Red Hat OpenShift

Commands

Command	Used for...	Notes
oc whoami	See who you are logged in as
oc login	Log in to the cluster	Defaults to using a web login, but user/pass can be provided over the command line
oc new-project	Create a new project (namespace)
oc describe	Get detailed information on a resource instance
oc explain	Get documentation on a resource object
oc api-resources	Get a list of all API resources	--api-group can be used to limit to certain API groups
oc adm top	Get resource usage on pods and similar	--sum will show a sum of resource usage
oc events	Get high-level logs	Helpful for things like image pull or pvc issues
oc debug	Open a shell session in the pod or node	Uses the first container by default, but as a copy; can also be used to log in to physical nodes
oc rsh	Open a shell session in a pod	Simpler version of `oc exec`
oc attach -it	Connect and create an interactive session with a pod
oc port-forward	Expose a pod's port on the localhost
oc image	Get info about an image
oc edit	Make an edit to a resource's YAML and apply it	Useful for modifying the resource easily or in multiple ways
oc patch	Make an edit to a resource's field and apply it	Useful for very specific edits
oc cp	Copy a file into or out of a pod
oc rsync	Copy a file into or out of a pod	Requires the rsync binary on both host and pod container
skopeo list-tags	List all tags for a given image
skopeo inspect	Get image info like env variables and tags

Commands to avoid using:

Command	Used for	Use instead	Because
oc run	Create a single pod	oc create deployment	Includes replicas and other stuff
oc exec -it /bin/bash	Open remote connection	oc rsh	Simpler

Important Resource Types

Resource	Description	Useful for...	OS Only?
template	YAML manifest of multiple resources	creating multiple resources at once	Yes
pod	One or more containers; represents a single app		No
Deployment	Represents pod templates along with replica sets	Deploying pods with replicas	No
StatefulSet	Create a set of unique pods	Databases
DaemonSet	Runs copies of pods on every node	storage daemons, log collectors, monitoring	No
project	OpenShift's namespaces	RBAC	Yes
service	pod-to-pod networking + DNS		No
PersistentVolumeClaim	persistent storage		No
Secret	Configs or other data that needs to be kept secure	SSH keys, API keys, OAuth tokens, passwords	No
Job	One-off tasks	Initialize database, create/restore from backup	No
CronJob	Scheduled tasks	Backups	No

Pods

• Runs a single app
• Can include multiple containers
• Containers within the pod can share storage/networking

Networking

Anki Questions

1. What is <resource>?
2. What command should be used to <action>?
3. Where is <resource> useful compared to similar ones?