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![Replication
Controller Pod
Pod
frontend
Pod
frontend
Pod Pod
app = demo app = demo app = demo
ReplicaSet
#pods = 3
app = demo
color in (blue,grey)
show: version = v2
Similar to ReplicationController but supports generalized Selectors
ReplicaSets (1.2)
selector:
matchLabels:
app: demo
matchExpressions:
- {key: color, operator: In, values: [blue,grey]}
color = blue color = blue color = grey](https://image.slidesharecdn.com/k8sfrankfurt-160715082149/85/Kubernetes-Frankfurt-21-320.jpg)
Uploaded byloodse
Kubernetes Frankfurt
The document provides an overview of Docker and Kubernetes. It explains that Docker is a tool that allows applications to be run in isolated containers, while Kubernetes is an open-source system for automating deployment, scaling, and management of containerized applications. The document outlines basic Kubernetes concepts like pods, replication controllers, services, deployments and rollouts that allow scheduling and maintaining application containers across a cluster.
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Kubernetes Frankfurt
- 2. What is thisDocker thing? • A company? • A format? • An API?
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- 5. Kubernetes Greek for “Helmsman”; also the root of the words “governor” and “cybernetic” • Runs and manages containers •Inspired and informed by Google’s experiences and internal systems • Supports multiple cloud and bare-metal environments • Supports multiple container runtimes • 100% Open source, written in Go Manage applications, not machines
- 6. Everything at Google runs in containers: • Gmail, Web Search, Maps, ... •MapReduce, batch, ... • GFS, Colossus, ... • Even Google’s Cloud Platform: VMs run in containers! Google launch over 2 billion containers per week
- 7. Start with aCluster • Laptop to high-availability multi-node cluster • Hosted or self managed • On-Premise or Cloud • Bare Metal or Virtual Machines • Most OSes (inc. RedHat Atomic, Fedora, CentOS) • Or just a bunch of Raspberry Pis • Many options, See Matrix for details Kubernetes Cluster Matrix: http://bit.ly/1MmhpMW
- 8. etcd scheduler controller-manager apiserver kubelet docker kube-proxyiptables 1. User sends Pod request to API server 2. API server saves pod info to etcd (unscheduled) 3. Scheduler finds unscheduled pod and schedules it to node. 4. Kubelet sees pod scheduled to it and tells docker to run the container. 5. Docker runs the container. 1 2 5 3 4
- 9. Kubelet Kubelet Kubelet KubernetesMaster Scheduler API Server Start with a Cluster
- 10.
- 11. Pods Pod Git Synchronizer Node.js App Container Volume Consumersgit Repo Can be used to group multiple containers & shared volumes Containers within a pod are tightly coupled Shared namespaces •Containers in a pod share IP, port and IPC namespaces • Containers in a pod talk to each other through localhost
- 12. Pod Networking (acrossnodes) Pods have IPs which are routable Pods can reach each other without NAT Even across nodes No Brokering of Port Numbers These are fundamental requirements Many solutions Flannel, Weave, OpenVSwitch, Cloud Provider 10.1.2.0/24 10.1.1.0/24 10.1.1.211 10.1.1.2 10.1.2.106 10.1.3.0/24 10.1.3.4510.1.3.17 10.1.3.0/24
- 13. Client Pod Container Pod Container Pod ContainerContainer A logical grouping of pods that perform the same function • grouped by label selector Load balances incoming requests across constituent pods Choice of pod is random but supports session affinity (ClientIP) Gets a stable virtual IP and port •also a DNS nametype = FE Services Service Label selector: type = FE VIP type = FE type = FE type = FE
- 14. Pod Pod frontend Pod frontend Pod Pod type = FE version = v2 type = FE version = v2 ●Metadata with semantic meaning ● Membership identifier ● The only Grouping Mechanism Behavior Benefits ➔ Allow for intent of many users (e.g. dashboards) ➔ Build higher level systems … ➔ Queryable by Selectors Labels Dashboard selector: type = FE Dashboard selector: version = v2
