Kubernetes 101: A gentle introduction

An introduction to Kubernetes, as the home for your microservices, presenting the main Kubernetes concepts.

Transcript

1. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete A HOME FOR YOUR MICROSERVICES: K8S
2. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete BORING 2
4. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete A HOME FOR YOUR MICROSERVICES: K8S KATE’S Woohoo!! click-bait title!!
5. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete OUR GOAL FOR TODAY 5
6. +
8. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete A HOME FOR YOUR CODE 8
9. PODS … NOT !!
10. PODS
11. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete WORDPRESS_POD.YAML 11 metadata: labels: app: wordpress tier: frontend spec: containers: - image: wordpress:4.8.0-apache name: wordpress env: - name: WORDPRESS_DB_HOST value: wordpress-mysql - name: WORDPRESS_DB_PASSWORD value: a super secure password for my mysql 1 Labels: for reporting + 
 linking to other components Docker image env vars
12. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete 12 A HOME FOR YOUR CONFIG
13. >> Yorgos Saslis | @gsaslis |DevStaff Meetup, Heraklion, Crete CONFIG MAPS 13 kind: ConfigMap apiVersion: v1 metadata: name: logstash-config namespace: default data: log4j2_properties: |- status = error name = LogstashPropertiesConfig appender.console.type = Console appender.console.name = plain_console appender.console.layout.type = PatternLayout appender.console.layout.pattern = [%d{ISO8601}][%-5p][%-25c] %m%n rootLogger.level = FATAL rootLogger.appenderRef.console.ref = ${sys:ls.log.format}_console definition data
14. >> Yorgos Saslis | @gsaslis |DevStaff Meetup, Heraklion, Crete SECRETS 14 apiVersion: v1 kind: Secret metadata: name: wordpress-pass type: Opaque data: password.txt: #base64 encoded 1. DEFINE env: - name: WORDPRESS_DB_PASSWORD valueFrom: secretKeyRef: name: wordpress-pass key: password.txt env: - name: WORDPRESS_DB_HOST value: wordpress-mysql - name: WORDPRESS_DB_PASSWORD value: a super secure password… 2. USE
15. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete A HOME FOR YOUR NETWORK 15
16. >> Yorgos Saslis | @gsaslis |DevStaff Meetup, Heraklion, Crete SERVICES 16
17. >> Yorgos Saslis | @gsaslis |DevStaff Meetup, Heraklion, Crete SERVICES 17 Provide Internal Load-Balancing Distribute traffic to Pods with specific labels Port mappings Can be bound to external Load Balancer (AWS ELB/ ALB, Google LB, etc.)
18. >> Yorgos Saslis | @gsaslis |DevStaff Meetup, Heraklion, Crete PORTS 18 spec: containers: - image: wordpress:4.8.0-apache name: wordpress ports: - containerPort: 80 name: wordpress define ports on container
19. >> Yorgos Saslis | @gsaslis |DevStaff Meetup, Heraklion, Crete SERVICES 19 apiVersion: v1 kind: Service metadata: name: wordpress labels: app: wordpress spec: ports: - port: 80 selector: app: wordpress tier: frontend type: LoadBalancer bind to pods ports the service listens on ( )
20. >> Yorgos Saslis | @gsaslis |DevStaff Meetup, Heraklion, Crete SERVICES 20 http://wordpress:80 Wordpress Pod 1 Wordpress Pod n …
21. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete 21 A HOME FOR YOUR STORAGE
22. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete VOLUMES “Same” as docker volumes Same lifecycle as Pod. Persists across restarts. Not same lifecycle as Container. Works fine on “localhost”. 22 apiVersion: v1 kind: Pod metadata: name: test-pd spec: containers: - image: gcr.io/google_containers/ test-webserver name: test-container volumeMounts: - mountPath: /cache name: cache-volume volumes: - name: cache-volume emptyDir: {}
23. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete PERSISTENT VOLUMES Persist across nodes. Lifecycle outlasts pod. 23 spec: containers: - image: wordpress:4.8.0-apache name: wordpress volumeMounts: - name: wordpress-persistent-storage mountPath: /var/www/html volumes: - name: wordpress-persistent-storage persistentVolumeClaim: claimName: wp-pv-claim
24. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete A HOME FOR YOUR WORK(LOAD) 24
25. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete JOBS A job creates one or more pods and ensures that a specified number of them successfully terminate. As pods successfully complete, the job tracks the successful completions. When a specified number of successful completions is reached, the job itself is complete. Use cases: long-running background jobs (e.g. migrations, cleanups, etc.) 25
26. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete DEPLOYMENT Uses ReplicaSets / ReplicationController Ensures a specified number of pod replicas are running at any one time. Homogeneous pods, always up and available. (if one crashes, starts a new one). Supports rolling updates. Canary updates possible through Deployments. 26
27. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete STATEFUL SET identical container spec, but unique identity for each pod ordinal index stable network id stable storage Deployment guarantees: Pods created sequentially, in order, from {0..N-1}. Pods are terminated in reverse order, from {N-1..0}. Before scaling, all predecessors must be Running and Ready. Before termination, all successors must be completely shutdown. 27
28. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete DAEMON SET Ensures that all (or some) Nodes run a copy of a Pod. Some typical uses of a DaemonSet are: cluster storage daemon, such as glusterd, ceph, on each node. logs collection daemon on every node, such as fluentd or logstash. node monitoring daemon, such as Prometheus Node Exporter, collectd, Datadog agent, New Relic agent, or Ganglia gmond. 28
29. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete SO, BACK TO WORDPRESS… 29
30. >> Yorgos Saslis | @gsaslis | DevStaff Meetup, Heraklion, Crete 30
31. >> Yorgos Saslis | Software Developer | @gsaslis THANK YOU! 31 Yorgos Saslis
 @gsaslis
 github.com/gsaslis