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README.md

Table of Contents

Requirements

Scenario-103: 1-Node K8S Deployment III

  • Objective: Advanced k8s deployment for one single db service
  • Requirements:
1. Suppose your k8s/minikube have multiple cluster, how you can segrate them? (Hint: namespace)
2. When we initialize mysql via yaml, avoid store mysql root password in plain text. (Hint: secrets)
3. Make sure we can create no more than 1 pods for DB server. (Hint: ResourceQuota)

See kubernetes.yaml

Background & Highlights

  • What is StatefulSet? Why we need it?
  • ResourceQuota can apply to current namespace.

Procedure

Deployment

To setup mysql service, here we use mysql image in docker hub.

  • Start vm
# start a VM to host our deployment
minikube start

Here we have created a namespace of k8s-1node-test

# https://kubernetes.io/docs/tasks/administer-cluster/namespaces-walkthrough/
kubectl create namespace k8s-1node-test

Specify mysql root password via k8s secrets, instead of storing the plain text password in yaml directly.

kubectl --namespace k8s-1node-test create secret generic mysecret \
        --from-literal=mysql_root_password='my-secret-pw'

kubectl --namespace k8s-1node-test get secrets
kubectl --namespace k8s-1node-test describe secret mysecret

# ,----------- Example
# | macs-MacBook-Pro:Scenario-103 mac$ kubectl --namespace k8s-1node-test describe secret mysecret
# | Name:         mysecret
# | Namespace:    k8s-1node-test
# | Labels:       <none>
# | Annotations:  <none>
# | 
# | Type:  Opaque
# | 
# | Data
# | ====
# | mysql_root_password:  12 bytes
# `-----------

# Create resourcequota
kubectl --namespace k8s-1node-test create -f ./resourcequota.yaml
kubectl --namespace k8s-1node-test --namespace=k8s-1node-test get resourcequota

# Create k8s volume, deployment and service
kubectl --namespace k8s-1node-test create -f ./kubernetes.yaml --validate=false

See kubernetes.yaml

Verify Deployment

  • Check k8s web UI Dashboard
minikube dashboard
  • List k8s resources
# list deployments
kubectl --namespace k8s-1node-test get deployment

# list service
kubectl --namespace k8s-1node-test get services

# List ResourceQuota
kubectl --namespace k8s-1node-test --namespace=k8s-1node-test get resourcequota

# list pods
kubectl --namespace k8s-1node-test get pods

# ,----------- Example
# | macs-MacBook-Pro:Scenario-103 mac$ kubectl --namespace k8s-1node-test get pods
# | NAME                                   READY     STATUS    RESTARTS   AGE
# | dbclient-deployment-69844df475-nwkvg   1/1       Running   0          3m
# | dbclient-deployment-69844df475-vp2g2   1/1       Running   0          3m
# | dbserver-deployment-6d9bdbfbf4-9x7nv   1/1       Running   0          3m
# `-----------
  • Run functional test

Open mysql client to access the mysql server

Use phpmyadmin, create a database and a table

Find endpoint of phpmyadmin and dbserver

minikube service list

# ,----------- Example
# | macs-MacBook-Pro:Scenario-103 mac$ minikube service list
# | |----------------|----------------------|-----------------------------|
# | |   NAMESPACE    |         NAME         |             URL             |
# | |----------------|----------------------|-----------------------------|
# | | default        | kubernetes           | No node port                |
# | | k8s-1node-test | my-dbclient-service  | http://192.168.99.103:32452 |
# | | k8s-1node-test | my-dbserver-service  | http://192.168.99.103:31049 |
# | | kube-system    | heapster             | No node port                |
# | | kube-system    | kube-dns             | No node port                |
# `-----------

TODO: remove http, add screenshot

  • Mysql server resilient test
  • If one instance is down, another will be started automatcially.

TODO

From Web UI, delete the mysql server Pod.

We should see ReplicationController will start a new one.

Confirm the database and table still persist, which were created in last step.

Cleanup

  • Delete k8s resources
kubectl --namespace k8s-1node-test delete -f ./kubernetes.yaml
kubectl --namespace k8s-1node-test delete -f ./resourcequota.yaml
  • Delete namespace
kubectl delete namespace k8s-1node-test
  • Destroy env
minikube delete

Highlights

  • Q: How does the volume process work?

  • Q: How PersistentVolumeClaim know use which PersistentVolume?

More resources