Kubernetes is an open-source system for managing containerized applications across multiple hosts. It provides basic mechanisms for deployment, maintenance, and scaling of applications. Kubernetes clusters have a master node that manages the cluster and worker nodes that host the application containers. The master node schedules containers on workers and ensures desired states are maintained. Kubernetes provides primitive resources like pods, services, replication controllers and others to deploy and scale applications on the cluster.

1. Kubernetes
dj.kim

2. dj.kim
Flitto Server Engineer

3. Docker
make it easier to create, deploy and run applications
by using containers

4. Kubernetes
manage a cluster of linux container as a single system to
accelerate Dev and simplify Ops

5. Architecture

6. Master node

7. Master node
master
kubectl api server
scheduler
etcd
controller manager

8. Master node
master
api server
node
kubletkubectl

9. Master node
master
node
api server
scheduler
node
node
node
kublet
pod pod pod
pod pod
kublet
kublet
kublet
cpuL 60%
memory 72%
cpuL 40%
memory 50%
cpuL 20%
memory 25%
cpuL 0%
memory 0%
pod
kubectl

10. Master node
master
api server
scheduler
etcd
kubectl

11. Master node
master
api server
scheduler
etcd
controller manager
contoller
Node controller
Replication controller
Endpoint controller
Service Account & Token
Controllers
kubectl

12. Master node
master
api server
scheduler
etcd
controller manager
cloud controller manager
kubectl

13. Node

14. Node
worker node
masterapi server
kublet kube proxy container runtime cAdvisor

15. Node
worker node
master api server
kublet kube proxy container runtime cAdvisor

16. Node
worker node
master api server
kublet kube proxy container runtime
pod pod pod
internet
cAdvisor

17. Node
worker node
master api server
kublet kube proxy container runtime
pod pod pod
internet
container
cAdvisor

18. Kubernetes
Concept

19. Kubernetes resource
● kubectl
● kubectl + yaml
● api server
● language extension

20. Pod
A Pod encapsulates an application container(s),
storage resources, a unique network IP, and options
that how the container(s) should run

21. pod :: share ip, port and volume
pod
container
meta
● name
● labels
volume
volume
container
volume

22. pod :: share ip, port and volume
pod
container
meta
● name
● labels
volume
volume
container
volume
Design pattern
● side car pattern
● ambassador pattern
● adapter pattern

23. Service
load balance of pods

24. Service
Service
● label = app:node-app
Pod
● label = app:node-app
Pod
● label = app:node-app
Pod
● label = app:node-app
internet
kube proxy

25. Service_NodePort
Service
● label = app:node-app
Pod
● label = app:node-app
Pod
● label = app:node-app
Pod
● label = app:node-app

26. Service
Service
● label = app:node-app
Pod
● label = app:node-app
Pod
● label = app:node-app
Pod
● label = app:node-app
externalIp

27. Service_externalName
pod
container
service external service
ex) RDS,...
dns:
rds.domain.com

28. Namespace
logical unit in cluster

29. Namespace : system quota, user access policy
cluster
namespace: dev namespace: qa namespace: prod
pod pod
service
pod pod
service
pod pod
service
cpu: 1000ms
memory: 10G
cpu: 1000ms
memory: 10G
cpu: 2000ms
memory: 20G

30. Namespace : physical isolation
cluster
pod
container
● namespace: dev
container
● namespace: pod
pod
container
● namespace: dev
container
● namespace: pod

31. Controller
manage pods

32. ReplicaSet & ReplicationController
ReplicaSet
selector: label=app.node-app || label in (app.node-app, ..)
template: image: hello-node, port=3000
replicas: 3
pod
label=app.node-app
container
image: hello-node
pod
label=app.node-app
container
image: hello-node
pod
label=app.node-app
container
image: hello-node

33. Blue/Green deployment

34. Blue/Green deployment

35. Rolling upgrade

36. Rolling upgrade

37. Rolling upgrade

38. Deployment
Deployment
selector: label=app.node-app
template: image: hello-node, port=3000
replicas: 3
strategy:
type: RollingUpdate
pod
label=app.node-app
container
image: hello-node
pod
label=app.node-app
container
image: hello-node
pod
label=app.node-app
container
image: hello-node

