DevOps Classroom notes 28/Jan/2024

K8s contd

Exercise- Replicaset

• create a replicaset with pod spec running alpine container without any args
  
• I want to create a replicaset with nginx and want to access them from browser

Service

• Refer Here for official docs

Trail 1:

• Create a service to forward the request to 80 port of nginx pods with label app:nginx
• Refer Here for the manifest
  
• Access the svc as discussed in the class

Trail 2:

• Create a replica set with 3 httpd pods
• create a service with some matching labels
• Refer Here for the changes and apply manifests
  
• When we create a service, service creates endpoint which all the ip-addresses of matching pods
  
• If we want to access the svc from outside or use node-network we have two options
  • temporary: kubectl port-forward
  • continued access: for this we need to understand service types in k8s

Service Types

• k8s service is of 4 types Refer Here
  • cluster ip:
    • this gives private access with in k8s cluster
  • nodeport:
    • k8s service can be exposed on a specific port (30000-32767) on all nodes of k8s cluster
  • load balancer: This is used generally by managed k8s clusters (EKS, AKS), This creates a cloud load balancer
  • externalName:

Trail 2 Continued:

• Modify the service to expose the apache service on port 30000
• Refer Here for the changes
  
  

Trail3

• Create a replica set with spring petclinic image shaikkhajaibrahim/spcjan2024:1.0
  • This runs on 8080 port
  • Now create 3 replicas of this
  • label suggestions:
    • app: spc
    • env: dev
    • version: v3.4.0
• Create a service of type cluster ip
• expose this to the outside world on port 31000 using node port
• Refer Here for the manifests
  

Exercises

• figure out the purpose of /etc/resolve.conf