The document outlines the fundamentals of Kubernetes, an open-source platform for managing and deploying application containers across clusters. Key components include pods, labels, replication controllers, and services, which help in organizing and managing applications effectively. It also highlights storage solutions like volumes and persistent volumes, essential for data retention in Kubernetes environments.

1. Kubernetes (k8s)
Dharmit Shah
(@dharm1t)

2. Who am I?
@

3. About Me
● Software Engineer @ Red Hat
● Develop tools for Developers like you!
● CI/CD
● Previous Life:
○ Tech Support Engineer
○ Linux Admin
○ Django developer

5. What is Kubernetes?
● Open-source platform
● Deploy application containers across clusters of hosts
● Container-centric infrastructure
● Features:
○ Quickly deploy applications
○ Scale the applications
○ Rolling updates
● Physical and Virtual machines
● Google, Red Hat, Intel, Puppet, CoreOS, etc.

6. Key Concepts
● Pods
● Labels
● Services
● Replication Controllers
● Deployments
● Volumes
● Persistent Volumes
● …

7. Pods
● Smallest deployable units that can be created and managed in k8s
● Group of containers scheduled on the same host
● Share resources like volumes, IP address
● Containers within a pod can find each other via localhost
● Can also communicate using standard IPC
● Containers in different pods have distinct IP addresses and can not
communicate by IPC.

8. DEM0!

9. Labels
● Key/Value pairs that are attached to objects, such as pods
● Used to organize and select subsets of objects
● Example labels:
○ "release" : "stable", "release" : "canary"
○ "environment" : "dev", "environment" : "qa", "environment" :
"production"

10. DEM0!

11. Replication Controllers (rc)
● Ensures a specified number of pod “replicas” are running
● If there are more pods, it’ll kill some
● If there are less pods, it’ll start more
● Manages all the pods with labels which match the “selector”
● Increase/Decrease number of replicas on the fly

12. DEM0!

13. Services
● Pod IP addresses cannot be relied upon!
● What if pods (backend) provide some service to other pods (frontend)
and backend pods suddenly die?
● Services define logical set of Pods
● Set of Pods targeted by a Service is determined by “selector” (same
concept as rc)

14. DEM0!

15. Deployments
● Provides declarative updates for Pods and Replica Sets (next gen RC)
● Used to bring up Pods and Replica Sets
● Canary deployments

16. Volumes
● Just another directory accessible to the Pod
● Ceases to exist when Pod ceases to exist
● Support for many volume types; Pod can use any number of them
simultaneously
● Mounted at the specified paths within the image

17. Volume Types
● emptyDir
● hostPath
● gcePersistentDisk
● awsElasticBackStore
● nfs
● iscsi
● glusterfs
● rbd (Ceph)

18. DEM0!

19. Persistent Volume
● A piece of networked storage in the cluster provisioned by an
administrator
● Lifecycle independent of any individual pod that uses the PV
● Types:
○ GCEPersistentDisk
○ RBD (Ceph)
○ Glusterfs
○ NFS
○ iSCSI
○ …

20. DEM0!

21. Join the community!
● Slack - kubernetes.slack.com
● GitHub - https://github.com/kubernetes/kubernetes/

22. Questions?