- 15. Replication Controller Pod Pod frontend Pod frontend Pod Pod Replication Controller #pods = 1 version = v2 show: version = v2 version= v1 version = v1version = v2 Replication Controller #pods = 2 version = v1 show: version = v2 Behavior Benefits ● Keeps Pods running ● Gives direct control of Pods ● Grouped by Label Selector ➔ Recreates Pods, maintains desired state ➔ Fine-grained control for scaling ➔ Standard grouping semantics Replication Controllers
- 16. Replication Controllers Replication Controller Replication Controller - Name = “backend” -Selector = {“name”: “backend”} - Template = { ... } - NumReplicas = 4 API Server 3 Start 1 more OK 4 How many? How many? Canonical example of control loops Have one job: ensure N copies of a pod • if too few, start new ones • if too many, kill some • group == selector Replicated pods are fungible • No implied order or identity
- 17. Pod Pod frontend Pod frontend Pod Pod type = FE version = v2 type = FE version = v2 ●Metadata with semantic meaning ● Membership identifier ● The only Grouping Mechanism Behavior Benefits ➔ Allow for intent of many users (e.g. dashboards) ➔ Build higher level systems … ➔ Queryable by Selectors Labels Dashboard selector: type = FE Dashboard selector: version = v2
- 18. Deployment RS RS Pod Pod Pod env:test env: test env: test Pod env: test version: v2 version: v2 version: v2 version: v2
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- 20. Pod Pod frontend Pod frontend Pod Pod env = qa env = test ●env = prod ● tier != backend ● env = prod, tier !=backend Expressions ● env in (test,qa) ● release notin (stable,beta) ● tier ● !tier Generalized Labels (1.2) env = prod Pod env = prod Dashboard selector: env = notin(prod)
- 21. Replication Controller Pod Pod frontend Pod frontend Pod Pod app = demoapp = demo app = demo ReplicaSet #pods = 3 app = demo color in (blue,grey) show: version = v2 Similar to ReplicationController but supports generalized Selectors ReplicaSets (1.2) selector: matchLabels: app: demo matchExpressions: - {key: color, operator: In, values: [blue,grey]} color = blue color = blue color = grey
- 22. Rolling Update kubectl rolling-update API kubectl rolling-update Create frontend-rc-v2 kubectl rolling-update Create frontend-rc-v2 Scale frontend-rc-v2 up to 1 kubectl rolling-update Create frontend-rc-v2 Scale frontend-rc-v2 up to 1 Scale frontend-rc-v1 down to 1 kubectl rolling-update Create frontend-rc-v2 Scale frontend-rc-v2 up to 1 Scale frontend-rc-v1 down to 1 Scale frontend-rc-v2 up to 2 kubectl rolling-update Create frontend-rc-v2 Scale frontend-rc-v2 up to 1 Scale frontend-rc-v1 down to 1 Scale frontend-rc-v2 up to 2 Scale frontend-rc-v1 down to 0 kubectl rolling-update Scale frontend-rc-v2 up to 1 Scale frontend-rc-v1 down to 1 Scale frontend-rc-v2 up to 2 Scale frontend-rc-v1 down to 0 Delete frontend-rc-v1 PodPod frontend Pod version = v1version = v2version= v1 RC version = v1 type = BE #pods = 2 show: version = v2 type = BE type = BE RC version = v2 type = BE #pods = 0 show: version = v2 Pod version = v2 type = BE kubectl rolling-update is imperative, client-side RC version = v1 type = BE #pods = 2 show: version = v2 RC version = v1 type = BE #pods = 1 show: version = v2 RC version = v1 type = BE #pods = 0 show: version = v2 RC version = v2 type = BE #pods = 1 show: version = v2 RC version = v2 type = BE #pods = 2 show: version = v2 be-svc
- 23. Rollout API DeploymentDeployment Create frontend-1234567 Deployment Create frontend-1234567 Scale frontend-1234567 up to 1 Deployment Create frontend-1234567 Scale frontend-1234567 up to 1 Scale frontend-7654321 down to 0 Pod Pod frontend Pod version = v1 ReplicaSet frontend-1234567 version = v2 type =BE #pods = 0 show: version = v2 ReplicaSet frontend-7654321 version = v1 type = BE #pods = 2 version: v2 ReplicaSet frontend-7654321 version: v1 type: BE #pods = 0 version: v1 ReplicaSet frontend-1234567 version = v2 type = BE #pods = 1 show: version = v2 ReplicaSet frontend-1234567 version: v2 type: BE #pods = 2 type = BE type = BE Pod version: v2 type = BE Servic e be-svc Deployment Create frontend-1234567 Scale frontend-1234567 up to 1 Scale frontend-7654321 down to 0 Scale frontend-1234567 up to 2 kubectl edit deployment ...
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