This document provides a high-level overview of Kubernetes in under 30 minutes. It begins with basic concepts like nodes, pods, replica sets, deployments, and services. It then covers additional concepts like secrets, config maps, ingress, daemon sets, pet sets/stateful sets and services. The document aims to explain the main components of Kubernetes and how they work together at a high level to deploy and manage container-based applications.

1. Kubernetes in
30 minutes
Mar 10, 2017
Daisuke Maki @lestrrat

3. Netscape Navigator

4. Netscape Navigator

5. Kubernetes

6. κυβερνήτης

7. k8s

8. “Something to do with
containers…?

9. •You know about containers
•You know about orchestration
•You know about the painful art of
deploying stuff
Assumptions

10. Docker

11. “Random containers doing their own sh*t”

12. Compose

13. “Foreman on Acid”

14. Swarm

15. “Clustering and Discovery”
(hey, we’re getting somewhere!)

16. =

17. “Batteries Included”

18. K8s on GCP
GKE GCE Networking
…and others

19. Basic Concepts

20. Node

21. Hosts running
k8s daemons

22. Node
kubelet
Node
kubelet
Node
kubelet
Master
Scheduler
etc..
API

23. Pod

24. Basic unit of
deployment in k8s
基本

25. Group of Containers

26. Container configurations

27. Shared storage

28. Pod
container

29. Pod
container
container

30. Pod
container
container
container

31. Pod
container
container
container
nginx
app
redis/cache
e.g.

32. Scheduled together
(“co-scheduled”)

33. Guaranteed to be
on the same node
(“co-located”)

34. Node NodeNode

35. Node NodeNode
Depends on each node’s resource availability
and each pod’s resource requirements

36. Node Node
container
container
container

37. Node Node
container
container
container
This will NEVER happen

38. Miscellaneous
• Each pod has its own IP address
• Pods are expected to be stateless

39. Replica Set

40. Keeps track of
Pod replicas

41. Replica Set
replicas: 3
template:

42. Replica Set
replicas: 3
template:
A

43. Replica Set
replicas: 3
template:
A B

44. Replica Set
replicas: 3
template:
CA B

45. Replica Set
replicas: 3
template:
CA B

46. Replica Set
replicas: 3
template:
A B

47. Replica Set
replicas: 3
template:
A B D

48. Deployment

49. Manages Replica Set
state transitions

50. Deployment
replicas: 3
template:

51. Deployment
replicas: 3
template:
Replica Set A
replicas: 3
template:

52. Deployment
replicas: 3
template:
Replica Set A
replicas: 3
template:
Change some settings,
please!

53. Deployment
replicas: 3
template:
Replica Set A
replicas: 3
template:
2
Change some settings,
please!

54. Deployment
replicas: 3
template:
Replica Set A
replicas: 3
template:
Replica Set B
replicas: 2
template:
2
Change some settings,
please!

55. Deployment
replicas: 3
template:
Replica Set A
replicas: 3
template:
Replica Set B
replicas: 2
template:
2
Change some settings,
please!

56. Deployment
replicas: 3
template:
Replica Set B
replicas: 2
template:
2
Change some settings,
please!

57. Keeps track of
state change history

58. Deployment
replicas: 3
template:

59. Deployment
replicas: 3
template:
A
replicas: 3
template:

60. Deployment
replicas: 3
template:
A
replicas: 3
template:
Change some settings,
please!

61. Deployment
replicas: 3
template:
A
replicas: 3
template:
2
Change some settings,
please!

62. Deployment
replicas: 3
template:
A
replicas: 3
template:
B
replicas: 2
template:
2
Change some settings,
please!

63. Deployment
replicas: 3
template:
A
replicas: 3
template:
B
replicas: 2
template:
2
Change some settings,
please!

64. Deployment
replicas: 3
template:
B
replicas: 2
template:
2
Change some settings,
please!

65. Deployment
replicas: 3
template:
B
replicas: 2
template:
2
Oh wait, I actually
didn’t want to do that…

66. Deployment
replicas: 3
template:
B
replicas: 2
template:
2
Oh wait, I actually
didn’t want to do that…
3

67. Deployment
replicas: 3
template:
B
replicas: 2
template:
2
Oh wait, I actually
didn’t want to do that…
rollback
3

68. Deployment
replicas: 3
template:
B
replicas: 2
template:
2
Oh wait, I actually
didn’t want to do that…
rollback
A
replicas: 3
template:
3

