kubernetes 1.3 - highlights
TRANSCRIPT
Kubernetes 1.3What’s New
Matt BatesCo-founder @JetstackHQ
5000+COMMITS
350+ CONTRIBUTORS
Headlines of 1.3
- Cluster Federation- PetSet- Init Containers- Rktnetes 1.0- Scalability- Minikube
Init Containers (#23567)
– Alpha feature– Run container(s) before the long-running main
pod container(s) are launched– Executed in sequential order– Only if init containers succeed do the main
container(s) start– Use cases:
– download files / clone repos– write out config files– etc
init-1 init-2
main-container
Stateful services (1.2)
- ReplicaSets (nee controllers) ensure N replicas of a pod template exist
- Only attribute that differs between pods is the name- Therefore same volume(s)
- Pods have no stable network identity other than an assigned pod IP- e.g. no fixed and predictable hostname
- Best for ‘shared-nothing, zero-coordination systems’
Photo credit: http://delectabledeliciousness.blogspot.co.uk
PetSet (#18016)
– New Alpha resource (apps/v1alpha1)– Stable and unique identity associated
with that instance of the storage– Consistent network identity– Predictable number of instances to ensure
that systems can form a quorum– Ability to migrate from node to node with
stable network identity (DNS name)– Scale up/down in a controlled fashion
PetSet (#18016)
PetSet pet-0.pet.default...
PetSetController
(KCM)
PV-0 PVC-0
API Server
Watches
Creates claim from template
BindsMounts
Creates and waits until ready
Service
1:1 mapping
PetSet (#18016)
PetSet pet-0.pet.default...
PetSetController
(KCM)
PV-0 PVC-0
API Server
Servicepet-1.
pet.default... PV-1 PVC-1
pet-2.pet.default... PV-2 PVC-2
eu-west-1beu-west-1a eu-west-1c
Recap: Cross-AZ clusters
Cross-AZ clusters (Ubernetes ‘Lite’) baked into 1.2
worker worker worker
Control Plane$ kubectl describe node worker1
...failure-domain.beta.kubernetes.io/region=eu-west1
failure-domain.beta.kubernetes.io/zone=eu-west1-a...
Cluster Federation/Ubernetes (#19313)
eu-central-1eu-west-1
worker worker worker
Cluster A Control Plane
worker worker worker
Cluster B Control Plane
Cluster Federation/Ubernetes (#19313)
eu-central-1eu-west-1
worker worker worker
Cluster A Control Plane
worker worker worker
Cluster B Control Plane
Federation Control PlaneFederation Controller Manager Federation API Server
Cluster Federation/Ubernetes (#19313)
– Focused on Federated Services at this stage– Create a Service at the Federation API Server:
– Creates matching Kubernetes Services in every cluster– Monitors the health of service “shards”– Manages DNS records in a public DNS provider (ie Google Cloud
DNS or AWS Route 53)– Note: backend Pods are currently added directly against the cluster API
endpoints
Federation Control PlaneFederation Controller Manager Federation API Server
DNS Provider
(Route 53, Google DNS)
kube-dnskube-dns
myservice.mynamespace.myfederation
myservice.mynamespace.myfederation.svc.jetstack.net
myservice.jetstack.net
myservice.mynamespace.myfederation.svc.eu-west-1.jetstack.net
myservice.mynamespace.myfederation.svc.eu-central-1.jetstack.net
Federation Control PlaneFederation Controller Manager Federation API Server
DNS Provider
(Route 53, Google DNS)
kube-dnskube-dns
myservice.jetstack.net
eu-west-1.jetstack.net eu-central-1.jetstack.net
rktnetes 1.0
– Kubernetes was built to ultimately be container runtime-agnostic
– First stable release that integrates the CoreOS rkt runtime, that can be used in-place of Docker
– Why Rkt?– rkt implements the open App Container Spec– Compatibility with init systems such as systemd
(nspawn)– Ability to launch VMs in pods for greater isolation
guarantee (using LKVM stage1)
Scalability
– Supports 2000-node clusters with decreased end-to-end pod startup time
– Under the bonnet, uses Protocol Buffer-based serialization in the API instead of JSON
Minikube
– Minikube starts a single node kubernetes cluster locally for purposes of development and testing.
– Packages and configures a Linux VM, Docker and all Kubernetes components, optimized for local development.
– Supports:– DNS– NodePorts– ConfigMaps and Secrets– Dashboards
– Does not support cloud-provider functionality (LoadBalancers, PersistentVolumes, Ingress)
More Hidden Gems..
https://blog.jetstack.io/blog/kubernetes-1-3-hidden-gems
