Controllers in K8s
- Controllers are k8s objects which run other k8s resources. This k8s resource will be part of specification generally in template section.
- Controllers maintain desired state.
- Some of the controllers are
- Replication Controller/Replica Set
- Stateful Sets
- Deployments
- Jobs
- Cron Jobs
- Daemonset
K8s Jobs
- Refer Here for official docs
- K8s has two types of jobs
- Job: Run an activity/script to completion
- CronJob: Run an activity/script to completion at specific time period or intervals.
- Refer Here for the manifests with job and cronjob
- For jobs restartPolicy cannot be Always as job will never finish
- Jobs have backoffLimit to limit number of restarts and activeDeadline seconds to limit timeperiod of execution.
- Running job and waiting for completion
- Cronjob manifest which we have written create a job every minute and waits for completion
Lets go back to Pods
- Lets run a alpine pod
- Now if we want to execute a command in the container of alpine pod
- To access the terminal
- Exercise: If we have a pod with 2 container how exec a command on a specific container
- Lets run a pod which run application on some port
- Now if we want to access the application in container we can do port-forward (not recommended approach)
