¬ just serendipity 🍀 (not just serendipity)

YAML files can have a schema associated to them.

Schema store is a popular source for schemas. Or you could write your own.

JSON Schemas work on YAML files just fine.

Let’s say you found a schema. For example, for JSON Patch.

Assume this sample .yaml file:

- op: remove
  path: /spec/syncPolicy/automated

How to enforce the schema above in CI?

One approach I like is with YAML Language Server by Red Hat.

You start by annotating the file with the desired schema:

# yaml-language-server: $schema=https://json.schemastore.org/json-patch.json
- op: remove
  path: /spec/syncPolicy/automated

And then you integrate it with a CI tool that is aware of it. I like pre-commit.com. Assuming you follow the pre-commit setup, integrate the hook:

repos:
  - repo: https://github.com/jmlrt/check-yamlschema
    rev: v0.0.4
    hooks:
      - id: check-yamlschema

Then pre-commit run [--all-files] check-yamlschema shall perform its job.

https://github.com/jmlrt/check-yamlschema:

A CLI and pre-commit hook for jsonschema validation in YAML files with multiple documents

Parse multi-documents YAML files, look for inline schema comments, and validate the documents according to their schema.

The ‘any’ schema¹ can be handy as an opt-out mechanism:

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://json.schemastore.org/any.json",
  "anyOf": [
    { "type": "object" },
    { "type": "array" },
    { "type": "string" },
    { "type": "number" },
    { "type": "boolean" },
    { "type": "null" }
  ]
}