Kubernetes Matthias Haeussler Mirna Alaisami Overview Overview - - PowerPoint PPT Presentation

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Kubernetes Matthias Haeussler Mirna Alaisami Overview Overview - - PowerPoint PPT Presentation

Dec 09, 2022 385 likes •922 views

Kubernetes Matthias Haeussler Mirna Alaisami Overview Overview Kubernetes is an open-source platform designed to automate deploying , scaling , and operating application containers . Kubernetes v1.0 was released in 2015. It utilizes

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Kubernetes

Matthias Haeussler Mirna Alaisami

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Overview

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Overview

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  • Kubernetes is an open-source platform

designed to automate deploying, scaling, and operating application containers.

  • Kubernetes v1.0 was released in 2015.
  • It utilizes the advantages of

Containerization, Continuous Integration/Delivery, DevOps, Cloud Computing and Microservices.

  • It provides much of the simplicity of

PaaS with the flexibility of IaaS, and enables portability across infrastructure providers.

  • Docker is the most common container

runtime used in K8s, but it also supports

  • ther runtimes.

[1]

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CaaS Concepts

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  • Provides a complete container environment for deploying and

managing containers, applications and clusters.

  • Container Orchestration lies at the heart of container

platforms.

  • Focus is on creating the app containers and maintaining them in

the future.

CaaS Concepts

5 [2]

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Developer Responsibility

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Developer Responsibility

7 Application Code

Data Store Runtime / Middleware Containers Virtualization Hardware

IaaS

Operating System Application Code Data Store Runtime / Middleware Containers Virtualization Hardware

CaaS

Operating System Application Code Data Store Runtime / Middleware Containers Virtualization Hardware

PaaS

Operating System Application Code Data Store Runtime / Middleware Containers Virtualization Hardware

FaaS

Operating System

K8s Cloud Native Platform Scope

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K8s Components

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K8s Componenets

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Master Node Worker Node Worker Node

A cluster is a logical unit, consisting of one Master node and 1..n Worker nodes.

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K8s Componenets

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Master Node Worker Node Worker Node

The Master Node is the server that is responsible for the Kubernetes management tasks.

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K8s Componenets

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Master Node Worker Node Worker Node

Worker Nodes are the worker machines and are managed by the master components.

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K8s Componenets

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Master Node Worker Node Worker Node

The scheduler's main responsibility is to place the containers on the workers according to various policies, metrics, and resource requirements.

Scheduler

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K8s Componenets

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Master Node Worker Node Worker Node

The controller manager is responsible for reconciling the state of the cluster with the desired state, as specified via the API.

Sheduler Controller-manager

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K8s Componenets

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Master Node Worker Node Worker Node

The API server exposes a highly-configurable REST interface to all of the Kubernetes resources.

Sheduler Controller-manager API

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K8s Componenets

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Master Node Worker Node Worker Node

The kubelet is responsible for communicating with the master services.

Sheduler Controller-manager API Kubelet Kubelet

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K8s Componenets

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Master Node Worker Node Worker Node

The Docker engine is the container host that creates and runs Docker containers.

Sheduler Controller-manager API Kubelet Kubelet Docker Docker

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K8s Componenets

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Master Node Worker Node Worker Node

The kube-proxy is in charge of managing network connectivity to the containers.

Sheduler Controller-manager API Kubelet Kubelet Docker Docker Kube-proxy Kube-proxy

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K8s Componenets

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Master Node Worker Node Worker Node

So, in k8s we can enforce what is called "Desired state management“, which means that I can feed the cluster services with specific configuration, and those services will run the configuration as desired in my infrastructure.

Sheduler Controller-manager API Kubelet Kubelet Docker Docker Kube-proxy Kube-proxy

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K8s Basics

Introduction (Usecase)

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K8s Componenets

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The desired state exists in the Deployment, which contains the configuration that you feed to the cluster.

Deployments Worker Node Worker Node

Kubelet Kubelet Docker Docker Kube-proxy Kube-proxy

Master Node

Sheduler Controller-manager API

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K8s Componenets

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The first fundamental piece inside this deployment is the Pod.

Deployments Pod1 Worker Node Worker Node

Kubelet Kubelet Docker Docker Kube-proxy Kube-proxy

Master Node

Sheduler Controller-manager API

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K8s Componenets

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Within a Pod, there can be one or more running Containers.

