Pods: The Basic Deployment Unit

Foundations / Guide 4 of 103 / Beginner

• Kubernetes1.36.4
• Cluster4 nodes
• Runtimecontainerd 2.2.6
• CNICalico v3.32.1
• TimeAbout 30 min

UIDs, resourceVersions, timestamps and pod addresses are generated per run. The manifests are the part to copy.

This guide includes

Use this when you are moving from containers to Kubernetes and need to know what a Pod adds. This matters because Kubernetes does not run containers, it runs Pods - and the network and storage shared inside one is the whole reason the abstraction exists.

• creating a Pod with kubectl run and reading back everything the API server filled in
• writing the manifest yourself instead, and labelling it so Services and controllers can find it
• running two containers in one Pod and proving they share a volume, with readOnly enforced
• confirming the Pod has one address that both containers share
• deleting a bare Pod and finding that nothing brings it back

Before you start

• A working cluster and kubectl configured against it.
• Any container experience helps, but is not required. If you know docker run, the interesting part is what Kubernetes adds around it.
• A scratch namespace if you are on a shared cluster. Everything here runs in default and is deleted at the end.

1. 1

   The smallest thing you can run

2. 2

   See what the API server added

3. 3

   Write the manifest yourself

4. 4

   Labels are the addressing system

5. 5

   Two containers, one Pod

6. 6

   Prove they share the volume, and that readOnly means it

7. 7

   One address for the whole Pod

8. 8

   A bare Pod does not come back

9. 9

   Clean up

Official sources

• Pods
• Labels and selectors
• Resource management for pods and containers
• Sidecar containers