OpenApi Tools: OpenAPI Style Validator

A customizable style validator to make sure your OpenApi spec follows your organization's standards.

Summary

Unless you are working alone on a very small API, you are probably working with other people on your spec (YAML) file. Even if you have written directions and standards in a shared PDF or on a wiki somewhere and sent it to all the team members, there is no way to be sure they will follow it.

You could argue that you will do code review to prevent these errors. Yes you could but wouldn't it be better if you could automatize all of this? You can still do code reviews to find business/requirements/REST path errors but let openapi-style-validator validate the style and standards like mandatory examples, naming conventions, description, etc...

What it can validate

API Info

• API license must be present and non-empty string
• API description must be present and non-empty string
• API contact must be present and non-empty string

Operations

• OperationId must be present and non-empty string
• Operation description must be present and non-empty string
• Operation must have a tag and non-empty string
• Operation summary must be present and non-empty string

Models

• All model properties must have examples
• All model properties must have descriptions
• All required properties must be listed among the properties

Naming convention

• Enforce naming convention for paths, parameters (path, query and cookie), headers and properties
  • underscore_case
  • UNDERSCORE_UPPER_CASE
  • camelCase
  • hyphen-case
  • Hyphen-Upper-Case

Paid Alternatives

This project was started because when I tried SwaggerHub (which is the paid version of the swagger toolkit), they had something similar, but it was proprietary. I didn't want to pay for the service so I created this project in my free times. I did not validate lately if they still have this feature.

How to use the style validator

For now, the project is a simple command line interface (CLI) and a library. The easiest way to use it right now is to use the CLI and check the output. It will list all errors found based on the options you provided.

To build

The project is configured to use gradle. To build the jar, just do:

gradlew assemble

or if you want to invoke the jar creation directly

gradlew shadowJar

To change the code

If you want to open the project, I highly suggest that you use IntelliJ IDEA Community (Free) or Ultimate (paid). This IDE is cross platform so it should work on any OS. This project was created using this tool and you can just open it directly. Maybe you can use other tools to open the project but I will not provide any support.

To launch

java -jar openapi-style-validator.jar -s ./path/to/spec.yaml -o ./path/to/options.json

Example using the default output path for the jar (replace <version> with the current version):

java -jar modules/cli/build/libs/openapi-style-validator-cli-<version>-all.jar -s specs/petstore.yaml -o specs/options.json

Command Line

Options File

The options file is described in json (example in specs/options.json), and has the following possible values:

Parameter Naming Convention hierarchy

The Parameter Naming Convention can be defined by a combination of the following options in the options.json file:

• parameterNamingConvention
• pathParamNamingConvention
• queryParamNamingConvention
• cookieParamNamingConvention

The first option (parameterNamingConvention) defines a global convention for all other parameter naming convention options (path, query and cookie), unless they are explicitly defined in the options.json file.

In other words, the pathParamNamingConvention, queryParamNamingConvention and cookieParamNamingConvention are specific for the parameter type their names indicate. Thus, they take precedence over parameterNamingConvention when they are defined. If not defined, the undefined option is assigned the same value for parameterNamingConvention (either explicitly defined or default).

Example 1:

{
  /*
    'parameterNamingConvention' is not defined.
        Then it assumes the 'CamelCase' convention.
   */
  "pathParamNamingConvention": "UnderscoreCase",
  "queryParamNamingConvention": "HyphenCase"
  /*
    'cookieParamNamingConvention' is not defined.
        Then it assumes the same value as 'parameterNamingConvention',
        which is its default value ('CamelCase').
   */
}

Example 2:

{
  "parameterNamingConvention": "HyphenCase",
  "pathParamNamingConvention": "UnderscoreCase",
  "queryParamNamingConvention": "HyphenCase"
  /*
    'cookieParamNamingConvention' is not defined.
        Then it assumes the same value as 'parameterNamingConvention',
        which is explicitly defined as 'HyphenCase'.
   */
}

Supported Extensions

We sometimes have some paths in our API that are there for legacy reasons. To support this scenario, there is now the possibility to add an extension property in your spec named x-style-validator-ignored. Here is an example:

/my-pathWithWeird_NAMING-FoRLeGaCyReAsOnSLOL:
  x-style-validator-ignored: true
  post:
    tags:
      - Whatever
    summary: A summary
    /* missing operating id or other important property */
    responses:
      200:
        description: OK
  get:
    ...

The path (GET, POST, etc..) will be completely ignored by the style validator.

Roadmap

To view the latest version of the roadmap, please see the official roadmap.

Releases on maven central

The different components of this project are released on Maven Central:

The core library:

<dependency>
  <groupId>org.openapitools.openapistylevalidator</groupId>
  <artifactId>openapi-style-validator-lib</artifactId>
  <version>${validatorVersion}</version>
</dependency>

The command line tool (without dependency):

<dependency>
  <groupId>org.openapitools.openapistylevalidator</groupId>
  <artifactId>openapi-style-validator-cli</artifactId>
  <version>${validatorVersion}</version>
</dependency>

The command line tool is also available as standalone jar (containing its dependencies):

<dependency>
  <groupId>org.openapitools.openapistylevalidator</groupId>
  <artifactId>openapi-style-validator-cli</artifactId>
  <version>${validatorVersion}</version>
  <classifier>all</classifier>
</dependency>

You can download it manually (replace the <version> placeholder in following URL):

https://repo1.maven.org/maven2/org/openapitools/openapistylevalidator/openapi-style-validator-cli/<version>/openapi-style-validator-cli-<version>-all.jar