Intro to Kubernetes 2021-04-22 Shuuji Takahashi 

Today’s Goals ● Understand the overview of Kubernetes ● Know basic Kubernetes objects: Node, Pod, Deploy, Service ● Three simple Hands-on: ○ 1) create kubernetes cluster, 2) create Pod, 3) Deployment 4) publish Deployment using Service ● misc. 

What is Kubernetes What is Kubernetes? | Kubernetes - https://kubernetes.io/docs/concepts/overview/what-is-kubernetes/ 

What is Kubernetes ● Container orchestration system created by Google and released on 2014 ○ Google uses Borg (Kubernetes ancestor) internally since 2003 ○ Google deploys billions of containers every week ● Kubernetes run containerized applications in the cluster ● Features: ○ Automated rollouts and rollbacks ○ Self-healing ○ Horizontal scaling ○ etc. Kubernetes - https://kubernetes.io/ 

Kubernetes architecture 

Basic Kubernetes objects ● Node: represents single master/worker nodes ● Pod: a minimum manage unit in the Kubernetes cluster ● Deployment: manages one or more Pods across the Kubernetes cluster ● Service: expose/publish the Deployment 

Node ● Node represents single master/worker nodes ● 4 Nodes in the diagram ○ 1 control-plane Node ○ 3 worker Nodes ● Node hold information about each node ○ CPU, memory, GPU, etc. 

Play with Kubernetes ● Play with Kubernetes https://labs.play-with-k8s.com/ ● You can create a temporary Kubernetes cluster for learning ● Expires at 4 hours later ● Similar service: ○ Kubernetes Playground | Katacoda https://www.katacoda.com/courses/kub ernetes/playground 

Hands-on 1: Create Kubernetes cluster Let’s create a Kubernetes cluster 1. Setup control-plane node [node1 ~]$ kubeadm init --apiserver-advertise-address $(hostname -i) --pod-network-cidr 10.5.0.0/16Take a note 2. Take a note of `kubeadm join` command (don’t copy below; token will be changed every time): [node1 ~]$ kubeadm join 192.168.0.8:6443 --token 800kr4.o240gue4k0k72zcj \ --discovery-token-ca-cert-hash sha256:6caacab32dc51e28fcd006231d547c5e2e3f39ed96626a80d39801345d196311 

Hands-on 1: Create Kubernetes cluster 3. Initialize cluster networking (for “Play with Kubernetes”) [node1 ~]$ kubectl apply -f https://raw.githubusercontent.com/cloudnativelabs/kube-router/master/daemonset/kub eadm-kuberouter.yaml 4. Add worker nodes [node2 ~]$ kubeadm join 192.168.0.8:6443 --token 800kr4.o240gue4k0k72zcj \ --discovery-token-ca-cert-hash sha256:6caacab32dc51e28fcd006231d547c5e2e3f39ed96626a80d39801345d196311 

Hands-on 1: Create Kubernetes cluster 5. Check Nodes status # Get a node list [node1 ~]$ kubectl get node NAME STATUS ROLES AGE VERSION node1 Ready control-plane,master 22m v1.20.1 node2 Ready 21m v1.20.1 # Show the detail information [node1 ~]$ kubectl describe node/node1 ... 

Pod ● Pod is a minimum manage unit in the Kubernetes cluster ● Contains one (or more) container inside a Pod ● Run application process in the container ● For example: ○ Nginx container ○ PostgreSQL container ○ Containerized API server application ○ etc. Nginx container 

Hands-on 2: Create Pod ● Create a Pod template YAML file for webserver Pod running nginx container [node1 ~]$ kubectl run webserver --image=nginx --dry-run=client -o=yaml > webserver-pod.yaml [node1 ~]$ cat webserver-pod.yaml apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: webserver name: webserver spec: containers: - image: nginx name: webserver resources: {} dnsPolicy: ClusterFirst restartPolicy: Always status: {} 

Hands-on 2: Create Pod # Create a Pod [node1 ~]$ k apply -f nginx-pod.yaml pod/nginx created # Check the Pod [node1 ~]$ kubectl get pod NAME READY STATUS RESTARTS AGE nginx 1/1 Running 0 37m # Where is the Pod [node1 ~]$ kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES nginx 1/1 Running 0 34m 10.5.1.4 node2 

Deployment ● Deployment manages one or more Pods across the Kubernetes cluster ● Can keep the number of replicas (auto-recovery) ● Rolling update Nginx Nginx Nginx 

● Deployment creates and updates Pods across the Kubernetes cluster (via ReplicaSet object) ● Can keep the number of replicas (auto-recovery) ● Realize rolling update Deployment Nginx Nginx Nginx 

Hands-on 3: Create Deployment ● Create a Deployment template YAML file for web Deployment running nginx container [node1 ~]$ kubectl create deployment web --image=nginx:latest --dry-run=client -o=yaml > web-deploy.yaml [node1 ~]$ cat web-deploy.yaml apiVersion: apps/v1 kind: Deployment metadata: creationTimestamp: null labels: app: webserver name: webserver (cont’d) spec: replicas: 1 selector: matchLabels: app: webserver strategy: {} template: metadata: creationTimestamp: null labels: app: webserver spec: containers: - image: nginx:latest name: nginx resources: {} status: {} 

