodes/index.html

Executing troubleshooting commands:

• Getting node informations:

oc get node
oc describe node <nodename>

• Getting busiest nodes

oc adm top nodes

• Getting journalctl logs from a node

oc adm node-logs -u kubelet my-node-name

• Running a remote shell for a node

oc debug node/<nodename>

• Work with cluster installers

oc get clusteroperators
oc get clusterversion -o yaml

• Getting a pod logs

oc logs <pod> [-c <container>] [-f]

• Debugging a deployment or a pod

oc debug deployment/<deplname> [--as-root]
oc rsh <podname>
oc port-forward <pod> <localport>:<remoteport>

• Getting a file from a pod

oc cp file <pod>:/file
oc cp <pod>:/file file

Secret

Creating secret:

apiVersion: v1
kind: Secret
metadata:
  name: test-secret
type: Opaque 
data: 
  username: dXNlcjEK
  password: cGFzc3dvcmQK
stringData: 
  hostname: myapp.mydomain.com
  secret.properties: |
    property1=valueA
    property2=valueB

Consuming secret in Pod:

# Using as file
apiVersion: v1
kind: Pod
metadata:
  name: secret-example-pod
spec:
  containers:
    - name: secret-test-container
      image: busybox
      command: [ "/bin/sh", "-c", "cat /etc/secret-volume/*" ]
      volumeMounts: 
          - name: secret-volume
            mountPath: /etc/secret-volume 
            readOnly: true 
  volumes:
    - name: secret-volume
      secret:
        secretName: test-secret 
  restartPolicy: Never
  
# Using as environment variable  
apiVersion: v1
kind: Pod
metadata:
  name: secret-example-pod
spec:
  containers:
    - name: secret-test-container
      image: busybox
      command: [ "/bin/sh", "-c", "export" ]
      env:
        - name: TEST_SECRET_USERNAME_ENV_VAR
          valueFrom:
            secretKeyRef: 
              name: test-secret
              key: username
  restartPolicy: Never

Using secret in Service Account:

apiVersion: v1
kind: ServiceAccount
 ...
secrets:
- name: test-secret

https://docs.openshift.com/container-platform/4.10/nodes/pods/nodes-pods-secrets.html