39. Probe
health check

40. Probe_liveness probe

41. Probe_readiness probe

42. Deployment
Deployment
selector: label=app.node-app
template: image: hello-node, port=3000
replicas: 3
strategy:
type: RollingUpdate
pod
label=app.node-app
container
image: hello-node
readinessProbe:
httpGet:
path: /healthCheck
port: 3000
pod
label=app.node-app
container
image: hello-node
readinessProbe:
httpGet:
path: /healthCheck
port: 3000
pod
label=app.node-app
container
image: hello-node
readinessProbe:
httpGet:
path: /healthCheck
port: 3000

43. Controller
DaemonSet, Job, StatefulSet

44. Volume
disk

45. Volume_emptyDir
pod
container
● /config
volume
container
● /app/config

46. Volume_hostPath
Node
pod
container
● /app/logs
container
● /app/logs
pod
container
● /app/logs
container
● /app/logs
volume
● /logs

47. Volume_elasticBlockStore
aws ec2 instance
pod
container
● /app/logs
container
● /app/logs
pod
container
● /app/logs
container
● /app/logs
ebs
● /logs

48. Volume_persistentVolume

49. Volume_persistentVolume
aws ec2 instance
pod
container
● /app/logs
container
● /app/logs
pod
container
● /app/logs
container
● /app/logs
ebs
● /logs
persistentVolumeClaim
persistentVolume

50. Volume_persistentVolume
aws ec2 instance
pod
container
● /app/logs
container
● /app/logs
pod
container
● /app/logs
container
● /app/logs
ebs
● /logs

51. ConfigMap & Security
configuration

52. ConfigMap & Security

53. ConfigMap & Security
● pass by ENV veriable
● pass by ENV file

54. ConfigMap & Security
● pass by ENV veriable
● pass by ENV file
secretKeyRef

55. Service Ingress
L7 LoadBalancer

56. Service_ingress

57. Service_ingress
Service (NodePort)
● label = app:node-app
Pod
● label =
app:nod
e-app
Pod
● label =
app:nod
e-app
Pod
● label =
app:nod
e-app
kube proxy
Nginx ingress controller
ingress
Service (NodePort)
● label = app:node-app
Pod
● label =
app:nod
e-app
Pod
● label =
app:nod
e-app
Pod
● label =
app:nod
e-app
/users /products
kube proxy

58. Service_ingress
Service (NodePort)
● label = app:node-app
Pod
● label =
app:nod
e-app
Pod
● label =
app:nod
e-app
Pod
● label =
app:nod
e-app
kube
proxy
kube
proxy
kube
proxy
Nginx ingress controller
ingress
Service (NodePort)
● label = app:node-app
Pod
● label =
app:nod
e-app
Pod
● label =
app:nod
e-app
Pod
● label =
app:nod
e-app
kube
proxy
kube
proxy
kube
proxy
/users /products

59. Resource Management
CPU, Memory

60. Require, Limit
request
limit

61. Overcommitted_cpu
node cpu availability
limitnode cpu availability
Overcommitted
node cpu availability
node cpu availability

62. Overcommitted_memory
node cpu availability
limitnode cpu availability
Overcommitted
restart

63. Scheduling
advenced

64. Taints & tolerations
Master
Node
Taints:
app=node-app:NoSchedule
Node Node
container
scheduler

65. Taints & tolerations
Master
Node
Taints:
app=node-app:NoSchedule
Node Node
container
scheduler
container

66. Taints & tolerations
Master
Node
Taints:
app=node-app:NoSchedule
Node Node
container
scheduler
container
container
tolerations:
app=node-app

67. Taints & tolerations
Master
Node
Taints:
app=node-app:NoSchedule
Node Node
container
scheduler
container
container
tolerations:
app=node-app
● NoSchedule
● PreferNoSchedule
● NoExecute

68. Affinity

69. 아직 끝나지 않았습니다..

70. k8s Monitoring
k8s Security
k8s Network policy
k8s Autoscaling