kubernetes-json-schema

Intro

HULL depends on the usage of the Kubernetes API JSON schema which can be generated by the Open API to JSON schema tool. This tool can generate a variety of JSON schema files when run against a particular Kubernetes API version, out of the tool results two things are required for a HULL release:

1. a full set of created JSON schemas which is used for validating the output of the internal tests against the Kubernetes API schema. This must be of the standalone-strict variety. These files are used to validate the test results against the API schemes.

2. a self-contained _definition.json with all the Kubernetes API objects of a particular version. This is the basis for HULL's values.schema.json

Single JSON schemas files

The first can best be obtained by cloning the following repository with up-to-date Kubernetes JSON schemas:

https://github.com/yannh/kubernetes-json-schema

This is an autoupated fork of the original project that provided the Kubernetes API JSON schemas but seems to be updated anymore. The fork creates new schemas on a regular schedule.

from this it is required to get the standalone-strict version of the relevant API version, for Kubenetes API version 1.32 this would be:

https://github.com/yannh/kubernetes-json-schema/tree/master/v1.32.0-standalone-strict

and all files therein need to be copied to the hull/files/test/HULL/schema folder.

The Git Repository is really big, if you don't want to clone the whole thing there is a helper site which lets you just download the needed folder:

https://download-directory.github.io/

All-in-one file JSON schema

The _definition.json may be taken from the https://github.com/yannh/kubernetes-json-schema projects output but the produced file lacks some enumeration values which are nice to have in the schema.

An alternative method to obtain a slightly better _definition.json is to produce it with the original tooling as such:

From https://github.com/instrumenta/kubernetes-json-schema/issues/26 repository holding Kubernetes JSON schemas, build according to: instrumenta/kubernetes-json-schema#26:

I worked around missing schemas for 1.19 by generating them on my own. This seems to work at first glance, although I don't have much prior experience with kubeval:

In Linux (or WSL):

# install tooling to generate the schemas
sudo apt install python-pip
export PYTHONHTTPSVERIFY=0 # this is only because I had cert issues
pip install openapi2jsonschema

# generate a folder with schema files for a specific version (1.19.3 in this case)
openapi2jsonschema -o "v1.19.3-standalone-strict" --kubernetes --stand-alone --strict https://raw.githubusercontent.com/kubernetes/kubernetes/v1.19.3/api/openapi-spec/swagger.json

# now fork this repo, add the generated files, commit, push

---

First install openapi2jsonschema with pip install openapi2jsonschema.

Then run the command with added --expanded switch to create all relevant files for the release (here v1.20.0):

openapi2jsonschema -o "v1.20.0-standalone-strict" --expanded --kubernetes --stand-alone --strict https://raw.githubusercontent.com/kubernetes/kubernetes/v1.20.0/api/openapi-spec/swagger.json

Note that this command might produce many errors like:

An error occured processing mutatingwebhook: URLError: <urlopen error [WinError 3] Das System kann den angegebenen Pfad nicht finden: '\\v1.22.0-standalone-strict\\_definitions.json'>

The created _definition.json cam now be used as source of the new hull/values.schema.json.