Yamlator

Yamlator is a CLI tool that allows a YAML file to be validated using a lightweight schema that defines the expected structure. When executed, the YAML is compared against the rules to validate that the relevant keys and data types are present. Once validated, a list of violations will be displayed to help amend the YAML file.

Installing the package

The Yamlator package can be installed from PyPi with:

pip install yamlator

A basic example

Schemas in Yamlator are comprised of rules, rulesets and enums, which are defined in a Yamlator schema file with the .ys extension.

In the Yamlator schema file, the entry point is defined in a schema block. As a minimum, a schema block must be defined for Yamlator to validate a file. Complex structures can be defined as rulesets to validate nested structures. For example, the following schema can be defined to manage a list of employees:

ruleset Employee {
    firstName str
    lastName str
    roles list(str) optional
}

schema {
    employees list(Employee)
}

This schema can then be used to validate the following YAML data:

employees:
    - firstName: employee
      lastName: one
      roles:
        - manager
    - firstName: employee
      lastName: two
      roles:
        - engineer
        - manager
    - firstName: employee
      lastName: three

More information on the different components that can be used in a schema can be found in the schema components documentation.

Additional examples of Yamlator schemas can be found in the examples directory

How to run the CLI

Assuming you have a YAML and Yamlator schema file, the CLI can be executed with:

yamlator <path-to-yaml-file> -s <path-to-yamlator-schema>

Where <path-to-yaml-file> is replaced with the path to your YAML file and <path-to-yamlator-schema> is the path to the schema file which must have the .ys extension.

The first argument for the CLI is always the path to the YAML file.

To see the help options for the CLI, run yamlator -h or yamlator --help

Setting up the development environment

For instructions on how to set up the development environment, read the setting up the environment documentation.