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Chapter 4. Using the oc tool
The optional OpenShift CLI (oc) tool provides a subset of oc commands for Red Hat build of MicroShift deployments. Using oc is convenient if you are familiar with OpenShift Container Platform and Kubernetes.
4.1. About the OpenShift CLI
With the OpenShift command-line interface (CLI), the oc command, you can deploy and manage Red Hat build of MicroShift projects from a terminal. The CLI oc tool is ideal in the following situations:
- Working directly with project source code
- Scripting Red Hat build of MicroShift operations
- Managing projects while restricted by bandwidth resources
A kubeconfig file must exist for the cluster to be accessible. The values are applied from built-in default values or a config.yaml, if one was created.
4.2. Using the OpenShift CLI in Red Hat build of MicroShift
Review the following sections to learn how to complete common tasks in Red Hat build of MicroShift using the oc CLI.
4.2.1. Viewing pods
Use the oc get pods command to view the pods for the current project.
When you run oc inside a pod and do not specify a namespace, the namespace of the pod is used by default.
$ oc get pods -o wide
Example output
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE cakephp-ex-1-build 0/1 Completed 0 5m45s 10.131.0.10 ip-10-0-141-74.ec2.internal <none> cakephp-ex-1-deploy 0/1 Completed 0 3m44s 10.129.2.9 ip-10-0-147-65.ec2.internal <none> cakephp-ex-1-ktz97 1/1 Running 0 3m33s 10.128.2.11 ip-10-0-168-105.ec2.internal <none>
4.2.2. Viewing pod logs
Use the oc logs command to view logs for a particular pod.
$ oc logs cakephp-ex-1-deploy
Example output
--> Scaling cakephp-ex-1 to 1 --> Success
4.2.3. Listing supported API resources
Use the oc api-resources command to view the list of supported API resources on the server.
$ oc api-resources
Example output
NAME SHORTNAMES APIGROUP NAMESPACED KIND bindings true Binding componentstatuses cs false ComponentStatus configmaps cm true ConfigMap ...
4.3. Getting help
You can get help with CLI commands and Red Hat build of MicroShift resources in the following ways.
Use
oc help --flagto get information about a specific CLI command:Example: Get help for the
oc createcommand$ oc create --help
Example output
Create a resource by filename or stdin JSON and YAML formats are accepted. Usage: oc create -f FILENAME [flags] ...
Use the
oc explaincommand to view the description and fields for a particular resource:Example: View documentation for the
Podresource$ oc explain pods
Example output
KIND: Pod VERSION: v1 DESCRIPTION: Pod is a collection of containers that can run on a host. This resource is created by clients and scheduled onto hosts. FIELDS: apiVersion <string> 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. More info: https://git.k8s.io/community/contributors/devel/api-conventions.md#resources ...
4.4. oc command errors in Red Hat build of MicroShift
Not all OpenShift CLI (oc) tool commands are relevant for Red Hat build of MicroShift deployments. When you use oc to make a request call against an unsupported API, the oc binary usually generates an error message about a resource that cannot be found.
Example output
For example, when the following new-project command is run:
$ oc new-project test
The following error message can be generated:
Error from server (NotFound): the server could not find the requested resource (get projectrequests.project.openshift.io)
And when the get projects command is run, another error can be generated as follows:
$ oc get projects error: the server doesn't have a resource type "projects"
