presentations/kubebuilder/content.md

Kubebuilder

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Content

• CRDs
• Controller / Operator
• Kubebuilder
• Live Coding
• Real Life Use Cases

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CRDs

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Controller

A control loop that watches the state [...] and makes changes attempting to move the current state towards the desired state.

• Kubernetes Glossary

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Controller

• integrated in kube-apiserver or kube-controller-manager
• watch builtin k8s objects (core, apps, batch)
• logic ontop of data
• create sub-resources

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Controller

deployment controller

• watches Deployments
• creates and deletes ReplicaSets
• scales ReplicaSets for rolling deployments

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Controller

kubelet

• watches PodSpecs
• starts/stops containers

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Operator

• term coined by CoreOS
• same as controller but for CRDs
• integrate operational knowledge
• provide usability features
  • updates
  • scaling
  • backups
  • integration with k8s

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Kubebuilder

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Live Coding

Check out the source at
https://github.com/apricote/kubebuilder-poke-sync

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Real Life Use Cases

Databases

• scaling
• configuration
• disaster recovery
• e.g. zalando/postgres-operator
• e.g. mongodb-enterprise-kubernetes

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Real Life Use Cases

Provisioning external resources

• call external APIs
• expose external state in cluster
• e.g. jetstack/cert-manager
• e.g. awslabs/aws-service-operator

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Real Life Use Cases

Application Lifecycle Managment

• deployment
• supervised updates
• health checking + alerts
• Helm Chart++
• e.g. gitlab-operator
• e.g. Tenant Operator