Deployments Pod1

  • ContImg1
  • ContImg2

Worker Node Worker Node

Kubelet Kubelet Docker Docker Kube-proxy Kube-proxy

Master Node

Sheduler Controller-manager API

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K8s Componenets

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In order to specify how many Pods will be run, a ReplicaSet needs to be defined.

Deployments Pod1

  • ContImg1
  • ContImg2

ReplicaSet -> 3 Worker Node Worker Node

Kubelet Kubelet Docker Docker Kube-proxy Kube-proxy

Master Node

Sheduler Controller-manager API

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K8s Componenets

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Deployments Pod1

  • ContImg1
  • ContImg2

ReplicaSet -> 3 Pod2

  • ContImg3

ReplicaSet -> 2

Let us define another Pod with 2 instances.

Worker Node Worker Node

Kubelet Kubelet Docker Docker Kube-proxy Kube-proxy

Master Node

Sheduler Controller-manager API

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K8s Componenets

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Worker Node Worker Node

Kubelet Kubelet Docker Docker Kube-proxy Kube-proxy

Master Node

Sheduler Controller-manager API

Deployment Pod1

  • ContImg1
  • ContImg2

ReplicaSet -> 3 Pod2

  • ContImg3

ReplicaSet -> 2

Taking the Deployment file and feeding it to the API, the master services will figure out how to schedule the pods on the workers, making sure that the specified number of instances is running.

Deployments Pod1

  • ContImg1
  • ContImg2

ReplicaSet -> 3 Pod2

  • ContImg3

ReplicaSet -> 2

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K8s Componenets

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Worker Node Worker Node

Kubelet Kubelet Docker Docker Kube-proxy Kube-proxy

Master Node

Sheduler Controller-manager API

Deployments Pod1

  • ContImg1
  • ContImg2

ReplicaSet -> 3 Pod2

  • ContImg3

ReplicaSet -> 2

P1R1 P1R2 P1R3

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K8s Componenets

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Worker Node Worker Node

Kubelet Kubelet Docker Docker Kube-proxy Kube-proxy

Master Node

Sheduler Controller-manager API

Deployments Pod1

  • ContImg1
  • ContImg2

ReplicaSet -> 3 Pod2

  • ContImg3

ReplicaSet -> 2

P1R1 P1R2 P1R3 P2R1 P2R2

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K8s Componenets

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Worker Node Worker Node

Kubelet Kubelet Docker Docker Kube-proxy Kube-proxy

Master Node

Sheduler Controller-manager API

Deployments Pod1

  • ContImg1
  • ContImg2

ReplicaSet -> 3 Pod2

  • ContImg3

ReplicaSet -> 2

P1R1 P1R2 P1R3 P2R1 P2R2

So, at any point in time, the master services are responsible for making sure that the fed configuration is running on the worker nodes.

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K8s Componenets

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Worker Node

Kubelet Docker Kube-proxy

Master Node

Sheduler Controller-manager API

Deployments Pod1

  • ContImg1
  • ContImg2

ReplicaSet -> 3 Pod2

  • ContImg3

ReplicaSet -> 2

P1R1 P1R2 P2R1

Worker Node

Kubelet Docker Kube-proxy P1R3 P2R2

What happens if one worker node is lost?!

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K8s Componenets

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Worker Node

Kubelet Docker Kube-proxy

Master Node

Sheduler Controller-manager API

Deployments Pod1

  • ContImg1
  • ContImg2

ReplicaSet -> 3 Pod2

  • ContImg3

ReplicaSet -> 2

P1R1 P1R2 P2R1

The kubelet services will notify us about the changes and the scheduler will instantiate the lost pods again to reach the desired state.

P1R3 P2R2

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K8s Basics

Pods

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  • A pod is an abstract layer which synthesizes a certain amount of

Docker containers that are meant to run together´.

  • It represents the smallest unit of deployment, i.e., a single

instance of an application in Kubernetes, which might consist of either a single container or a small number of containers that are tightly coupled.

  • Pods provide two kinds of shared resources for their constituent

containers: networking and storage.

  • Containers within a pod share the same IP address, port space,

hostname and storage, and can find each other via localhost.

