What's new in Kubernetes 1.3, including Init Containers, Stateful Services, PetSet, Cluster Federation, rktnetes, and some more hidden gems.

1. Kubernetes 1.3
What’s New
Matt Bates
Co-founder @JetstackHQ

2. 5000+
COMMITS
350+
CONTRIBUTORS

4. Headlines of 1.3
- Cluster Federation
- PetSet
- Init Containers
- Rktnetes 1.0
- Scalability
- Minikube

5. 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

6. 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

7. 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

8. PetSet (#18016)
PetSet
pet-0.
pet.default...
PetSet
Controller
(KCM)
PV-0 PVC-0
API Server
Watches
Creates claim from template
BindsMounts
Creates
and waits
until
ready
Service
1:1 mapping

9. PetSet (#18016)
PetSet
pet-0.
pet.default...
PetSet
Controller
(KCM)
PV-0 PVC-0
API Server
Service
pet-1.
pet.default... PV-1 PVC-1
pet-2.
pet.default... PV-2 PVC-2

10. 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.ku
bernetes.io/
zone=eu-west1-a
...

11. Cluster Federation/Ubernetes (#19313)
eu-central-1eu-west-1
worker worker worker
Cluster A Control Plane
worker worker worker
Cluster B Control Plane

12. 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

13. 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

14. 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

15. 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

16. 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)

17. 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

18. 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)

19. More Hidden Gems..
https://blog.jetstack.io/blog/kubernetes-1-3-hidden-gems

20. Matt Bates
bates@jetstack.io | @mattbates25
www.jetstack.io
hello@jetstack.io
@JetstackHQ
meetup.com/contain