OpenShift Cheatsheet

Here some helpful OpenShift commands which work (at least) since version >= 4.11

How to get a token: https://oauth-openshift.apps.ocp.example.com/oauth/token/display

You might need it for login or automatization.

Switch namespace:

$ oc project <namespace>

quit namespace:

$ oc project -n default

Get all resources:

$ oc get all

Get status of all nodes:

$ oc get nodes

Show Uptime:

$ oc get machines -A

Sort Events by time:

$ oc get events --sort-by=metadata.creationTimestamp

Show/edit initial configuration:

$ oc get cm cluster-config-v1 -o yaml -n kube-system
  (edit)

Information gathering: https://docs.openshift.com/container-platform/4.12/cli_reference/openshift_cli/administrator-cli-commands.html#oc-adm-inspect (evtl. secrets löschen!)

List alerts:

$ oc -n openshift-monitoring exec -ti alertmanager-main-0 -c alertmanager -- amtool alert --alertmanager.url=http://localhost:9093 -o extended
List silences:
$ oc -n openshift-monitoring exec -ti alertmanager-main-0 -c alertmanager -- amtool silence query --alertmanager.url http://localhost:9093

https://cloud.redhat.com/blog/how-to-use-amtool-to-manage-red-hat-advanced-cluster-management-for-kubernetes-alerts

Patch resource:

$ oc patch installplan install-defgh -n openshift-operators-redhat --type merge  --patch '{"spec":{"approved":true}}'

Get state paused/not paused of machineconfigpool:

$ oc get mcp worker -o jsonpath='{.spec.paused}'

Set master/worker to (un)paused:

$ oc patch --type=merge --patch='{"spec":{"paused":false}}' machineconfigpool/{master,worker}

Liveness/Readiness Probes of all pods in certain timestamp:

$ oc adm node-logs --role worker -u kubelet | egrep -E 'Liveness|Readiness' | grep "Aug 21 11:22"

Useful terms

IPI Installer-provisioned infrastructure cluster
Cluster installed by install command; user must only provide some information (which platform, cluster name, network, storage, ...)

UPI User provisioned infrastructure cluster

• DNS and Loadbalancing must already be there
• Installation manually, download ova file (in case of vSphere)
• master created manually
• workers recommended
• *no* keepalived

Advantages:
IPI: installation more simple, using preconfigured features
UPI: more flexibility, no loadbalancer outage during update

Change from IPI -> UPI not possible

cm	config map
csv	cluster service version
dc	deploymentconfig
ds	deploymentsetting
ip	installplan
mcp	machineconfigpool
pv	persistent volume
sa	service account
scc	security context constraints
svc	service