# Guided Exercise: The Kubernetes and OpenShift Command-Line Interfaces
Access an OpenShift cluster using the command-line to get information about cluster services and nodes.
**Outcomes**
* Use the OpenShift web console to locate the installation file for the `oc` OpenShift command-line interface.
* Get and use a token from the web console to access the cluster from the command line.
* Identify key differences between the `kubectl` and `oc` command-line tools.
* Identify the main components of OpenShift and Kubernetes.
As the `student` user on the `workstation` machine, use the `lab` command to prepare your system for this exercise.
This command ensures that all resources are available for this exercise.
```plaintext
[student@workstation ~]$ lab start cli-interfaces
```
**Procedure 2.1. Instructions**
1. Log in to the OpenShift web console as the `developer` user. Locate the installation file for the `oc` OpenShift command-line interface (CLI).
1. Open a web browser and then navigate to [`https://console-openshift-console.apps.ocp4.example.com`](https://console-openshift-console.apps.ocp4.example.com).
2. Click **Red Hat Identity Management** and log in as the `developer` user with the `developer` password.
3. Locate the installation file for the `oc` CLI. From the OpenShift web console, select **Help** → **Command line tools**. The **Help** menu is represented by a `?` icon.
![](https://rol.redhat.com/rol/static/static_file_cache/do180-4.12/cli/interfaces/assets/tools_screen.png align="center")
The `oc` binary is available for multiple operating systems and architectures. For each operating system and architecture, the `oc` binary also includes the `kubectl` binary.
### **NOTE**
You do not need to download or install the `oc` and `kubectl` binaries, which are already installed on the `workstation` machine.
2. Download an authorization token from the web console. Then, use the token and the `oc` command to log in to the OpenShift cluster.
1. From the **Command Line Tools** page, click the **Copy login command** link.
2. The link opens a login page. Click **Red Hat Identity Management** and log in as the `developer` user with the `developer` password.
3. A web page is displayed. Click the **Display token** link to show your API token and the login command.
4. Copy the `oc login` command to your clipboard. Open a terminal window and then use the copied command to log in to the cluster with your token.
```plaintext
[student@workstation ~]$ oc login --token=sha256-fypX...Ot6A \
--server=https://api.ocp4.example.com:6443
Logged into "https://api.ocp4.example.com:6443" as "developer" using the token provided.
...output omitted...
```
3. Compare the available commands for the `kubectl` and `oc` commands.
1. Use the `help` command to list and review the available commands for the `kubectl` command.
```plaintext
[student@workstation ~]$ kubectl help
kubectl controls the Kubernetes cluster manager.
Find more information at: https://kubernetes.io/docs/reference/kubectl/
Basic Commands (Beginner):
create Create a resource from a file or from stdin
expose Take a replication controller, service, deployment or pod and expose it as a new Kubernetes service
run Run a particular image on the cluster
set Set specific features on objects
Basic Commands (Intermediate):
explain Get documentation for a resource
get Display one or many resources
edit Edit a resource on the server
delete Delete resources by file names, stdin, resources and names, or by resources and label selector
...output omitted....
```
Notice that the `kubectl` command does not provide a `login` command.
2. Examine the available subcommands and options for the `kubectl create` command by using the `--help` option.
```plaintext
[student@workstation ~]$ kubectl create --help
Create a resource from a file or from stdin.
JSON and YAML formats are accepted.
Examples:
# Create a pod using the data in pod.json
kubectl create -f ./pod.json
...output omitted....
Available Commands:
clusterrole Create a cluster role
clusterrolebinding Create a cluster role binding for a particular cluster role
configmap Create a config map from a local file, directory or literal value
cronjob Create a cron job with the specified name
deployment Create a deployment with the specified name
...output omitted...
Options:
--allow-missing-template-keys=true:
If true, ignore any errors in templates when a field or map key is missing in the template. Only applies to
golang and jsonpath output formats.
--dry-run='none':
Must be "none", "server", or "client". If client strategy, only print the object that would be sent, without
sending it. If server strategy, submit server-side request without persisting the resource.
...output omitted....
Usage:
kubectl create -f FILENAME [options]
Use "kubectl --help" for more information about a given command.
Use "kubectl options" for a list of global command-line options (applies to all commands).
```
You can use the `--help` option with any `kubectl` command. The `--help` option provides information about a command, including the available subcommands and options, and the command syntax.
3. List and review the available commands for the `oc` binary by using the `help` command.
```plaintext
[student@workstation ~]$ oc help
OpenShift Client
This client helps you develop, build, deploy, and run your applications on any
OpenShift or Kubernetes cluster. It also includes the administrative
commands for managing a cluster under the 'adm' subcommand.
Basic Commands:
login Log in to a server
new-project Request a new project
new-app Create a new application
status Show an overview of the current project
project Switch to another project
projects Display existing projects
explain Get documentation for a resource
...output omitted....
```
The `oc` command supports the same capabilities as the `kubectl` command. The `oc` command provides additional commands to natively support an OpenShift cluster. For example, the `new-project` command creates a project, which is a Kubernetes namespace, in the OpenShift cluster. The `new-app` command is unique to the `oc` command. It creates applications by using existing source code or prebuilt images.
4. Use the `--help` option with the `oc create` command to view the available subcommands and options.
```plaintext
[student@workstation ~]$ oc create --help
Create a resource from a file or from stdin.
