CKA 5: Application Life Cycle Management


Init Containers

initContainers: 
It is a list
Each init container run, one at a time in sequential order. 
It is like job. Run to complete
If any one fails then pod will be restarted, unless pod has restartPolicy = Never
The init container does not support 
- lifecycle, 
- livenessProbe, 
- readinessProbe, 
- startupProbe

Pod-> activeDeadlineSeconds  and pod->container->liveness probe , prevents init containers from restarting from ever. 

Resources

Highest value among all init containers is considered for resources->request and resources->limit

For pod effective limit for resources->request and resources->limit = Highest ( Highest (init containers) , summation ( all normal containers) ) 

This effect limit is considered to schedule a pod

The resources reserved by init container(s) is not used once they are completed,  by other containers. 

If we change image of container then only that container is restarted. If we change image of init container then whole pod is restarted.

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