kubeval: Imperative Example #

Overview #

This example demonstrates how to imperatively invoke kubeval function to validate KRM resources.

Fetch the example package #

Get the example package by running the following commands:

$ kpt pkg get https://github.com/kptdev/krm-functions-catalog.git/examples/kubeval-imperative

We have a ReplicationController in app.yaml that has 2 schema violations:

.spec.templates is unknown, since it should be .spec.template.
spec.replicas must not be a string.

Function invocation #

Try it out by running the following command:

# We set `strict=true` to disallow unknown field and `skip_kinds=MyCustom,MyOtherCustom` to skip 2 kinds that we don't have schemas.
$ kpt fn eval kubeval-imperative --image ghcr.io/kptdev/krm-functions-catalog/kubeval:latest --results-dir /tmp -- strict=true skip_kinds=MyCustom,MyOtherCustom

The key-value pair(s) provided after -- will be converted to ConfigMap by kpt and used as the function configuration.

Expected Results #

Let’s look at the structured results in /tmp/results.yaml:

apiVersion: kpt.dev/v1
kind: FunctionResultList
metadata:
  name: fnresults
exitCode: 1
items:
  - image: ghcr.io/kptdev/krm-functions-catalog/kubeval:latest
    exitCode: 1
    results:
      - message: Additional property templates is not allowed
        severity: error
        resourceRef:
          apiVersion: v1
          kind: ReplicationController
          name: bob
        field:
          path: templates
        file:
          path: app.yaml
      - message: 'Invalid type. Expected: [integer,null], given: string'
        severity: error
        resourceRef:
          apiVersion: v1
          kind: ReplicationController
          name: bob
        field:
          path: spec.replicas
        file:
          path: app.yaml

To fix them:

replace the value of spec.replicas with an integer
change templates to template

Rerun the command, and it should succeed.