JSON and YAML formats are accepted.
Examples:
# Create a pod using the data in pod.json
oc create -f ./pod.json
...output omitted...
Available Commands:
build Create a new build
clusterresourcequota Create a cluster resource quota
clusterrole Create a cluster role
clusterrolebinding Create a cluster role binding for a particular cluster role
configmap Create a config map from a local file, directory or literal value
cronjob Create a cron job with the specified name
deployment Create a deployment with the specified name
deploymentconfig Create a deployment config with default options that uses a given image
...output omitted....
Options:
--allow-missing-template-keys=true:
If true, ignore any errors in templates when a field or map key is missing in the template. Only applies to
golang and jsonpath output formats.
--dry-run='none':
Must be "none", "server", or "client". If client strategy, only print the object that would be sent, without
sending it. If server strategy, submit server-side request without persisting the resource.
...output omitted...
Usage:
oc create -f FILENAME [options]
....output omitted....
```
The `oc create` command includes the same subcommands and options as the `kubectl create` command, and provides additional subcommands for OpenShift resources. For example, you can use the `oc create` command to create OpenShift resources such as a deployment configuration, a route, and an image stream.
4. Identify the components and Kubernetes resources of an OpenShift cluster by using the terminal. Unless otherwise noted, all commands are available for the `oc` and `kubectl` commands.
1. In a terminal, use the `oc login` command to log in to the cluster as the `admin` user with the `redhatocp` password. Regular cluster users, such as the `developer` user, cannot list resources at a cluster scope.
```plaintext
[student@workstation ~]$ oc login -u admin -p redhatocp
Login successful
...output omitted...
```
2. Identify the cluster version with the `version` command.
```plaintext
[student@workstation ~]$ oc version
Client Version: 4.12.0
Kustomize Version: v4.5.7
Server Version: 4.12.0
Kubernetes Version: v1.25.4+77bec7a
```
3. Use the `cluster-info` command to identify the URL for the Kubernetes control plane.
```plaintext
[student@workstation ~]$ oc cluster-info
Kubernetes control plane is running at https://api.ocp4.example.com:6443
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
```
4. Identify the supported API versions by using the `api-versions` command.
```plaintext
[student@workstation ~]$ oc api-versions
admissionregistration.k8s.io/v1
apiextensions.k8s.io/v1
apiregistration.k8s.io/v1
apiserver.openshift.io/v1
apps.openshift.io/v1
apps/v1
...output omitted....
```
5. List cluster operators with the `get clusteroperator` command.
```plaintext
[student@workstation ~]$ oc get clusteroperator
NAME VERSION AVAILABLE PROGRESSING DEGRADED SINCE ...
authentication 4.12.0 True False False 18d
baremetal 4.12.0 True False False 18d
cloud-controller-manager 4.12.0 True False False 18d
cloud-credential 4.12.0 True False False 18d
cluster-autoscaler 4.12.0 True False False 18d
config-operator 4.12.0 True False False 18d
console 4.12.0 True False False 18d
control-plane-machine-set 4.12.0 True False False 18d
csi-snapshot-controller 4.12.0 True False False 18d
dns 4.12.0 True False False 5h24m
etcd 4.12.0 True False False 18d
image-registry 4.12.0 True False False 18d
ingress 4.12.0 True False False 18d
...output omitted...
```
6. Use the `get` command to list pods in the `openshift-api` project. Specify the project with the `-n` option.
```plaintext
[student@workstation ~]$ oc get pods -n openshift-apiserver
NAME READY STATUS RESTARTS AGE
apiserver-68c9485699-ndqlc 2/2 Running 2 18d
```
7. Use the `oc status` command to retrieve the status of resources in the `openshift-authentication` project.
```plaintext
[student@workstation ~]$ oc status -n openshift-authentication
In project openshift-authentication on server https://api.ocp4.example.com:6443
https://oauth-openshift.apps.ocp4.example.com (passthrough) to pod port 6443 (svc/oauth-openshift)
deployment/oauth-openshift deploys quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:7d75...6c86
deployment #7 running for 2 weeks - 1 pod
deployment #6 deployed 2 weeks ago
deployment #4 deployed 2 weeks ago
deployment #3 deployed 2 weeks ago
deployment #2 deployed 2 weeks ago
deployment #1 deployed 2 weeks ago
...output omitted...
```
8. Use the `explain` command to list the description and available fields for `services` resources.
```plaintext
[student@workstation ~]$ oc explain services
KIND: Service
VERSION: v1
DESCRIPTION:
Service is a named abstraction of software service (for example, mysql)
consisting of local port (for example 3306) that the proxy listens on, and
the selector that determines which pods will answer requests sent through
the proxy.
FIELDS:
apiVersion
APIVersion defines the versioned schema of this representation of an
object. Servers should convert recognized schemas to the latest internal
value, and may reject unrecognized values.
...output omitted...
```
9. Use the `get` command to list cluster nodes.
```plaintext
[student@workstation ~]$ oc get nodes
NAME STATUS ROLES AGE VERSION
master01 Ready control-plane,master,worker 18d v1.25.4+77bec7a
```
A single node exists in the cluster.
**Finish**
On the `workstation` machine, use the `lab` command to complete this exercise. This step is important to ensure that resources from previous exercises do not impact upcoming exercises.
```plaintext
[student@workstation ~]$ lab finish cli-interfaces
```