Kubernetes Objects Flashcards
What is Replication Controller responsible for?
Maintaining a stable set of replica pods running at any given time.
Ensuring that the specified number of replicas is always up, ready, and healthy.
Can be used to increase or decrease the number of running pods.
What is Replication Controller denoted?
RC
What is a ReplicaSet
Next generation of Replication Controller
What is the desired state?
It is what you want your cluster’s workload to look like; it is the spec defined in the manifest file of the deployment.
What is the actual state and where is it held?
It represents the current state of any Kubernetes object.
It is held in the etcd.
What is a Deployment
A Kubernetes object that controls deploying and maintaining a set of pods.
Features of Deployment
Uses a ReplicaSet to keep the pods running.
Supports rolling updates and rollbacks; rollouts can be paused.
Keeps history of past deployments and allows the administrator to easily roll back to previous deployments.
Provides high-level abstraction.
Offers sophisticated logic for deploying, updating, and scaling a set of pods within a cluster.
What’s the difference between a ReplicaSet and a ReplicaController
A ReplicaSet uses set-based selectors which gives it more abilities. A RS is also used by deployments
A RC uses equality-based selectors
Are replica sets meant to be created on their own?
No, they are meant to be automatically created when deployments are created.
How many ports does a ClusterIP Service require?
2 ports. Port and TargetPort. It does not allow external access
State Available
Replicas that are available to users
State Current
Replicas that are current running
State Desired
The desired number of replicas of the application
Up-to-Date state
The replicas that have been updated (scaled up or down) to achieve the desired state
What is a Service?
It is a layer of abstraction on top of pods — usually based on labels and selectors — that provides network connectivity to pods in a given cluster.