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29 lines
764 B
Markdown
29 lines
764 B
Markdown
## Declarative vs imperative in Kubernetes
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- With Kubernetes, we cannot say: "run this container"
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- All we can do is write a *spec* and push it to the API server
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(by creating a resource like e.g. a Pod or a Deployment)
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- The API server will validate that spec (and reject it if it's invalid)
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- Then it will store it in etcd
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- A *controller* will "notice" that spec and act upon it
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---
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## Reconciling state
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- Watch for the `spec` fields in the YAML files later!
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- The *spec* describes *how we want the thing to be*
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- Kubernetes will *reconcile* the current state with the spec
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<br/>(technically, this is done by a number of *controllers*)
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- When we want to change some resource, we update the *spec*
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- Kubernetes will then *converge* that resource
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