a subjective introduction to Kubernetes basic concepts

1. Kubernetes
FROM ZERO TO HERO Seasoned Beginner

2. Agenda
1. Background
2. Why k8s?
3. K8s Basics
4. Helm charts

3. Personal Background
18 years of Java development
(Banks, Telcos, Government sector, E-
commerce lately)
Working on Linux since 1997
Advocating since 2015
3

4. Kubernetes
(aka k8s)
◂ Container-orchestration system for
← automating deployment
← scaling
← operations
of application containers across clusters of hosts
◂ Designed by Google, started in 2014
(previously Borg)
now maintained by Cloud Native Computing Foundation
◂ v1.0 available since 2015, currently at v1.18
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5. I ❤️ Docker - why k8s?
◂ I run
◂ Ok, I don’t, but all the cool kids run k8s !!
◂ My containers no longer fit to a single node
(true story bro)
Kubernetes enables to seamlessly run Docker
containers over multiple computing nodes
(as Docker Swarm does as well btw)
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6. Real World Example
™️
of complex system deployment
◂ 6 microservices (Spring Boot apps)
◂ 2 MySQLs (used by microservices)
◂ Kafka cluster (used by microservices)
◂ ElasticSearch cluster (used by microservices)
◂ Kibana (used by microservices)
◂ Zeebe workflow broker cluster
◂ Zeebe Operate + MySQL
◂ ElasticSearch cluster (used by Zeebe)
◂ Kibana (used by Zeebe)
~20 docker containers minimum, but
we need a highly available deployment..
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7. How do I get a k8s cluster?
◂ Minikube / Microk8s / K3s
Kubernetes on a single machine
◂ KOPS / kubeadm
Kubernetes on multiple machines
◂ AWS / Azure / Google Cloud
Managed Kubernetes in the cloud
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8. I have k8s.. Now
what?
#1 Set up the primary tools
◂ kubectl
Command line tool to manage k8s
◂ k9s (https://k9scli.io/)
The perfect GUI for k9s
#2 Start writing k8s YAML configs
#3 PROFIT
8

9. K8S Basic Objects
● Pod
wraps a Docker container
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● ReplicaSet
replicates a Pod
● Deployment
defines a ReplicaSet with other features (rolling update, etc)
● Service
Load balancer for a set of Pods
● Ingress
Enables inbound connections from outside k8s
● ConfigMap & Secret
Non-confidential and confidential configuration data
● PersistentVolume
Mountable volumes for persistent data

10. 10
K8S Basic Objects
visualized

11. 11
Kubernetes YAML config
➢ All K8S object types have YAML structures
➢ Configs describe the desired state
➢ Example:
○ Deploy nginx in 2 replicas
○ from Docker image
nginx:1.14.2
○ expose port 80

12. 12
DeployingaPod

13. Helm Charts
➢ Package manager for Kubernetes
nice concept, horrible name, horrible Go template format
➢ Wraps many k8s resources into a single package
➢ Manages dependencies between packages
(dependency tree structures)
➢ Tracks installed packages on k8s
➢ Values injection mechanism for custom
configuration 13

14. 14
Basic Helm commands
1. refresh dependent charts from Helm repos
$ helm dep up
2. Install package from chart
$ helm install <name> .
1. List installed packages
$ helm list
1. Upgrade deployed package
$ helm upgrade <name> .
1. Remove package (not complete removal!)
$ helm uninstall <name>

15. Helm package structure
■ templates/
K8s resources in the Chart
■ Chart.yaml
Chart definition file
■ requirements.yaml
Chart dependencies
■ values.yaml
Configuration values
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16. ExampleHelmchart
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17. “
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Summary
■ Kubernetes runs Docker containers over
multiple hosts
■ Everything on k8s is an Object
■ K8s objects are defined in YAML files
■ Helm charts deploy/upgrade multiple
k8s objects as single packages

18. 18
Thanks!
Any questions?
You can find me at:
◂ @kjozsa
◂ kristof.jozsa@gmail.com