vaibhav.account – Best DevOps https://www.bestdevops.com Lets Learn, Do it & Share! Thats a Best DevOps!!! Wed, 06 Oct 2021 03:54:00 +0000 en-US hourly 1 https://wordpress.org/?v=7.1.2 Difference between kubectl exec and kubectl attach? https://www.bestdevops.com/difference-between-kubectl-exec-and-kubectl-attach/ Wed, 06 Oct 2021 03:53:58 +0000 https://www.bestdevops.com/?p=22097

kubectl attachkubectl exec
We can attach to the main process run by the container, which is not always bash. Which is the PID1. It allows us to execute any process within the container
Attach to the one running (no choice)Run any command you want to execute.

]]> How certifcate based auth works ? https://www.bestdevops.com/how-certifcate-based-auth-works/ Wed, 06 Oct 2021 03:46:43 +0000 https://www.bestdevops.com/?p=22094

We use PKI certificates for authentication over TLS in Kubernetes. If we install Kubernetes with “kubeadm” command, the certificates that your cluster requires are automatically generated. You can also generate our own certificates.

How Certificates are used in Kubernetes Cluster:

  • Client certificates for the kubelet to authenticate to the API server
  • Server certificate for the API server endpoint
  • Client certificates for administrators of the cluster to authenticate to the API server
  • Client certificates for the API server to talk to the kubelet
  • Client certificate for the API server to talk to etcd
  • Client certificate/kubeconfig for the controller manager to talk to the API server
  • Client certificate/kubeconfig for the scheduler to talk to the API server.

NOTE: If we install Kubernetes with kubeadm, certificates are stored in /etc/kubernetes/pki

]]> Kubernetes in Vaibhav’s Words !! https://www.bestdevops.com/kubernetes-in-vaibhavs-words/ Mon, 04 Oct 2021 10:15:27 +0000 https://www.bestdevops.com/?p=21986

What is Kubernetes?
— Launched by Google
— Part of CNCF
— Written in golang
— Kubernetes is a container orchestrator, and helps to manage containerized applications
— Helps in workload placement on different nodes
— Does infrastructure abstraction
— Maintains desired state.

Why Kubernetes?
— speed of deployment
— ability of absorb changes
— ability to recover quickly
— We can deploy a scalable solution using kubernetes
— hide complexity in the cluster

How Kubernetes works?
Components of Kubernetes:

kube-apiserver

— front-end to the control plane.
— expose the Rest API
— uses JSON format

CLuster Store

— Persistent storage cluster state and config
— uses etcd
— Distributed .. consistent .. watchable

kube-controller-manager

Controls different controllers:
— node controller
— endpoint controller
— namespace controller

Watchers the changes
Helps maintain desired state

Kube-scheduler

keep watching api-server
api-server assign work to scheduler.

Assignment of work to worker nodes
— affinity
— constraint
— resources

What is POD?
–- Compute unit
— running in worker node
— pod is instantiated not created by Kubelet
— Atomic unit of scheduling
— Pods cannot be re-deployed
— Contains one or more containers.
— Live till the container is live
— Lifecycle: pending –> running –> Failed / Succeed

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