DevOps Classroomnotes 17/Sep/2023

Kubernetes Contd

ConfigMaps and Secrets

• Refer Here for official docs of config maps
• They are used to store non credential information and make it available to Container in Pod as
  • Environmental Variable
  • Volume mounted to some folder
    
• Secrets in kuberenetes are exactly the same but the differenc is values in secrets should be base64 encode Refer Here for official docs
• Lets create a simple pod spec which mounts
  • username from config map
  • password from secret
• Refer Here for the changeset and apply the specs and View the environmental variables
  
• Refer Here for the changes with volumemounts for configu maps and secrets. Apply the changes to mount config map and secrets as volume
  

Kubernetes Volumes

• Refer Here for official docs
• Types of Volumes
  • Volumes: These are ephemeral
  • PersistentVolumes: Refer Here for Persistent Volume
• Kubernetes Storage Classes Refer Here
• For PVC, PVs and Storage classes refer class room recording
• Apply the manifests
  
• Refer Here for the changes to create a pvc on aks cluster
• Insert some data
• Delete the pod
• Recreate the pod
• Data should be present

Lens

• Refer Here for lens download

Elastic Kubernetes Service

• This is managed service from AWS
• EKS is easily created from a tool called as eksctl
• Install aws cli and configure authentication for aws iam user
• Lets create a config file ekscluster.yaml

apiVersion: eksctl.io/v1alpha5
kind: ClusterConfig

metadata:
  name: qteks-cluster
  region: us-east-1

nodeGroups:
  - name: ng-1
    instanceType: t2.large
    desiredCapacity: 2

• Now create the cluster by executing eksctl create cluster -f ekscluster.yaml
  
  

Exercise

Storage Class

• Refer Here for manifests and try creating storage classs and use it in mysql-pod
• Refer Here for creating table with some data in mysql

Setup application

• Create a nginx-db pod with a persistent volume (deployment with 1 replica)
• create a service nginx-svc with cluster ip
• Create a nginx-app pod (deployment with 1 replica)
• create a service nginx-app-svc with type LoadBalancer
• Access the load Balancer and configure the application
  

Article

• Refer Here

Daemonsets

• Refer Here for official docs
  

Assigning Pods to Nodes

• Refer Here
• Pods selection nodes
  
• nodes repelling pods: taints and tolerations

Stateful Set

• Refer Here for official docs
• Refer Here for running a stateful application
• Apply the Stateful set
  
  
• Now send a curl request to a pod by using <podname>.<svcname>