Intro to kubernetes
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The document provides an introduction to Kubernetes, an open-source platform for automating the deployment, scaling, and management of containerized applications, emphasizing its architecture and key features such as automatic binpacking and self-healing. It outlines essential building blocks like pods, services, replication controllers, and volumes, as well as deployment patterns like canary updates and rolling updates. The document concludes with resources for further exploration of Kubernetes and invites questions from the audience.
Intro to kubernetes
- 1. Intro to KubernetesMiloš Simić :: NS BigData Meetup
- 2. Plan • What is Kubernetes • Architecture • Building blocks • Where to go next • Questions http://www.businesscloudnews.com/2016/06/02/emc-launches-storage-provisioning- framework-for-containers/
- 3. What is Kubernetes • Kubernetes is an open-source system (written in Go) for automating deployment, scaling, and management of containerized applications • It groups containers that make up an application into logical units for easy management and discovery. • Kubernetes builds upon 15 years of experience of running production workloads at Google, combined with best ideas and practices from the community. • Inspired and informed by Google’s experiences and internal systems (Borg best name ever :D) • Supports multiple cloud and bare-metal environments • Supports multiple container runtimes https://www.joyent.com/triton/compute
- 4. What can Kubernetes do • Automatic binpacking • Horizontal auto-scaling • Automated rollouts and rollbacks • Self-healing • Application health checking • … • Manage applications, not machines http://www.businesscloudnews.com/2016/06/02/emc-launches-storage-provisioning- framework-for-containers/
- 5. We need a cluster • Laptop to multi-node cluster • Hosted or self managed • On-Premise or Cloud Bare • Physical or Virtual Machines • Or bunch of Raspberry PIs Raspberry pi kubernetes cluster
- 6. Architecture • etcd overall state of the cluster at any given point of time. • The Controllers create, update and delete the resources they manage (pods, service endpoints, etc.) • API server provides internal and external interface to Kubernetes. • Scheduler tracks resource utilization on each node to ensure that workload is not scheduled in excess of the available resources • Kubelet is responsible for the running state of each node (that is, ensuring that all containers on the node are healthy). It takes care of starting, stopping, and maintaining application containers (organized into pods) https://mesosphere.com/blog/kubernetes-and-the-dcos/
- 7. Building blocks pods • A Pod is the basic building block of Kubernetes–the smallest and simplest unit in the Kubernetes object model that you create or deploy. • A Pod represents a running process on your cluster. • A Pod encapsulates an application container (or, in some cases, multiple containers) • Each Pod is assigned a unique IP addres • Containers inside a Pod can communicate with one another using localhost • Pods are functionally identical and therefore ephemeral and replaceable - no saved state image from Bryan Dorsey GOTO talk
- 8. Building blocks service and labels • Kubernetes Pods are mortal. They are born and when they die, they are not resurrected. • A Kubernetes Service is an abstraction which defines a logical set of Pods and a policy by which to access them. • Service has static ip address • Load balances incoming requests across grouped pods • Services find their group of Pods using Labels • A Label is a key/value pair attached to everything and convey user-defined attributes • Metadata with semantic meaning and Grouping Mechanism • Query on labels to do things like dashboards image from Bryan Dorsey GOTO talk
- 9. Building blocks replication controller • Replication Controllers ensure the specified number of Pod “replicas” are running at any one given time. • Controll loop • If one Pod dies then the Replication Controller will replace it to maintain a total count of specified pods • Have one job: ensure N copies of a pod • if too few, start new ones • if too many, kill some • group == selector image from Bryan Dorsey GOTO talk
- 10. Building blocks volumes • If Pods are ephemeral how can I persist my container data across container restarts? • Well, Kubernetes supports the concept of Volumes so you can use a Volume type that is persistent. • Look like Directories to Containers • Volume options • mounted local storage device such as a disk • network file systems (and similar services) • Cloud Provider Block Storage (Google, AWS, Azure) image from Bryan Dorsey GOTO talk
- 11. Example apiVersion: apps/v1beta1 kind: Deployment metadata: name: nginx-deployment spec: replicas: 2 # tells deployment to run 2 pods matching the template template: # create pods using pod definition in this template metadata: # name is not included in the meta data as a unique name is # generated from the deployment name labels: app: nginx spec: containers: - name: nginx image: nginx:1.7.9 ports: - containerPort: 80 apiVersion: v1 kind: Service metadata: name: nginx-service spec: ports: - port: 8000 # the port that this service should serve on targetPort: 80 protocol: TCP # just like the selector in the deployment, # but this time it identifies the set of pods to load balance # traffic to. selector: app: nginx • To start working we describe our jobs in YAML or JSON • Submit to master, he will schedule job for us somewhere in the cluster • Pods and replication controllers could be merged into Deployments kubectl create -f ./deployment.yaml kubectl create -f ./service.yaml
- 12. Patterns • Canary update • Only a part of the audience get access to the new version of the app, while the rest still access the “old” version one. • very useful when we want to be sure about stability in case of any changes which may be breaking, and have big side effects. • Rolling updates • Rolling updates allow Deployments update to take place with zero downtime by incrementally updating Pods instances with new ones. • New Pods will be scheduled on Nodes with available resources.
- 13. Where to go next • kubernetes.io • Google Kubernetes Engine • Play with kubernetes • hello Minikube, test on your machine • Read Borg and Omega papers :) https://github.com/kubernetes/minikube
- 14. Questions? Thank you for your attention :) milossimicsimo@gmail.com@MilosSimicSimoMilosSimic http://www.businesscloudnews.com/2016/06/02/emc-launches-storage-provisioning- framework-for-containers/