This presentation includes information on Kubernetes Architecture, Container Orchestration, Internal Routing, External Routing, Configuration Management, Credentials Management, Persistent Volumes, Rolling Out Updates, Autoscaling, Package Management, and a Hello World example using Helm.

1. Deep Dive into Kubernetes
Part 1
Imesh Gunaratne, WSO2

2. Agenda
● Kubernetes Architecture
● Container Orchestration:
○ Pods
○ Replica Sets
○ Deployments
● Internal Routing
○ Services
● External Routing
○ Ingresses & Ingress Controllers

3. Agenda Cont.
● Configuration Management
○ Config Maps
● Credentials Management
○ Secrets
● Persistent Volumes
● Rolling Out Updates
● Autoscaling
○ Horizontal Pod Autoscalers

4. Agenda Cont.
● Package Management
○ Helm
● Hello World Example

5. Kubernetes Architecture

6. Kubernetes Architecture
Node 1 Node 2 Node nMaster
API
Overlay Network
UI
CLI
Container Registry
API Server
Scheduler
Controller
etcd

7. Container Orchestration

8. Pods
● A pod is a group of containers that
share the file system, users, network
interfaces, etc
● By default a pod will include two
containers: one for the given docker
image and other for the network
interface
C1 C2 Cn
apiVersion: v1
kind: Pod
metadata:
name: myapp-pod
labels:
app: myapp
spec:
containers:
- name: myapp-container
image: busybox
command: ['sh', '-c', 'echo
Hello Kubernetes! && sleep 3600']

9. Replica Sets
● Replica Sets are used for
orchestrating pods
● They define the docker images,
resources, env. variables, ports,
etc required for creating pods
apiVersion: apps/v1
kind: ReplicaSet
metadata:
name: frontend
labels:
app: guestbook
spec:
replicas: 3
selector:
matchLabels:
tier: frontend
matchExpressions:
- {key: tier, operator: In}
template:
metadata:
labels:
...
spec:
containers:
- name: php-redis
image: foo:bar
ports:
- containerPort: 80
Replica Set
C1 C2

10. Deployments
● A deployment is used for
orchestrating pods via replica sets:
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.7.9
ports:
- containerPort: 80
Replica Set
Deployment
C1 C2

11. Internal Routing

12. Services
kind: Service
apiVersion: v1
metadata:
name: my-service
spec:
selector:
app: MyApp
ports:
- protocol: TCP
port: 80
targetPort: 9376
Replica Set
Deployment
Service
● A service provides a layer 4 load
balancer for pods:
C1 C2

13. Pod to Pod Communication
Replica Set A
Deployment A
ServiceA
C1 C2
Deployment B
Replica Set B
C3 C4
ServiceB

14. External Routing

15. Ingresses
Replica Set
Deployment
Service
Ingress
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: test-ingress
annotations:
nginx.ingress.kubernetes.io/rewri
te-target: /
spec:
rules:
- http:
paths:
- path: /testpath
backend:
serviceName: test
servicePort: 80
● An ingress is used for configuring a
load balancer for external routing
C1 C2

16. Ingresses
Replica Set
Deployment
Service
Ingress
Ingress
Controller
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: test-ingress
annotations:
nginx.ingress.kubernetes.io/rewri
te-target: /
spec:
rules:
- http:
paths:
- path: /testpath
backend:
serviceName: test
servicePort: 80
● An ingress is used for configuring a
load balancer for external routing
C1 C2

17. Ingresses
Replica Set
Deployment
Service
Ingress
Ingress
Controller
LoadBalancer
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: test-ingress
annotations:
nginx.ingress.kubernetes.io/rewri
te-target: /
spec:
rules:
- http:
paths:
- path: /testpath
backend:
serviceName: test
servicePort: 80
● An ingress is used for configuring a
load balancer for external routing
C1 C2

18. Configuration Management

19. ConfigMaps
Replica Set
Deployment
Service
Ingress
Ingress
Controller
LoadBalancer
Config MapsConfig Files
● Configuration files can be injected
into pods using ConfigMaps
● A ConfigMap can be created for
key/value pairs, files and folders
Config MapsConfig Maps
C1 C2

20. Credentials Management

21. Config Maps
Secrets
Replica Set
Deployment
Service
Ingress
Ingress
Controller
LoadBalancer
Config Files
● Sensitive data such as
credentials, encryption keys can
be securely injected using
secrets
Config MapsConfig MapsConfig MapsSecrets
Config Maps
Credentials
C1 C2

