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Using kubernetes to lose your fear of using containers
- 1. Using kubernetes to lose your fear of using containers Jose Fuentes - jfuentes@bitnami.com Toolchain Engineer @_jsfuentes
- 2. Kubernetes - Run containers on a cluster - Automatic deployment - Scaling - Designed for failure Health checking And other cool features Manage containerized application Load balancing Rolling updates Replication
- 3. Kubernetes - Run containers on a cluster - Automatic deployment - Scaling - Designed for failure Health checking And other cool features Manage containerized application Load balancing Rolling updates Replication Implies a contract with the applicationImplies a contract with the application
- 4. It sounds interesting. Tell me more. - Must-know concepts for understanding kubernetes - How my app should be to take advantage of all the features - And some other interesting things for operating apps with k8s log management debugging health checking failure recovery monitoring metering updating
- 6. Architecture kubectl Master Controller Manager Scheduler etcd Kubernetes API Minion docker engine pod kube-proxykubelet pod Minion docker engine pod kube-proxykubelet pod firewall/ loadbalancer/ proxy Top view
- 7. Minion 1 - Collection containers - Unit of scheduling and replication - Ephemeral, not durable - They’re replaced, not resurrected - Containers in the same pod share: - PIDs - Network - Hostname Kubernetes Master Pod Container A Container B Minion 2 Minion 1 Pod PodContainer C Container D Components Pods
- 8. - - - - Services Types You can’t communicate with pods directly Components Services services allows to route traffic to a set of pods http://railsapp:3000 Minion 1 kube-proxy pod Minion 2 kube-proxy pod service Cloud Provider LoadBalancer
- 9. - - - - Services Types You can’t communicate with pods directly Components Services services allows to route traffic to a set of pods Minion 1 kube-proxy pod Minion 2 kube-proxy pod http://minion1:3000 http://minion2:3000
- 10. - - - - Services Types You can’t communicate with pods directly Components Services services allows to route traffic to a set of pods Minion 1 kube-proxy pod Minion 2 kube-proxy pod service Cloud Provider LoadBalancer http://<public IP>
- 11. - - - - Services Types You can’t communicate with pods directly Components Services services allows to route traffic to a set of pods ExternalName external.service.com internalname
- 12. - Arbitrary metadata attached to any object - key-value pairs - Relevant attributes for users - Allows to organize objects in the cluster Labels Selectors - Identify a set of objects based on labels values app: myapp role: web branch: prod app: myapp role: db branch: prod app: myapp role: web branch: dev app: myapp role: db branch: dev branch == prod branch == dev Labels and selectors
- 15. CLI and UI
- 16. - Manage several clusters and contexts - Get cluster info: nodes, pods, services, deployments - Deploy/delete stuff - Scale up/down (replicas) - Interact with containers - See logs - Create tunnels (port forwarding) Kubectl CLI http://kubernetes.io/docs/user-guide/docker-cli-to-kubectl/
- 17. Kubectl UI (dashboard) http://kubernetes.io/docs/user-guide/ui/ It runs in a pod!
- 18. How an app should be to work well on k8s
- 19. Let me tell you a secret...
- 20. Kubernetes is not for everybody
- 21. Wishlist Restart should not be a pain Your app is gonna be restarted often, so… stay prepared for that - Start fast - Don't cook assets at boot time - Don't lose data on reboots
- 22. Wishlist Data should be separated Your app should be stateless. The state should be stored apart. uploaded files sessions info plugins jobs Oh man, that's easy. I mount a volume for my mariaDB and I am done. It is not just the DB
- 23. Wishlist Data schema compatible across versions - That's not possible... - Well… at least do changes in a clever way - Temporary maintain datastore compatible with two versions - B/C changes - Intermediate migrations - Make logic to adapt API requests to the new format
- 24. Example: Drupal blog Database Web server Drupal php code v8.1 plugin Web server Drupal php code v8.2 Web server Drupal php code v8.1 plugin
- 25. Example: Drupal blog Database Web server Drupal php code v8.1 Web server Drupal php code v8.2 External volume Web server Drupal php code v8.1 plugin
- 27. A pet server -You instantiated it time ago -Then you manually installed thing you needed there -You ssh it often because you like to manually check things there -Eventually you go there and do some manual work to install something -Now you have an adorable pet that you really worry about because it's something unique
- 28. We want cattle servers They are almost identical Easily replaceable DON'T SSH
- 29. Manos a la obra!
- 30. Our app Container web :3000 Container mongo :27017 josefuentes/todolist docker build + docker push bitnami/mongodb Container images
- 31. Our app Deployment info for kubernetes Service LoadBalancer Pod :80 Container web :3000 Service ClusterIP Pod Container mongo :27017 :27017 - Be aware of your app limitations tier=web tier=db - Be tidy, use labels - Be precise, set probes replicas high availability configs info stored in host - If you know very well your app, limit the resources
- 32. Debug Gimme a shell!!! List the pods Use exec kubectl get pods kubectl exec -ti <mypod> -c <container> bash
- 33. Debug See logs Use logs kubectl logs <mypod> -c <container> TIP: use -f kubectl logs -f <mypod> -c <container>
- 34. Debug Forward a port Use logs kubectl logs <mypod> -c <container> TIP: use -f kubectl port-forward <mypod> [local_port:]remote_port
- 36. Failure recovery Inside pods -> restart policies In machines -> pods reallocation
- 37. Pod Container 1 Container 2 RestartPolicy: Always Pod Container 2Container 1 Pod Container 2Container 1 Failure recovery
- 38. Pod Container 1 Container 2 Pod Container 2Container 1 Pod Container 2Container 1 Pod Container 2Container 1 Successful RestartPolicy: OnFailure Failure recovery
- 39. Pod Container 1 Container 2 Pod Container 2Container 1 Pod Container 2Container 1 Failed Pod Container 2Container 1 Successful RestartPolicy: Never Failure recovery
- 40. Scale replicas Several instances of a pod - Same configuration - Normally on different machines - LoadBalancing - Better redundancy
- 41. Scale replicas There are many ways of scaling your app. It is important how do you design your pods Pod Apache Express Pod mongoDBService DB
- 42. Scale replicas There are many ways of scaling your app. It is important how do you design your pods Pod mongoDBService DB Pod Apache Express Pod Apache Express
- 43. Scale replicas There are many ways of scaling your app. It is important how do you design your pods Pod mongoDBService DB Pod Express Pod Apache Pod Apache
- 44. Advanced log monitoring http://kubernetes.io/docs/getting-started-guides/logging-elasticsearch/ Pods are ephemeral -> logs are not going to be there forever Solution -> log live ingestion Pod
- 45. Pod version=1 Pod version=1 Pod version=1 Pod version=1 Service LoadBalancer Pod version=2 Pod version=2 $ kubectl set image deploy <your deploy> <container>=<image> Rolling out new features
- 46. Thank You