K8s Basics: Pods

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runtime app runtime app

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K8s Basics

Deployments

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  • A deployment is a description of the desired condition of a

particular microservice (number of instances, port forwarding, docker image …)

  • ReplicaSets are (usually) combined with pods when defining the

deployment

  • A ReplicaSet ensures that a specified number of pod replicas are

running at any given time, thus ReplicaSets enable pods to scale horizontally

K8s Basics: Deployments

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runtime app runtime app

pod

replica set runtime app runtime app

pod v2

replica set v2 deployment

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K8s Basics

Services

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Apps - Deployment

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Apps – Deployment

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Dockerfile runtime app app runtime

base container

runtime app

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Apps – Deployment

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kubectl run

service/ingress

endpoint

runtime app runtime app

pod

replica set runtime app

pod v2

replica set v2 deployment runtime app

pod v2

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Apps – Deployment

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Run it locally on your machine „optional“ Push the image to a registry Deploy your app to the K8s Cluster Expose your app to the internet Scale your deployment manually Scale your deployment automatically Deploy a new version of your app „rolling update“ Package your app into a Docker image

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Apps – Deployment “Summary”

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todo Postgres UI postgres.yml todobackend.yml todoui.yml todobackend.service.yml postgres.service.yml todoui.service.yml

  • config.yml
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K8s cluster networking

Intra pod communication

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K8s Cluster Networking - Intra pod communication

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  • The containers in a Pod share the same IP address and port space, so

they can directly communicate with each other’s port on localhost.

  • There is no danger of port collision between different pods, since each

pod has its own IP address, and when a container in the pod uses localhost, it applies to the pod's IP address only.

Pod1 Pod2

IP: 10.10.10.1 IP: 10.10.10.2 Node

Port:1234 Port:1234 Port:8080 Localhost

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K8s cluster networking

Service ClusterIP

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  • Cross-node pod to pod communication.
  • The default Kubernetes ServiceType.
  • Gives you a service inside your cluster that other pods (apps)

inside your cluster can access.

  • However, there is no external access.

K8s Cluster Networking - Service ClusterIP

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Service

K8s Cluster

Pod2 Pod3 Pod1

Node1 Node2

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K8s cluster networking

Service NodePort

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  • Exposes the service with a public IP of Node and a static defined port

(NodePort).

  • Enables external traffic to get directly to the NodePort service, such that any

traffic that is sent to the static port is forwarded to the service.

K8s Cluster Networking - Service NodePort

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Service

K8s Cluster

Pod2 Pod3 Pod1 Traffic

Node1 Node2 Port: 30000 Port: 30000

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K8s cluster networking

Service LoadBalancer

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  • Exposes the service externally using a cloud provider’s load balancer.
  • NodePort and ClusterIP services, to which the external load balancer will

route, are automatically created.

K8s Cluster Networking - Service LoadBalancer

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Traffic LoadBalancer Service Pod2 Pod3 Pod1

Node1 Node2 K8s Cluster

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Sources

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Sources

1. https://i2.wp.com/thepracticalsysadmin.com/wp- content/uploads/2018/05/k8s1.png?ssl=1 2. https://www.slideshare.net/KarlIsenberg/container-

  • rchestration-wars-2017-edition

3. https://medium.com/@odedia/comparing-kubernetes-to-pivotal- cloud-foundry-a-developers-perspective-6d40a911f257 4. https://res.cloudinary.com/dukp6c7f7/image/upload/f_auto,fl_los sy,q_auto/s3-ghost/2016/06/o7leok.png 5. https://cdn-images- 1.medium.com/max/1200/1*NMYJ6pN61RsOwzQUDXgg1w.png, https://www.blablacar.com/

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Sources

6. https://www.01net.it/wp- content/uploads/sites/14/2016/04/Huawei-logo-2015.jpg, https://www-file.huawei.com/-/media/corporate/pdf/press- center/media-kit/huawei_fact_sheet_2015_en.pdf 7. https://www.signavio.com/wp-content/uploads/2013/03/Logo- Zalando-WEB1.png?w=480&h=160&zc=2, http://tech.eu/features/339/inside-zalando/ 8. https://istio.io/img/logo.png 9. https://cdn-images- 1.medium.com/max/1200/1*fWtVse6DItxvOBowU85Www.png

51

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Novatec Consulting GmbH

Dieselstraße 18/1 D-70771 Leinfelden-Echterdingen

  • T. +49 711 22040-700

info@novatec-gmbh.de www.novatec-gmbh.de

Senior Managing Consultant

Matthias Haeussler

matthias.haeussler@novatec-gmbh.de Consultant

Mirna Alaisami

Mirna.Alaisami@novatec-gmbh.de