22. Persistent Volumes

23. Config Maps
Persistent Volumes
Replica Set
Deployment
Config Files
Config Maps
Credentials
C1 C2
Persistent Volume ClaimPersistent Volumes
Service
● PVC defines volume size, and
type: ReadOnly, ReadWrite,
ReadWriteMany

24. Persistent Volume Types
● GCEPersistentDisk
● AWSElasticBlockStore
● AzureFile
● AzureDisk
● FC (Fibre Channel)**
● FlexVolume
● Flocker
● NFS
● iSCSI
● RBD (Ceph Block Device)
● CephFS
● Cinder (OpenStack block storage)
● Glusterfs
● VsphereVolume
● Quobyte Volumes
● VMware Photon
● Portworx Volumes
● ScaleIO Volumes
● StorageOS
https://kubernetes.io/docs/concepts/storage/persistent-volumes/#types-of-persistent-volumes

25. Rolling Out Updates

26. Deployment Process
Deployment V1 V1 Deploying...

27. Replica Set V1
Deployment V1 V1 Deploying...
Deployment Process

28. Replica Set V1
Deployment V1
P1 - V1 P2 - V1 Service
C1 C2
V1 Pods Starting...
Deployment Process

29. C1
Replica Set V1
Deployment V1
P1 - V1 P2 - V1 Service
C2
V1 Pods Activating...
Deployment Process

30. C1
Replica Set V1
Deployment V1
C2
P1 - V1 P2 - V1 Service
V1 Pods Healthy
Deployment Process

31. C1
Replica Set V1
Deployment V1
C2
P1 - V1 P2 - V1
Deployment V2
Service
Deploying V2...
Rolling Update Process

32. C1
Replica Set V1
Deployment V1
C2
P1 - V1 P2 - V1
Deployment V2
Replica Set V2
Service
Deploying V2...
Rolling Update Process

33. Replica Set V1
Deployment V1
C2
P1 - V1 P2 - V1
Deployment V2
Replica Set V2
P1 - V2Service
C3
V2 Pods Starting...
C4
P2 - V2
C1
Rolling Update Process

34. C1
Replica Set V1
Deployment V1
C2
P1 - V1 P2 - V1
Deployment V2
Replica Set V2
C3
P1 - V2Service
V2 Pods Activating...
P2 - V2
C4
Rolling Update Process

35. Replica Set V1
Deployment V1
P1 - V1 P2 - V1
Deployment V2
Replica Set V2
C3 C4
P1 - V2 P2 - V2
C1 C2
Service
V2 Pods Healthy
Rolling Update Process

36. Autoscaling

37. Horizontal Pod Autoscalers
Replica Set
Deployment
Service
● Enable autoscaling for pods based on CPU utilization
Horizontal Pod
Autoscaler
Resource Metrics API
C1 C2

38. Package Management

39. Helm
● Helm is the Kubernetes package manager.
● It uses Charts for defining, installing and upgrading
applications on Kubernetes.
● Runtime configurations can be templated and
parameterized.
● Existing Charts can be reused and added as dependencies to
new Charts.
● Helm is managed by CNCF.
https://docs.helm.sh

40. Helm Hello World
# templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
Name: hello-world
spec:
replicas: 1
template:
metadata:
labels:
app: hello-world
spec:
containers:
- name: hello-world
image:
gcr.io/google-samples/node-hello
:1.0
ports:
- containerPort: 8080
protocol: TCP
# chart.yaml
name: apps/v1
version:
# templates/service.yaml
kind: Service
apiVersion: v1
metadata:
name: hello-world
spec:
type: NodePort
selector:
app: hello-world
ports:
- protocol: TCP
port: 8080
targetPort: 8080

41. Hello World Demo

42. Questions & Feedback

43. References

44. References
● Kubernetes Documentation:
○ https://kubernetes.io/docs/
● An Introduction to Kubernetes:
○ https://www.slideshare.net/imesh/an-introduction-to-kubernetes
● WSO2Con US 2015 Kubernetes: a platform for automating deployment,
scaling, and operations:
○ https://www.slideshare.net/BrianGrant11/wso2con-us-2015-kube
rnetes-a-platform-for-automating-deployment-scaling-and-operati
ons
● Kubernetes: An Overview:
○ https://thenewstack.io/kubernetes-an-overview/

45. References Cont.
● Helm Documentation:
○ https://docs.helm.sh
● The missing CI/CD Kubernetes component: Helm package manager
○ https://medium.com/@gajus/the-missing-ci-cd-kubernetes-compon
ent-helm-package-manager-1fe002aac680

46. Thank You!