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112 lines
2 KiB
Markdown
112 lines
2 KiB
Markdown
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# Kubebuilder
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---
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### Content
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- CRDs
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- Controller / Operator
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- Kubebuilder
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- Live Coding
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- Real Life Use Cases
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---
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## CRDs
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---
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## Controller
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> A **control loop** that watches the state [...] and makes changes attempting to move the **current state towards the desired state**.
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- [Kubernetes Glossary](https://kubernetes.io/docs/reference/glossary/?fundamental=true#term-controller)
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--
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## Controller
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- integrated in `kube-apiserver` or `kube-controller-manager`
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- watch builtin k8s objects (`core`, `apps`, `batch`)
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- logic ontop of data
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- create sub-resources
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--
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## Controller
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### deployment controller
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- watches `Deployments`
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- creates and deletes `ReplicaSets`
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- scales `ReplicaSets` for rolling deployments
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--
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## Controller
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### kubelet
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- watches `PodSpecs`
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- starts/stops containers
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--
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## Operator
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- term coined by CoreOS
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- same as controller but for CRDs
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- integrate operational knowledge
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- provide usability features
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- updates
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- scaling
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- backups
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- integration with k8s
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---
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## Kubebuilder
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---
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## Live Coding
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Check out the source at
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https://github.com/apricote/kubebuilder-poke-sync
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---
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## Real Life Use Cases
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### Databases
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- scaling
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- configuration
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- disaster recovery
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- e.g. [zalando/postgres-operator](https://github.com/zalando/postgres-operator)
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- e.g. [mongodb-enterprise-kubernetes](https://github.com/mongodb/mongodb-enterprise-kubernetes)
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--
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## Real Life Use Cases
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### Provisioning external resources
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- call external APIs
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- expose external state in cluster
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- e.g. [jetstack/cert-manager](https://github.com/jetstack/cert-manager)
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- e.g. [awslabs/aws-service-operator](https://github.com/awslabs/aws-service-operator)
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--
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## Real Life Use Cases
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### Application Lifecycle Managment
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- deployment
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- supervised updates
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- health checking + alerts
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- Helm Chart++
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- e.g. [gitlab-operator](https://gitlab.com/charts/components/gitlab-operator)
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- e.g. [Tenant Operator](https://blog.kolide.com/using-a-kubernetes-operator-to-manage-tenancy-in-a-b2b-saas-app-250f1c9416ce)
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