Custom Resources for Cloud Native DevOps

In this talk Jelmer will share with you what Kubernetes' Custom Resources exactly are and how they can help reduce YAML boilerplate. You'll learn how to create an Operator from scratch which you can use to automate DevOps tasks in a CloudNative manner.

Transcript

1. Custom Resources for Cloud Native DevOps
2. FIND ME github.com/jelmersnoeck twitter.com/jelmersnoeck Jelmer Snoeck ABOUT ME - OX Tech Lead at manifold.co - Kubernetes - Terraform - Kubelist Editor
3. $ tree custom-resources-cloud-native-devops/ - What are Custom Resources - How to build Custom Resources - Publishing Custom Resources
4. Custom Resource (Definitions) Photo by The Roaming Platypus on Unsplash
5. A custom resource is an extension of the Kubernetes API that is not necessarily available on every Kubernetes cluster. In other words, it represents a customization of a particular Kubernetes installation.
6. Custom Resource Definition (CRD)
7. The CustomResourceDefinition API resource allows you to define custom resources. Defining a CRD object creates a new custom resource with a name and schema that you specify. The Kubernetes API serves and handles the storage of your custom resource.
11. Validation
12. Open API Schema
16. Admission Webhooks
17. Printer Columns
20. Finalizers
21. Controller vs Operator
22. Controller <> Operator - Controller purely interacts with k8s objects (even custom ones) - Operator knows about a different domain outside of k8s (etcd, prometheus, …)
23. Some CRDs in the wild
24. - cert-manager - prometheus-operator - ingress-nginx-controller - contour - ingress-monitor - istio Examples
25. What’s under the hood Photo by Wade Lambert on Unsplash
26. Defining APIs
27. API Definitions
29. Generated runtime.Object code
30. type Object interface { GetObjectKind() schema.ObjectKind DeepCopyObject() Object }
32. Scheme Definitions
35. Generating Clients
36. k8s.io/code-generator/generate-groups.sh
38. ./vendor/k8s.io/code-generator/generate-groups.sh \ all \ github.com/jelmersnoeck/ingress-monitor/pkg/client/generated \ github.com/jelmersnoeck/ingress-monitor/apis \ ingressmonitor:v1alpha1 \ --go-header-file boilerplate.go.txt
42. Controller
43. Cache Informers
46. Event Handlers
47. type ResourceEventHandler interface { OnAdd(obj interface{}) OnUpdate(oldObj, newObj interface{}) OnDelete(obj interface{}) }
50. Workqueue
51. Built in queue features • Fair: items processed in the order in which they are added. • Stingy: a single item will not be processed multiple times concurrently, and if an item is added multiple times before it can be processed, it will only be processed once. • Multiple consumers and producers. In particular, it is allowed for an item to be reenqueued while it is being processed. • Shutdown notifications.
55. Label Selectors
56. Labels
63. Survive Rescheduling
65. Testing
66. Testing - Fake Clients - Add wrappers to test informers - Use of testing.Fake Actions
67. Publishing Photo by chuttersnap on Unsplash
68. RBAC
69. Survive Rescheduling
70. Validation
71. Resource Utilization
72. Application Structuring
73. Observability
74. Thanks! Questions? @jelmersnoeck manifold.co