Debug School: rijil

Assignment - day3

rijil — Wed, 19 Oct 2022 09:20:00 +0000

What is POD? 5 Characteristics of pod
Pod is the most basic unit for scheduling in Kubernetes.
It contains one or more containers.
It is ephemeral.
Has its own IP
Pods share all kernel resources

What is Deployment and each feature of it with 1 example
Deployment is a method of creating pods with applications and ensuring that the desired number of pods(replicas) is always running on the cluster.
Replication + Controller + Versioning + Rollout + Rollback

What is Services and types of Services?
A k8s service is a Network LoadBalancer.
If you want to Load balance Pod by a Service, the label of the Service and the POD should match.
Types:
1) Node Port
2) Load balancer (Ex - AWS LB)

K8s Architecture and Components

rijil — Tue, 18 Oct 2022 06:36:00 +0000

Kubernetes Architecture:

A k8s cluster consists of master and worker nodes.
Master nodes manages the entire cluster.
Worker nodes is where the workloads(pods) run.Each node can contain 1 or more Pods. Each pod contains one or more containers.

Master Node:

Also called control plane. Will always be a linux box.
Inorder to setup master we need 4 main softwares installed.
1) API server :
This is the front end to the k8s cluster using which users interact with the cluster. Exposes REST API. Takes input in the form of json etc.

2) Cluster Store:
Persistent storage for cluster powered by ETCD. It is like the database for the cluster always maintaining the cluster state and configs

3) Controller Manager:
Watches for changes abd helps maintain the desired state

4) kube-scheduler:
Watches apiserver for new pods. Assigns pod sceduling to nodes.

Worker Node:

Also called minions or just nodes.
Has 3 main componenets
1) kubelet:
This is the k8s agent which is an exe running on each node.
Responsible for registring node with cluster by comunicating with API server

2) Container Engine - example Docker,Rocket,containerd
Responsible for container management

3) kube-proxy:
Responsible for k8s networking. Assings IP to pods, load balances across pods

Assignment - Day2

rijil — Tue, 18 Oct 2022 04:43:06 +0000

Kubernetes can manage multiple docker hosts (running several containers) reducing scalability issues
Can fix networking issues
Auto healing of Docker host by bringing the containers at a desired state
k8s views the data center as one computer
Load balancing services
Fast deployment
Container orchestrator
Micro service orchestration
Takes care of workload(container) placement
Resource allocation
Rollbacks
Ability to absorb changes quickly and recover quickly
Monitoring container health

Assignment

rijil — Mon, 17 Oct 2022 07:54:11 +0000

Docker stop vs kill
docker stop attempts to gracefully shutdown container(s) while docker kill immediately stops/terminates them;
docker stop issues a SIGTERM signal to the main process inside the container, while docker kill issues a SIGKILL signal;

Docker pause vs unpause
The docker pause command suspends all processes in the specified containers
The docker unpause command un-suspends all processes in the specified containers