Kubernetes: pods and Deployments
The pod, the ReplicaSet and the Deployment, labels and selectors, the anatomy of a manifest, requests and limits, liveness and readiness probes, rolling updates and rollback.
- 30 cards
- 6 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
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A few cards from the deck
Pod: what is it?
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The smallest unit Kubernetes deploys: one or more containers that share the same network address and volumes, and live on the same node.
A pod is ephemeral: when it disappears, its controller replaces it with a new pod, with another address, instead of bringing the same one back.
Which pods does the selector
app=web,tier=frontcatch?
```text
p1 app=web tier=front
p2 app=web tier=back
p3 app=api tier=front
p4 app=web`- Only
p1 p1andp2p1andp3p1,p2andp4
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Only
p1The comma is an AND: both labels must be present with the right value.
p2has the wrongtier,p3the wrongapp, andp4has notierlabel at all.- Only
A Deployment manages …, one per version of the pod template; each one keeps the number of pods set by ….
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A Deployment manages ReplicaSets, one per version of the pod template; each one keeps the number of pods set by replicas.
During an update, the old ReplicaSet empties while the new one fills; the old one is kept, empty, for the rollback.
ReplicaSet: what is it?
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An object that keeps a given number of identical pods running, creating or deleting pods according to the gap it sees.
You rarely create one by hand: the Deployment manages one for each version of the pod template.