DevOps Classroom Series – 22/Nov/2020

K8s Jobs and CronJobs

• Lets assume you want to run a Pod which runs a task and then terminates gracefully, To solve these kind of Problems k8s has Jobs & CronJobs
• The difference b/w k8s job & CronJob is CronJobs can be scheduled to run on a particular time frame
• Run the job as mentioned in the changeset Refer Here

K8s Ingress

• Ingress is an object in k8s that is used manage external access to services in the k8s cluster. Ingress provides layer 7 load balancing, so it will be aware of url’s
• Refer Here

Scenario:

• I have a application component which is running in a pod
• I have a database pod
• Application Pod is configured to scale automatically
• Now application pod needs to access db
• Approach 1:
  • Create a service for db
  • Whenever you add a service an environmental variables will be added in all pods containing svc ip and port
• Approach 2:
  • Use a Config Map. Config Map is a k8s object allows us to defined the application-related data.
  • Config maps are key value pairs
  • You can create config maps from
    • literal value
    • file
    • directory
  • Lets create a sample config map

  kubectl create configmap demovalue-map --from-literal=db-ip=10.0.83.222 
  

  
• In K8s we also have secret which are much like config maps but they can store secret of size 1kb in base 64 encoded form

Package Manager for k8s : Helm

• Helm is a Package manager for k8s
• Helm charts represent a k8s package
• Installing helm Refer Here
• Lets execute an example using helm in AKS Refer Here
• In k8s we write yaml manifests, helm simplifies and makes manfiests reusable
• Refer Here
• Journey of App from docker to k8s Refer Here