Working with Kubernetes Flashcards
Type of workload objects
ReplicaSet
Deployment
StatefulSet
DaemonSet
Job
CronJob
ReplicaSet
A controller object that ensures a desired number of pods is running at any given time. ReplicaSets can be used to scale out applications and improve their availability. They do this by starting multiple copies of a pod definition.
Deployment
A Deployment can be used to describe the complete application lifecycle, they do this by managing multiple ReplicaSets that get updated when the application is changed by providing a new container image, for example. Deployments are perfect to run stateless applications in Kubernetes.
StatefulSet
Considered a bad practice for a long time, StatefulSets can be used to run stateful applications like databases on Kubernetes. Stateful applications have special requirements that don’t fit the ephemeral nature of pods and containers. In contrast to Deployments, StatefulSets try to retain IP addresses of pods and give them a stable name, persistent storage and more graceful handling of scaling and updates.
DaemonSet
Ensures that a copy of a Pod runs on all (or some) nodes of your cluster. DaemonSets are perfect to run infrastructure-related workload, for example monitoring or logging tools.
Jobs
Creates one or more Pods that execute a task and terminate afterwards. Job objects are perfect to run one-shot scripts like database migrations or administrative tasks.
CronJob
CronJobs add a time-based configuration to jobs. This allows running Jobs periodically, for example doing a backup job every night at 4am.
describes a unit of one or more containers that share an isolation layer of namespaces and cgroups.
Pod
Why the pod concept was introduced
to allow running a combination of multiple processes that are interdependent
Do containers in Pod share namespaces?
Yes