69. Deployment
replicas: 3
template:
B
replicas: 2
template:
2
Oh wait, I actually
didn’t want to do that…
rollback
A
replicas: 3
template:
3

70. Deployment
replicas: 3
template:
2
Oh wait, I actually
didn’t want to do that…
A
replicas: 3
template:
3

71. Services

72. Logical set of Pods
(and ways to access them)

73. Pod 10.0.96.2
Pod 10.0.96.3
Pod 10.0.96.3
Raw Pod Access

74. Pod 10.0.96.2
Pod 10.0.96.3
Pod 10.0.96.3
Raw Pod Access

75. Pod 10.0.96.2
Pod 10.0.96.3
Pod 10.0.96.3
Raw Pod Access

76. Pod 10.0.96.2
Pod 10.0.96.3
Raw Pod Access

77. Pod 10.0.96.2
Pod 10.0.96.3
Raw Pod Access

78. Pod 10.0.96.3
role=web
Access Via Service
Pod 10.0.96.4
role=web
Service
match role=web
Pod 10.0.96.2
role=web
Pod 10.0.96.5
role=db

79. Pod 10.0.96.3
role=web
Access Via Service
Pod 10.0.96.4
role=web
Service
match role=web
Pod 10.0.96.2
role=web
Pod 10.0.96.5
role=db

80. Pod 10.0.96.3
role=web
Access Via Service
Pod 10.0.96.4
role=web
Service
match role=web
Pod 10.0.96.2
role=web
Pod 10.0.96.5
role=db

81. Pod 10.0.96.3
role=web
Access Via Service
Pod 10.0.96.4
role=web
Service
match role=web
Pod 10.0.96.2
role=web
Pod 10.0.96.5
role=db

82. Access Via Service
Pod 10.0.96.4
role=web
Service
match role=web
Pod 10.0.96.2
role=web
Pod 10.0.96.5
role=db

83. Access Via Service
Pod 10.0.96.4
role=web
Service
match role=web
Pod 10.0.96.2
role=web
Pod 10.0.96.5
role=db

84. Access Via Service
Pod 10.0.96.6
role=web
Pod 10.0.96.4
role=web
Service
match role=web
Pod 10.0.96.2
role=web
Pod 10.0.96.5
role=db

85. Access Via Service
Pod 10.0.96.6
role=web
Pod 10.0.96.4
role=web
Service
match role=web
Pod 10.0.96.2
role=web
Pod 10.0.96.5
role=db

86. Secrets

87. Store pieces of
data in k8s

88. e.g. Identity Information

89. (securely)

90. (…in the future)

91. Secret
key1 → base64 value
key3 → base64 value
key2 → base64 value

92. Pod
container
volumes
container:
volumeMounts:
- name: certificates
mountPath: /etc/ssl/certs
volumes:
- name: certificates
secret:
secretName: ca-certificates

93. Pod
container
volumes
env:
- name: foo-secret
valueFrom:
secretKeyRef:
name: foo
value: secret-value

94. ConfigMaps

95. Same as Secrets
(Unprotected)

96. Ingress

97. Services are for within the
cluster only
(external IPs allowed, but don’ use that to serve
external requests)

98. (New since 1.2)
Inbound connections to
internal cluster services

99. Please checkout my presentation
https://docs.google.com/presentation/d/
11ZN6qgiuZZfVyhBK2hjp1vhp_5N0DOGnAmhPreS3L5A/pub?
start=false&loop=false&delayms=3000

100. DaemonSets

101. Ensure nodes run a copy of a Pod
Node
prometheus-exporter prometheus-exporter prometheus-exporter
Node Node

102. PetSets

103. PetSets
StatefulSets

104. Use only when *really* needed

105. Keeps unique IDs in replicas
(x-0, x-1, x-2,…)

106. Questions?