Deploying and Managing Applications on an OpenShift Cluster

Question 1

Definition CRDs

Answer 1

Custom Resource Definitions (CRDs) are resource types stored in Etcd and managed by
Kubernetes. These resource types form the state and configuration of all resources managed
by OpenShift.

Question 2

Definition Etcd

Answer 2

Etcd is a distributed key-value store, used by Kubernetes to store configuration and state information about the containers and other resources inside the Kubernetes cluster.

Question 3

Node

Answer 3

A server that hosts applications in an OpenShift cluster.

Question 4

Master Node

Answer 4

A node server that manages the control plane in an OpenShift cluster. Master nodes provide basic cluster services such as APIs or controllers.

Question 5

Worker Node

Answer 5

Also called a Compute Node, worker nodes execute workloads for the cluster. Application pods are scheduled onto worker nodes.

Question 6

Resource

Answer 6

Resources are any kind of component definition managed by OpenShift. Resources contain the configuration of the managed component (for example, the role assigned to a node), and the current state of the component (for example, if the node is available).

Question 7

Controller

Answer 7

A controller is an OpenShift component that watches resources and makes changes attempting to move the current state towards the desired state

Question 8

Label

Answer 8

A key-value pair that can be assigned to any OpenShift resource. Selectors use labels to filter eligible resources for scheduling and other operations.

Question 9

Namespace or Project

Answer 9

A scope for OpenShift resources and processes, so that resources with the same name can be used in different contexts.

Question 10

Console

Answer 10

A web UI provided by OpenShift that allows developers and administrators to manage cluster resources.

Question 11

Operators

Answer 11

Operators are Kubernetes plug-in components that can react to cluster events and control the state of resources. Operators and the Operator Framework are outside the scope of this course.

Question 12

Pods

Answer 12

(pod)
Collections of containers that share resources, such as IP addresses and persistent storage volumes. Pods are the basic unit of work for OpenShift.

Question 13

Services

Answer 13

(svc)
Specific IP/port combinations that provides access to a pool of pods. By default, services connect clients to pods in a round-robin fashion.

Question 14

Replication Controllers

Answer 14

(rc)
OpenShift resources that define how pods are replicated (horizontally scaled) to different nodes. Replication controllers are a basic OpenShift service to provide high availability for pods and containers.

Question 15

Persistent Volumes

Answer 15

(pv)

Storage areas to be used by pods.

Question 16

Persistent Volume Claims

Answer 16

(pvc)

Persistent Volume Claims (pvc)

Question 17

Config Maps

Answer 17

(cm)
A set of keys and values that can be used by other resources. ConfigMaps and Secrets are usually used to centralize configuration values used by several resources. Secrets differ from ConfigMaps maps in that Secrets are used to store sensitive data (usually encrypted), and their access is restricted to fewer authorized users.

Question 18

Deployment Configs

Answer 18

(dc)
A set of containers included in a pod, and the deployment strategies to be used. A dc also provides a basic but extensible continuous delivery workflow.

Question 19

Build Configs

Answer 19

(bc)
A process to be executed in the OpenShift project. The OpenShift Source-to-Image (S2I) feature uses BuildConfigs to build a container image from application source code stored in a Git repository. A bc works together with a dc to provide a basic but extensible continuous integration and continuous delivery workflows.

Question 20

Routes

Answer 20

DNS host names recognized by the OpenShift router as an ingress point for various applications and microservices deployed on the cluster.

Question 21

Image Streams

Answer 21

(is)
An image stream and its tags provide an abstraction for referencing container images from within OpenShift Container Platform. The image stream and its tags allow you to track what images are available and ensure that you are using the specific image you need even if the image in the repository changes. Image streams do not contain actual image data, but present a virtual view of related images, similar to an image repository.