Debug School: Namrata

Day 3 Kubernetes Namrata

Namrata — Wed, 18 Oct 2023 12:06:49 +0000

Deamonset
Job
CronJob
ConfigMap
Service
Ingress

Day 2-Namrata

Namrata — Tue, 17 Oct 2023 11:49:38 +0000

Namespace
Pod
Replication Controller
Deployment

Namespace is for isolation and management of kubernets resources.
kubectl get namespaces

Pod:
Troubleshooting of pods
attach
port-forward
exec
kubectl auth can-i create pod

Replication Controller
Scale 1 pod to many controller

apiVersion: v1
kind: ReplicationController
metadata:
name: rajeshrc
spec:
replicas: 5
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: scmgalaxy/nginx-devopsschoolv1

Deployment

replication
rollout
controlling
rollback

What is Pod day 1 - Namrata

Namrata — Mon, 16 Oct 2023 11:49:18 +0000

Pod is the smallest atomic unit.
Pod contains containers
IP Address is giving to POD
IP Address is not given to containers.
A pod may have more than 1 container and IP address will be same.

We send a desire to apiserver which then instantiates pod

Pods are not created , but instantiated.
Static pods cannot be deleted.
Static pods are instantiated by kubelet directly without help of api server.

One pod can contain 2 containers , each container will have its IP address and a different port.

When many pods are connected , data is shared using Pod Network.

If there are 2 containers in pod , they talk to each other using localhost.

How do you define pods ?
api server: v1
Kind: pOD
metadata

No pods are every "redeployed"
Its a unit of scheduling

The Focus should be on :
learning 65 resources
YAML Files
HELM chart

Day 1 Kubernetes -Namrata

Namrata — Mon, 16 Oct 2023 07:17:05 +0000

1) What is Kubernetes?
Answer: It is a container orchestration tool. For VM many options are there like AWS , Azure , GCP , but for containers there is only 1 option which is kubernetes, primarily to Compute, Storage , Load balancing , security , DB, DNS and Security.

2) Why do we need Kubernetes ?
How to run containers at production level is the challenge.
Docker can manage single host , containers brings scalability challenges. One stop solution for scalability , self-healing ,recovery , networking etc.

3) How Kubernetes work ?

Kubernetes run in worker node and inside that it's a pod.
Master node manages worker nodes .Master controls the worker nodes .The Master is Linux whereas worker can be linux/windows.

4) Kubernetes Architecture ?

API server is the ears , it hears the instructions and send it to the Cluster Store which is like brain and controller keeps a watch just like eyes and scheduler is like mouth which assigns the work to minions.

5) Explain each component

1) Master Node : Manages worker node .We need 4 s/w components
a) api-server :Is bascially registry or a frontend to control pane.
b) Cluster-store: It is SOT . Like how you have DB so is its job.
c) kube-controller-manager : If node is up or down , pod is up pr down and watched for changes .It runs continously.
d) kube-scheduler: Assigns work to worker nodes.

via kubectl we send desire to kubernetes which firstly hits API server and then further processing happens.
Kubectl runs in each worker and bugs API server continously.
e) Pod - Is a logical entity , Container consumes RAM and CPU and not containers . Pod wraps the container.

Pods are instantiated , Containers are created.You cannot go inside pods and see logs , but with containers yes.
f) kube-proxy : Assigns IP Address to Pods and not to containers via IP tables . 4 container in a pod will have same IP Address.

Note:
1) All Nodes can communicate with All Pods
2) All Pods can communicate with each other on all nodes
3) API server is the only source of communication

All we need to do is setup cluster , and via kubectl send desire to kubernets , rest is all managed by it.

What is Kubernetes-Namrata

Namrata — Mon, 16 Oct 2023 06:47:50 +0000