Continuous Delivery the hard way with Kubernetes
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This talk shows three increasingly advanced levels of continuous delivery with Kubernetes and GitLab (as an example), arguing for a continuous delivery architecture which has an explicit _Release Manager_ component. We then propose Flux, the open source project which powers the _Deploy_ feature of Weave Cloud, as an implementation of that idea. This approach is the precursor to GitOps.
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Continuous Delivery the hard way with Kubernetes
- 1. Continuous Delivery the hard way with Kubernetes Luke Marsden, Developer Experience @lmarsden
- 2. Agenda 1. Why should I deliver continuously? 2. Kubernetes primer 3. GitLab primer 4. “OK, so we’ve got these pieces, how are we going to put them together?” 5. Let’s iterate on a design! 6. Conclusions
- 3. Agenda 1. Why should I deliver continuously? 2. Kubernetes primer 3. GitLab primer 4. “OK, so we’ve got these pieces, how are we going to put them together?” 5. Let’s iterate on a design! 6. Conclusions
- 4. Why should I continuously deliver? • Microservices • Conway’s law • Scaling project, scaling team • Velocity!
- 5. Kubernetes: all you need to know Pods containers ServicesDeployments Container Image Docker container image, contains your application code in an isolated environment. Pod A set of containers, sharing network namespace and local volumes, co-scheduled on one machine. Mortal. Has pod IP. Has labels. Deployment Specify how many replicas of a pod should run in a cluster. Then ensures that many are running across the cluster. Has labels. Service Names things in DNS. Gets virtual IP. Two types: ClusterIP for internal services, NodePort for publishing to outside. Routes based on labels.
- 6. GitLab primer • Or you can use GitHub, Travis, Circle, Docker Hub, Quay.io, GCR… CI system Docker registry GitLab Version controlled code Version controlled code
- 7. Version controlled code These are the things that we’ve got Version controlled code CI system Docker registry Kubernetes clusterCode Docker image Kubernetes YAML
- 8. Version controlled code These are the things that we’ve got Version controlled code CI system Docker registry Kubernetes clusterCode Docker image Kubernetes YAML git git + shell docker registry API kubernetes API
- 9. These are the things that we’ve got Version controlled code CI system Docker registry Kubernetes clusterCode Docker image Kubernetes YAML
- 12. Version controlled code V1 architecture Version controlled code CI system Docker registry Kubernetes clusterkubectl apply -f service.yaml
- 13. V1 Deploy update (with CI system)
- 15. Version controlled code V1 architecture Version controlled code CI system Docker registry Kubernetes clustergit push master
- 16. Version controlled code V1 architecture Version controlled code CI system Docker registry Kubernetes clusterdocker build :a1b2c3
- 17. Version controlled code V1 architecture Version controlled code CI system Docker registry Kubernetes clusterdocker push :a1b2c3
- 18. Version controlled code V1 architecture Version controlled code CI system Docker registry Kubernetes clusterkubectl set image :a1b2c3
- 19. V1 Rollback
- 21. Version controlled code V1 architecture Version controlled code CI system Docker registry Kubernetes cluster git checkout master git revert HEAD git push
- 22. Version controlled code V1 architecture Version controlled code CI system Docker registry Kubernetes clusterdocker build :b2c3d4
- 23. Version controlled code V1 architecture Version controlled code CI system Docker registry Kubernetes clusterdocker push :b2c3d4
- 24. Version controlled code V1 architecture Version controlled code CI system Docker registry Kubernetes clusterkubectl set image :b2c3d4
- 26. Downsides • Building & pushing containers is slow (disk I/O, network), shouldn’t need to this when rolling back • Branch per environment required per microservice (explosion of branches, hard to manage & scale) • Only a matter of time until you get a git merge mess • Better to decouple version of code at HEAD from version deployed…
- 27. Version controlled configuration • users service • code for users service • Kubernetes YAML • orders service • code for orders service • Kubernetes YAML • config repo • Kubernetes YAML for users • Kubernetes YAML for orders • Version controlled config should be the source of truth for your whole app (all the microservices)
- 28. Decoupling versions from releases Code versions (branches, tags) Environments & releases • users service • master • feature_A • feature_B • orders service • master • feature_A • feature_B • … • production • users -> master @ t1 • orders -> master @ t1 • staging • orders -> master @ t2 • orders -> master @ t2 conflating per- service code branches with environments in each repo is a hack, and doesn’t scale well
