AJ - intro to k8s

Question 1

Name 3 container runtimes

Answer 1

runC, containerd (usered by Docker), rkt

Question 2

3 components of worker node

Answer 2

container runtime, kubelet, kubeproxy

Question 3

3 components of master node

Answer 3

api-server, scheduler, controller

Question 4

What is the role of kubelet?

Answer 4

agent on worker node which communicates with master node

Question 5

what are two services run by container runtime?

Answer 5

ImageService and ContainerService

Question 6

What is the role of kube-proxy?

Answer 6

kube-proxy is the network proxy which runs on each worker node and listens to the API server for each Service endpoint creation/deletion. For each Service endpoint, kube-proxy sets up the routes so that it can reach to it

Question 7

Describe the 4 types of kubenetes set

Answer 7

All-in-One Single-Node Installation
With all-in-one, all the master and worker components are installed on a single node. This is very useful for learning, development, and testing. This type should not be used in production. Minikube is one such example, and we are going to explore it in future chapters.

Single-Node etcd, Single-Master, and Multi-Worker Installation
In this setup, we have a single master node, which also runs a single-node etcd instance. Multiple worker nodes are connected to the master node.

Single-Node etcd, Multi-Master, and Multi-Worker Installation
In this setup, we have multiple master nodes, which work in an HA mode, but we have a single-node etcd instance. Multiple worker nodes are connected to the master nodes.

Multi-Node etcd, Multi-Master, and Multi-Worker Installation
In this mode, etcd is configured in a clustered mode, outside the Kubernetes cluster, and the nodes connect to it. The master nodes are all configured in an HA mode, connecting to multiple worker nodes. This is the most advanced and recommended production setup.

Question 8

Kubernetes administration tools

Answer 8

kubeadm, kubespray, Kops

Question 9

What is purpose of ReplicationControllers

Answer 9

Ensure specified number of replicas are running.

Question 10

What is ReplicatSet

Answer 10

Same as ReplicationController which support both equality and set-based selectors