Marc Sluiter - 15 Kubernetes Features in 15 Minutes

@slintes#Devoxx #Kubernetes

15 Kubernetes Features in 15 Minutes

Marc Sluiter Luminis Technologies


Who am I?

• Software Engineer @ Luminis Technologies

• Java, Go, Angular2

• Working on

• Amdatu

• INAETICS

• CloudRTI


Kubernetes

• Greek for "helmsman" or “pilot"

• schedules, runs and manages containers in a cluster of virtual or physical machines

• declarative approach:

• try permanently to reach the declared cluster state


Kubernetes

• started by Google in 2014

• based on over 10 years experience (“Borg”)

• first release in Juli 2015

• donated to Cloud Native Computing Foundation

• 100% Open Source

• Go


#1 Pods

• smallest deployable unit

• small group of tightly coupled containers

• shared network and data volumes

• routable IP address

• mortal!


#2 ReplicaSets

• run x copies (replicas) of a pod

• start or kill pods if necessary

• handle pod failures

• health checks


#3 Deployments

• contains declaration of your application

• which containers (image / tag)

• environment variables

• data volumes

• defines number of replicas

• creates ReplicaSets, which in turn create Pods


Deployments cont.

• rolling updates:


#4 Services

• pods are mortal!

• services provide a permanent virtual IP and DNS name

• proxy traffic to selected pods

• simple load balancing including session affinity


#5 Ingress

• expose services to the outside world

• map URLs to services

• SSL termination

• needs ingress provider


#6 Namespaces

• Namespaces group kubernetes resources (pods, replicasets, deployments, …)

• by default everything is in the “default” namespace

• create namespaces for your environments (e.g. test, staging, production) and / or tenants

• restrict access to specific namespaces for k8s users

• namespaces can have separated networks (depends on network provider)


#7 Clusters

• a cluster is a set of virtual or physical machines (nodes), running a k8s master and one or more k8s worker nodes

• cluster federation:

• run a federation master, which knows all your clusters

• run your apps distributed across clusters, e.g. across Amazon / Google / … regions


#8 Secrets and ConfigMaps

• separate your application code (= images) and configuration

• both Secrets and ConfigMaps are key-value-pairs

• use Secrets for binary values (e.g. certificates, keys)

• use ConfigMaps for string values

• both can be read by the container via environment variables or mapped into a data volume e.g. like property files


#9 Data Volumes

• map directories into containers

• multiple containers in one pod share the same volumes

• many volume types:

• empty directory, host directory, Google Persistent Disk, Amazon Blob Store, NFS, glusterfs, rdb, cephs, git repository, …

• can be preconfigured by cluster admins for easier usage by cluster users


#10 PetSets

• a Pet is a stateful pod

• a PetSet has a scalable number of Pets

• a Pet is bound to a dynamically created data volume

• that data volume will never be deleted automatically

• the Pet is bound to the same volume on a restart


#11 Jobs

• sometimes you need to run short living tasks

• a Job ensures that a container which executes such a task runs successfully exactly once (ore more times)

• retry on failure

• ScheduledJobs can be started at specific times (like cron)


#12 DaemonSets

• DaemonSets run pods on all (or a selected set of) nodes in the cluster

• useful for running containers for logging and monitoring


#13 Autoscaling

• Horizontal Pod Autoscaling

• scales ReplicaSets based on pod’s CPU usage or app-provided metrics

• Cluster Autoscaling

• scale the number of nodes in your cluster based on CPU and memory usage

• depends on cloud provider


#14 API

• every functionality is provided via a REST API

• easy integration in your existing workflows (continuous delivery)

• command line tool “kubectl” (uses the REST API internally)


#15 Community!

• constantly growing community

• active on Stackoverflow, Google Groups and Slack

• many contributors from many companies

• KubeCon conference


Questions?


Thank you!


Links...

http://kubernetes.io @kubernetesio

https://github.com/kubernetes

http://www.luminis.eu http://luminis-technologies.com

http://www.amdatu.org http://www.inaetics.org

http://www.cloud-rti.com


Kubernetes architecture

• Master

• API server

• Controller

• Scheduler

• Workers

• Kubelet

• Proxy

• State only in etcd!