Hands-on 3: Create Deployment # Create a Deployment [node1 ~]$ k apply -f web-deploy.yaml deployment.apps/web created # Check the Deployment and Pod created [node1 ~]$ k get deploy,pod -o wide NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR deployment.apps/web 1/1 1 1 96s nginx nginx:latest app=web NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES pod/web-86cd4d65b9-fjbgr 1/1 Running 0 96s 10.5.1.6 node2 

Hands-on 3: Create Deployment # Access webserver [node1 ~]$ curl 10.5.1.6 --head HTTP/1.1 200 OK Server: nginx/1.19.10 Date: Wed, 21 Apr 2021 16:24:56 GMT Content-Type: text/html Content-Length: 612 Last-Modified: Tue, 13 Apr 2021 15:13:59 GMT Connection: keep-alive ETag: "6075b537-264" Accept-Ranges: bytes 

Hands-on 3: Create Deployment # Scale up and version down experiments [node1 ~]$ vi web-deploy.yaml [node1 ~]$ kubectl diff -f web-deploy.yaml diff -u -N /tmp/LIVE-407848292/apps.v1.Deployment.default.web /tmp/MERGED-110938483/apps.v1.Deployment.default.w eb --- /tmp/LIVE-407848292/apps.v1.Deployment.default.web 2021-04-21 16:27:07.372300600 +0000 +++ /tmp/MERGED-110938483/apps.v1.Deployment.default.w eb 2021-04-21 16:27:07.384300629+0000 @@ -6,7 +6,7 @@ (...) creationTimestamp: "2021-04-21T16:22:35Z" - generation: 1 + generation: 2 Labels: app: web managedFields: @@ -93,7 +93,7 @@ uid: ac702c97-db70-4322-9af5-589327b084c6 spec: progressDeadlineSeconds: 600 - replicas: 1 + replicas: 5 revisionHistoryLimit: 10 @@ -110,7 +110,7 @@ spec: containers: - - image: nginx:latest + - image: nginx:1.18 imagePullPolicy: Always name: nginx 

Hands-on 3: Create Deployment # apply and watch [node1 ~]$ kubectl apply -f web-deploy.yaml; watch kubectl get deploy,pod -o wide NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR deployment.apps/web 5/5 5 5 24m nginx nginx:1.18 app=web NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES pod/web-7989784f96-7dhts 1/1 Running 0 15m 10.5.1.11 node2 pod/web-7989784f96-g4s2c 1/1 Running 0 12s 10.5.1.51 node2 pod/web-7989784f96-mct2n 1/1 Running 0 15m 10.5.1.10 node2 pod/web-7989784f96-mpm2t 1/1 Running 0 15m 10.5.1.9 node2 pod/web-7989784f96-p87rx 1/1 Running 0 15m 10.5.1.16 node2 

Hands-on 3: Create Deployment # Access webserver [node1 ~]$ curl 10.5.1.1 --head HTTP/1.1 200 OK Server: nginx/1.18.0 Date: Wed, 21 Apr 2021 16:48:18 GMT Content-Type: text/html Content-Length: 612 Last-Modified: Tue, 21 Apr 2020 14:09:01 GMT Connection: keep-alive ETag: "5e9efe7d-264" Accept-Ranges: bytes 

Hands-on 3: Create Deployment # Delete Pod intentionally [node1 ~]$ kubectl delete pod/ ... 

Service ● Service exposes / publishes the Deployment inside the cluster ● 

Other Kubernetes objects ● ConfigMap / Secret ● StatefulSet ● Persistent Volume / Persistent Volume Claim ● Service ● Ingress ● →Next time...? 

Kubernetes website ● Many information ○ Concepts, Tasks, Tutorials, References ● Website: https://k8s.io ● Maintained by Kubernetes community & developers at #sig-docs ● Japanese translation at #sig-docs-ja Kubernetes Website - https://kubernetes.io/ja/ 

GKE: Google Kubernetes Engine ● Full-managed Kubernetes cluster provided by Google Cloud ○ Control-plane is fully managed ● GKE Autopilot mode is introduced on February 2021 ○ Worker nodes are also fully managed Building the future with Google Kubernetes Engine | Google Cloud Blog https://cloud.google.com/blog/products/containers-kubernetes/building-t he-future-with-google-kubernetes-engine 

References ● Kubernetes Website - https://kubernetes.io/ ● Play with Kubernetes - https://labs.play-with-k8s.com/ ● Building the future with Google Kubernetes Engine | Google Cloud Blog - https://cloud.google.com/blog/products/containers-kubernetes/building-t he-future-with-google-kubernetes-engine ● Icon deck: icono-k8s-0.3 - Google Slides - https://docs.google.com/presentation/d/15h_MHjR2fzXIiGZniUdHok_FP0 7u1L8MAX5cN1r0j4U/edit#slide=id.g4cac41f932_1_94 

Deploy WordPress & MySQL with Persistent Volume ? Example: Deploying WordPress and MySQL with Persistent Volumes | Kubernetes - https://kubernetes.io/docs/tutorials/stateful-application/mysql-wordpress-per sistent-volume/