OpenAPI Diff

A CLI tool to identify differences between Swagger or OpenApi specifications.

Requirements

• nodejs 10.x or higher (tested using 10.x, 12.x, 13.x and 14.x)
• npm 6.x or higher (tested using 6.x)
• Swagger 2 or OpenApi 3 specifications

Installation

Install the tool using npm and add it to the package.json

npm install openapi-diff --save-dev

Description

This tool identifies what has changed between two Swagger or OpenApi specification files. These changes are classified into three groups, breaking, non-breaking and unclassified. Using an approach based on set theory this tool is able to calculate these differences to a high level of accuracy.

Supported Keywords

SPEC_SUPPORT.md contains the details of what Swagger and OpenApi keywords are supported.

Change Classifications

Changes detected by this tool are classified into three groups.

Breaking

Changes that would make existing consumers incompatible with the API, for example:

• removing a path
• removing a method
• changing a property from optional to required in a request body
• changing a property from required to optional in a response body

Non Breaking

Changes that would not make existing consumers incompatible with the API, for example:

• adding a path
• adding a method
• changing a property from required to optional in a request body
• changing a property from optional to required in a response body

Unclassified

Changes that have been detected by the tool but can't be classified, for example:

• modifications to X-Properties

Usage

Usage as a cli tool

Invoke the tool with a file path to the source specification file and the destination specification file. These files should be in JSON or YAML format and be valid Swagger 2 or OpenApi 3 specificaitons.

The tool will output a list of breaking, non breaking and unclassified differences found between the source and desitnation files.

If any breaking changes are found the tool will return a non-zero exit code.

Example

/path/to/source-specification.yaml

openapi: 3.0.1
info:
  title: User Service
  version: 1.0.0
paths:
  /users:
    post:
      requestBody:
        content:
          application/json:
            schema:
              properties:
                name:
                  type: string
              required:
                - name
              type: object
        required: true
      responses:
        201:
          description: Created
          content:
            application/json:
              schema:
                properties:
                  id:
                    type: string
                required:
                  - id
                type: object
  /users/{userId}:
    get:
      parameters:
        - name: userId
          in: path
          required: true
          schema:
            type: string
      responses:
        200:
          description: The user
          content:
            application/json:
              schema:
                properties:
                  name:
                    type: string
                required:
                  - name
                type: object

/path/to/destination-specification.yaml

openapi: 3.0.1
info:
  title: User Service
  version: 1.0.0
paths:
  /users:
    post:
      requestBody:
        content:
          application/json:
            schema:
              properties:
                name:
                  type: string
              required:
                - name
              type: object
        required: true
      responses:
        201:
          description: Created
          content:
            application/json:
              schema:
                properties:
                  id:
                    type: string
                required:
                  - id
                type: object

Invoking the tool

openapi-diff /path/to/source-specification.yaml /path/to/destination-specification.yaml

Output

Breaking changes found between the two specifications:
{
    "breakingDifferences": [
        {
            "type": "breaking",
            "action": "remove",
            "code": "path.remove",
            "destinationSpecEntityDetails": [],
            "entity": "path",
            "source": "openapi-diff",
            "sourceSpecEntityDetails": [
                {
                    "location": "paths./users/{userId}",
                    "value": {
                        "get": {
                            "parameters": [
                                {
                                    "name": "userId",
                                    "in": "path",
                                    "required": true,
                                    "schema": {
                                        "type": "string"
                                    }
                                }
                            ],
                            "responses": {
                                "200": {
                                    "description": "The user",
                                    "content": {
                                        "application/json": {
                                            "schema": {
                                                "properties": {
                                                    "name": {
                                                        "type": "string"
                                                    }
                                                },
                                                "required": [
                                                    "name"
                                                ],
                                                "type": "object"
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            ]
        }
    ],
    "breakingDifferencesFound": true,
    "nonBreakingDifferences": [],
    "unclassifiedDifferences": []
}

Usage as a nodejs api

Invoke the library with a SpecOption for the source specification and the desitnation specification. A SpecOption has 3 properties:

| Name | Type | Required | Description | | ---------: | :------: | :------: | ------------------------------------------------------------ | | content | string | Yes | A string containing the serialised json or yaml content of the specification. | | location | string | Yes | A label for the specification, typically a file path or file name but can be any value. This is used when reporting errors parsing the specification content. | | format | string | Yes | The format of the specification. Must be either swagger2 or openapi3 |

For full details of the nodejs api please refer to api-types.d.ts

Example

const openapiDiff = require('openapi-diff');

const source = {
  // openapi3...
};

const destination = {
  // openapi3...
};

const result = await openapiDiff.diffSpecs({
  sourceSpec: {
    content: JSON.stringify(source),
    location: 'source.json',
    format: 'openapi3'
  },
  destinationSpec: {
    content: JSON.stringify(destination),
    location: 'destination.json',
    format: 'openapi3'
  }
});

if (result.breakingDifferencesFound) {
  console.log('Breaking change found!')
}

Changelog

See CHANGELOG.md

Contributing

See CONTRIBUTING.md

License

See LICENSE.txt