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Kubernetes Overview 101.pptxKubernetes Overview 101.pptx
- 1. Kubernetes 101 Technical ProductManagement CNABU
- 2. 2 Agenda Why Kubernetes?? Introduction toKubernetes Kubernetes Components Kubernetes Basic Concepts Conclusion & Questions
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- 4. 4 Linux Kernel 4.2 Linux“Container” Host Linux Kernel 4.2 Management & User-space Tools (Libraries, Additional Software, & Docs) Configuration | Application SW App Process 1 App Process 2 App Process n Container 1 Standard Linux Host Docker Engine Photon OS Tools, Libs, SW Container image built w/Dockerfile Container n Tools, Libs, SW #docker run containerimage Why Use Containers?
- 5. 5 Challenges with Containers CONTAINERSIN DEVELOPMENT CONTAINERS IN PRODUCTION THE “LEARNING CLIFF” Load Balancing Security High Availability Application Updates Scaling up/down Repeatable Deployments Replication Scheduling Containers Containers
- 6. 6 Movement from Monolithicto Microservice Architecture Developer pushes to git repository GitHub Webhook Triggers Jenkins Jenkins copies GitHub Repo • Dockerfile • App code • Test code Jenkins has Docker build an image based on the Dockerfile Jenkins Deploys the container with the application code and desired tests are executed
- 7. 7 Containers vs. ContainerSchedulers Physical Infrastructure Virtual Infrastructure IaaS Platform Services Application Developers Container Schedulers Containers
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- 9. 9 What is Kubernetes(K8s) • Kubernetes, is an open-source platform for managing, automating deployment, scaling, and operating containerized applications across a cluster of worker nodes. Capabilities: • Deploy your applications quickly and predictably • Scale your applications on the fly • Seamlessly roll out new features • Optimize use of your hardware by using only the resources you need Role: • K8s sits in the Container as a Service (CaaS) or Container orchestration layer
- 10. 10 K8s introduces alot new concepts • 10,000 ft. View K8s Cluster 1 Worker node 1 Worker node 2 Worker node 3 Master vCenter Pod 1 Pod 2 Pod 3 Pod 4 Pod 5 Pod 6 ESXi 1 ESXi 2 ESXi 3 VM 1 VM 2 VM 3 VM 4 VM 5 VM 6 • Cluster • Master • Workers (nodes) • Pods • Cluster • vCenter • ESXi (Hosts) • VMs
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- 12. 12 K8s Cluster • Consistsof a master and a group of worker nodes • Namespaces – Mechanism to partition resources into logically named groups K8s Cluster 1 Worker node 1 Worker node 2 Worker node 3 Master
- 13. 13 K8s Master • APIServer • Scheduler • Dashboard (UI) • Controller Manager – Replication Controller K8s Cluster 1 Worker node 1 Worker node 3 Master Worker node 2 Master Dashboard (UI) API Server Scheduler Controller Manager
- 14. 14 K8s Worker Node •Kubelet – Is an agent on the Nodes is watching for ‘PodSpecs’ to determine what it is supposed to run • Kube-Proxy – Is a daemon watching the K8s ‘services’ on the API Server and implements east/west load-balancing on the nodes using NAT in IPTables • Container Runtime – Docker – Rkt K8s Cluster 1 Worker node 1 Worker node 2 Worker node 3 Master Worker node 1 Kubelet Kube-Proxy Container Runtime
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- 16. 17 Pods • A pod(as in a pod of whales or pea pod) is a group of one or more containers • Containers within a pod share an IP address and port space, and can find each other via localhost • Containers in a Pod also share the same data volumes • Pods are considered to be ephemeral Pod 1 Container 1 Tools, Libs, SW Container 2 Tools, Libs, SW Pod 2 Container 1 Tools, Libs, SW Container 2 Tools, Libs, SW
- 17. 18 Labels • A Labelis a key/value pair attached to Pods and convey user-defined attributes. • You can then use label selectors to select Pods with particular Labels and apply Services or Replication Controllers to them. • Labels can be attached to objects at creation time and subsequently added and modified at any time Pod 1 Container 1 Tools, Libs, SW Container 2 Tools, Libs, SW Pod 2 Container 1 Tools, Libs, SW Container 2 Tools, Libs, SW Labels: tier=frontend, app=myapp Labels: tier=backend, app=myapp
- 18. 19 Persistent Volume Claim Poolof Persistent Volumes VSAN VMFS NFS Cloud Admin Developer • Provisioning • Registers PVs in a Pool • Reclamation • Request Volume Claim • Releasing Volume Claim Developer Owned Kubernetes Cluster Administrator Owned Worker Claim Pod
- 19. 20 Services • Services Types –ClusterIP – NodePort – Loadbalancer • Service Discovery – DNS – Environmental variables Worker Node Service Pod 1 Pod 2 Pod N Node IP: 192.168.10.10 IP: 10.2.3.14 DNS: service1.cluster.local Port: 9443 NodePort: 31233 Protocol: TCP Port: 9443
- 20. 21 K8s Cluster 1 ReplicaSet.yaml ContainerImage1 Replicas:3 ContainerImage2 Replicas: 2 Replication Controller • Features for replicating Pods – Auto-healing – Manual Scaling – Rolling Updates – Multiple Release Tracks Worker (Container Host) P1R1 Worker (Container Host) P1R2 P2R1 P1R1 P2R1 Worker (Container Host) P1R3 P2R2 P2R2 Master API K K K Deployment_Y.yaml ContainerImage1 Replicas: 1 ContainerImage2 Replicas: 2 P1R1 P1R2 P2R1
- 21. 22 StatefulSet • The wayof launching ordered replica’s of Pods. • Enables running pods in “clustered mode” – Master/Slave applications • Valuable for applications that require: – Stable and unique network identifiers – Stable persistent storage – Ordered deployment and scaling • Headless service required • Examples – Zookeeper, Cassandra, etcd, MySQL, etc Pod 1 Pod 2 Pod 3 Pod 1 Pod 2 Pod 3 Creates Pods in sequence Deletes Pods in reverse sequence
- 22. 23 K8s Cluster 1 DaemonSet1.yaml DaemonSet •Runs a copy of a Pod on every node in the cluster • Newly created nodes automatically get the DaemonSet Pod(s) • When a node is removed a DaemonSet doesn’t get rescheduled Worker1 Pod1 Worker2 Pod2 Worker3 Pod3 Master API K K K
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Editor's Notes
- #3 Building a House Out of Lego
- #4 Application-centric management Raises the lvel of abstraction from running an OS Continuous development, integration, and deployment Loosely coupled, distributed, elastic, micro-services Cloud and OS portability Efficient resource utilization
- #5 No patching No Upgrades Immutable infrastructure
- #9 The first being everything in IT has an abbreviation or acronym k8s
- #10 The first being everything in IT has an abbreviation or acronym k8s
- #19 https://thenewstack.io/strategies-running-stateful-applications-kubernetes-persistent-volumes-claims/
- #20 If Pods are ephemeral and their IP address might change if they get restarted how can I reliability reference my backend container from a frontend container? Pods are ephemeral and will be removed/rescheduled continuously. Abstraction layer above sets of objects so that you don’t have to trace specific objects as they restart Provides single endpoint for the underlying set of objects (Pod Replicas) A logical, internal load balancer for a set of related pods (an application) A single IP address and DNS name to refer to the set of pods
- #22 https://thenewstack.io/deploy-highly-available-wordpress-instance-statefulset-kubernetes-1-5/
- #23 Logging Aggregators Monitoring Loadbalancers Generic Background job that needs to run on every node