1. About K8S health check Health check is the important feature of the k8s orchestrating. K8s can monitor those containers and automatically restart them if they fail. If the container’s main process crashes, the k8s will restart the container. Also if your application has a bug that causes it to crash every once in a while, k8s will restart it automatically.There are two kinds of ways for health check. Liveness and Readiness.

1. How to write the YAML 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 apiVersion: apps/v1 kind: Deployment metadata: name: nginx-deploymnet spec: replicas: 3 selector: matchLabels: app: web_server template: metadata: labels: app: web_server spec: containers: - name: nginx image: nginx:1.7.9 Okay, Let us analysis this YAML sample. It used the indentation to represent the layer. Every layer was dependent and called each other.

A Deployment provides declarative updates for Pods and ReplicaSets. We can make use of many Deployment features. This chapter covers Updating a Deployment, rolling back a Deployment, Scalling a Deployment, Pausing and Resuming a Deployment and Deployment Status. First, we create a Deployment. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 apiVersion: apps/v1 kind: Deployment metadata: name: nginx-deploymnet spec: replicas: 3 selector: matchLabels: app: web_server template: metadata: labels: app: web_server spec: containers: - name: nginx image: nginx:1.

1. emptyDir It’s the basis of Volume. The life cycle depends on the Pod. The volume will be removed when the related Pod was removed. So we can think of it as the path of the Pod. All the containers of the pod share this voiume. Let’s show how to setup the volume configure. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 apiVersion: v1 kind: Pod metadata: name: producer-consumer spec: containers: - image: busybox name: producer volumeMounts: - mountPath: /producer_dir name: shared-volume args: - /bin/sh - -c - echo "hello world" > /producer_dir/hello; sleep 30000 - image: busybox name: consumer volumeMounts: - mountPath: /consumer_dir name: shared-volume args: - /bin/sh - -c - cat /consumer_dir/hello; sleep 30000 volumes: - name: shared-volume emptyDir: {} The above file is about configure the volume practice.

1. k8s components architecture. Okay, it’s very easy to understand. Like above, master node is the most important. It controls the other nodes to join the cluster. Also API server is exposed outside. Through the master node, then can arrange the other nodes. 2. Practice Target: Create the k8s cluster, then deploy the application to these 2 nodes. Steps. Use kubeadm init to create the master k8s cluster, then join node1 and node2 to the cluster.

1. Several ways to upgrade Let’s look at a case first, how to deal with this situation: The POD is currently using the V1 version, and now there is a V2 version, how to replace the V2 version with the V1 version? There are three ways: Delete the old version POD and replace it with the new version POD This method is more violent. It is to directly modify the configuration template of V1 to V2, and then delete the POD of V1.