LearningKubernetes-CodeLabs

Kubernetes Resource Model (KRM)

Kubernetes has a uniform Resource Model for all interactions you’ll have with its API - the KRM. Let’s explore it:

1. Get rid of the initial hello, world:

   k delete deployment echoserver
   

2. Glance at, and then apply, the echo.pod.yaml resource of kind: Pod:

   k apply -f https://raw.githubusercontent.com/vorburger/LearningKubernetes-CodeLabs/develop/docs/files/echo.pod.yaml
   

3. You now have a Pod running. Let’s list it, look at its log, and look at it’s YAML:

   k get pods
   k logs echoserver
   k get pod echoserver -o yaml
   

   Note how the YAML shown is an extended version of the echo.pod.yaml, which we applied above, now with:

   • some new metadata (like a creationTimestamp or a uid)
   • additional spec (like system defaults; we could override those)
   • the status, which Kubernetes added when it reconciled the desired state (AKA intent) expressed by the spec with the system’s observed state

4. This Pod is a (built-in) KRM API resource “kind” (type). We can see all of them like this:

   k api-resources
   k api-versions
   

5. We can learn more about each of them, as well as detailed documentation about the respective resource’s fields:

   k explain pod
   k explain pod.spec.containers.image
   

6. Clean up:

   k delete pod echoserver
   

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