- 29. V2 Put all the yamels in one place
- 30. Version controlled code V2 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Code Docker image Kubernetes YAML Have the CI system update the yamels automatically for you
- 31. Version controlled code V2 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Code Docker image Kubernetes YAML Have the CI system update the yamels automatically for you
- 32. Version controlled code V2 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Code Docker image Kubernetes YAML Have the CI system update the yamels automatically for you
- 33. Version controlled code V2 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Code Docker image Kubernetes YAML Have the CI system update the yamels automatically for you
- 34. Version controlled code V2 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Code Docker image Kubernetes YAML Have the CI system update the yamels automatically for you
- 35. Version controlled code V2 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Code Docker image Kubernetes YAML Have the CI system update the yamels automatically for you
- 36. Version controlled code V2 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Code Docker image Kubernetes YAML Have the CI system update the yamels automatically for you
- 37. Version controlled code V2 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Code Docker image Kubernetes YAML Have the CI system update the yamels automatically for you
- 38. Version controlled code Container builder demo Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Code Docker image Kubernetes YAML Have the CI system update the yamels automatically for you Builder used as CD system
- 39. Now you can recreate your production environment from the central YAML repository even if your entire production cluster gets deleted
- 40. Demo!
- 41. Downsides • The CI system is responsible for a lot now (design smell – overloaded) • You can only trigger the CI system by pushing code (we wanted to be able to rollback without pushing code) • If you rollback out of band (directly with kubectl), you have to remember to update the central configuration repo as well • Parallel builds can tread on eachothers’ toes, not atomic: race between git checkout and git push (need a global lock) • Scripting updates of yamels can be a pain… it mangles your yamels • Developers start asking for more release management features (rollback, pinning, automation for some envs and manual gating for others, and your once-simple script keeps growing…)
- 42. V3 Refactor architecture Add “release manager”
- 43. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy
- 44. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy
- 45. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy
- 46. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy
- 47. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy
- 48. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy
- 49. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy
- 50. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy
- 51. V3 Rollback doesn’t go via CI
- 52. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy rollback!
- 53. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy rollback!
- 54. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy rollback!
- 55. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy rollback!
- 56. Version controlled code V3 architecture Version controlled code CI system Docker registry Kubernetes cluster Version controlled config Release manager Code Docker image Kubernetes YAML push im age push config pull image list images pull, modify, push config push code policy rollback!
- 57. What does the release manager do? • Watches for changes in a container registry (output of CI system) • Makes commits for you to version controlled configuration (understands Kubernetes YAML) • Depending on release policy (per environment), either push changes continuously or permit manually gated releases • Allows releases to be rolled back by changing a pointer • Releases can be “locked” as a social cue
- 58. Different environments can have different release policies (no tight coupling between individual microservices repos and what’s released)
- 60. This is how we deploy Weave Cloud Weave Cloud helps devops iterate faster with: • observability & monitoring • continuous delivery • container networks & firewalls Weave Flux is a release manager for Kubernetes
- 61. Other topics • Kubernetes 101 • How do I monitor this stuff? (Prometheus) • Network policy for isolating & firewalling different microservices We have talks & trainings on all these topics in the Weave user group!
- 62. Join the Weave user group! meetup.com/pro/Weave/ Come hang out on Slack! weave.works/help
- 63. Thanks! Questions? We are hiring! DX in San Francisco Engineers in London & SF weave.works/weave-company/hiring Check out Flux on GitHub: github.com/weaveworks/flux