kubeconform: Mount Schema Example #

Related Examples:

Overview #

If you want to use your own schema instead of the built-in schema, you can follow this example.

This example demonstrates how to mount a local schema directory and then use it with kubeconform 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/tree/master/examples/kubeconform-mount-schema

We have a ReplicationController in replicationcontroller.yaml that has a schema violation:

  • spec.replicas must not be a string.

We have a jsonschema directory that contains some json schema files that will be used with kubeval function.

Schema #

The json schema used in this example are converted from an openapi schema file using openapi2jsonschema. We run the following command to do it:

$ openapi2jsonschema --stand-alone --expanded --kubernetes -o jsonschema path/to/openapi.json

Function invocation #

We can invoke function with the following command:

$ kpt fn eval kubeconform-mount-schema -i ghcr.io/kptdev/krm-functions-catalog/kubeconform:latest --results-dir /tmp \
  --mount type=bind,src="$(pwd)/kubeval-mount-schema/jsonschema",dst=/schema-dir/master-standalone \
  -- schema_location=file:///schema-dir

We mount the local schema directory into the container with path /schema-dir/master-standalone. And then we tell the function the location of the schema by specifying schema_location=file:///schema-dir. The function will by default look for the master-standalone directory in the specified schema_location.

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/kubeconform:latest
    stderr: 'failed to evaluate function: error: function failure'
    exitCode: 1
    results:
      - message: got string, want null or integer
        severity: error
        resourceRef:
          apiVersion: v1
          kind: ReplicationController
          name: bob
        field:
          path: spec.replicas
        file:
          path: replicationcontroller.yaml

To fix the violation, replace the value of spec.replicas with an integer

Rerun the command, and it should succeed.