Introducing Red Hat OpenShift 4

Part1: An Introduction to Kubernetes

bit.ly/v4intro-part1

April 16, 2019, 11:00 a.m. PDT

presented by Ryan Jarvinen (@RyanJ), Developer Advocate at Red Hat

Including a highly-available

Control Plane

A group of machines (nodes) that are responsible for hosting core platform services

Starting a Pod from the Command-Line

Create a new resource from a json object specification:

kubectl create -f https://raw.githubusercontent.com/jankleinert/hello-workshop/master/pod.json

{
  "kind": "Pod",
  "apiVersion": "v1",
  "metadata": {
    "creationTimestamp": null,
    "name": "hello-k8s",
    "labels": {
      "run": "hello-k8s"
    }
  },
  "spec": {
    "containers": [
      {
        "name": "hello-k8s",
        "image": "jkleinert/devweek-workshop",
        "ports": [
          {
            "containerPort": 8080
          }
        ],
        "resources": {}
      }
    ]
  }
}

Contacting your App

Expose the pod by creating a new service (or "loadbalancer"):

kubectl expose pod/hello-k8s --port 8080 --type=NodePort

Schedule the deletion of all pods that are labeled with:

kubectl get pods -l run=hello-k8s

kubectl delete pods -l run=hello-k8s

Delete the service:

kubectl delete service hello-k8s

Create a specification for your deployment:

kubectl run hello-k8s --image=jkleinert/nodejsint-workshop \
--dry-run -o json > deployment.json

View the generated deployment spec file:

cat deployment.json

{
    "kind": "Deployment",
    "apiVersion": "apps/v1beta1",
    "metadata": {
        "name": "hello-k8s",
        "creationTimestamp": null,
        "labels": {
            "run": "hello-k8s"
        }
    },
    "spec": {
        "replicas": 1,
        "selector": {
            "matchLabels": {
                "run": "hello-k8s"
            }
        },

        "template": {
            "metadata": {
                "creationTimestamp": null,
                "labels": {
                    "run": "hello-k8s"
                }
            },
            "spec": {
                "containers": [
                    {
                        "name": "hello-k8s",
                        "image": "jkleinert/nodejsint-workshop",
                        "resources": {}
                    }
                ]
            }
        },
        "strategy": {}
    },
    "status": {}
}

Create a new deployment from your local spec file:

kubectl create -f deployment.json

This action should set spec.replicas to 1

Create a Service spec to direct traffic:

kubectl expose deploy/hello-k8s --type=NodePort --port=8080 --dry-run -o json > service.json

View the resulting spec file:

cat service.json

Create a new service from your local spec file:

kubectl create -f service.json

List multiple resources by type:

kubectl get po,svc,deploy

Connect to your new deployment via the associated service port:

curl $(minishift ip):$(kubectl get svc/hello-k8s -o jsonpath={.spec.ports[0].nodePort})

Replication

Scale up the hello-k8s deployment to 3 replicas:

kubectl scale deploy/hello-k8s --replicas=3

This action should set spec.replicas to 3

List pods to verify:

kubectl get po

AutoRecovery

Watch for changes to pod resources:

kubectl get pods --watch

In another terminal, delete several pods by id:

kubectl delete pod $(kubectl get pods | grep ^hello-k8s | cut -f1 -s -d' ' | head -n 2 | tr '\n' ' ')

What happened? How many pods remain?

kubectl get pods

Rollouts

Update your deployment's image spec to rollout a new release:

kubectl set image deploy/hello-k8s hello-k8s=jkleinert/nodejsint-workshop:v1

View the current state of your deployment

curl $(minishift ip):$(kubectl get svc/hello-k8s -o jsonpath={.spec.ports[0].nodePort})

Ask the API to list replicaSets

kubectl get rs

Rollbacks

View the list of previous rollouts:

kubectl rollout history deploy/hello-k8s

Rollback to the previous state:

kubectl rollout undo deployment hello-k8s

Build

Build and deploy container images

Web-based Create Workflow

Container Status

Source to Image

Combines source repos and operationally-maintained builder images to produce application images

Available as a standalone project (for use with Jenkins or other externalized build systems): github.com/openshift/source-to-image

Automate

git push to deploy

WebHook Build Automation

Iterate

Iterate using a fully containerized toolchain

Live Development

Make a minor edit to your local repo's index.html file,

export PODNAME=$(oc get pods -l app=http-base | tail -n 1 | cut -f1 -d' ')
oc rsync -w --exclude='.git,node_modules' . $PODNAME:

Collaborate

Share and replicate your success

Service Catalog & Brokers

Expose and provision services

www.openservicebrokerapi.org

Templates as Installers

oc create -f template.json

oc new-app -f template.json

Multi-Service App Example

Nodejs and MongoDB multi-service application example:

oc create -f https://raw.githubusercontent.com/openshift-roadshow/nationalparks-js/master/nationalparks-js.json

github.com/ryanj/nationalparks-js

Review and install the above template content using oc create, then try launching it via the web-based Service Catalog.

oc get all

API Resources

More Information

• Kubernetes Sources and Official Releases:
  http://github.com/kubernetes/kubernetes
• Kubernetes Docs: http://kubernetes.io/docs/home/
• OpenShift Sources and Official Releases:
  http://github.com/openshift/origin/
• OpenShift Docs: https://docs.openshift.com/

Free O'Reilly Ebook

Deploying to OpenShift
www.openshift.com/deploying-to-openshift

learn.openshift.com

Free-access Kubernetes and OpenShift learning portal, available in your browser

OpenShift 4 Developer Preview

try.openshift.com