OAS Validator | 中文

OpenAPI V3 Spec validation tools.

Project structure

• oas-validator-core: core apis and skeletons implementations
• oas-validator-core-spring: Spring Boot Starter for core skeletons
• oas-validator-test: test helpers for core api
• oas-validator-style: check style validators
• oas-validator-compatibility: compatibility validators
• oas-validator-compatibility-spring: Spring Boot Starter for compatibility validators
• oas-validator-web: web ui

Style checking

OAS must compatible with OAS 3.0.2, besides must obey the following rules.

String patterns

• lower-camel-case: initial letter lowercase camel case, regex is ^[a-z]+((\d)|([A-Z0-9][a-z0-9]+))*([A-Z])?$
• upper-camel-case: initial letter uppercase camel case, regex is ^[A-Z]([a-z0-9]+[A-Z]?)*$
• upper-hyphen-case: initial letter uppercase, multiple words concat with -, such as Content-Type, Accept, X-Rate-Limit-Limit, regex is ^([A-Z][a-z0-9]*-)*([A-Z][a-z0-9]*)$

Rules properties file

Below is a style-check-rule.properties example:

#######################
# OpenAPI Object
#######################
# openapi property must be 3.0.x and >= 3.0.2
openAPI.openapi.gte=3.0.2
# tags property size should >= 1
openAPI.tags.size.gte=1
# security property size must == 0
openAPI.security.size.eq=0

#######################
# Info Object
#######################
# description property is required
info.description.required=true

#######################
# Tag Object
#######################
# name property, must be upper-camel-case
tag.name.case=upper-camel-case
# tag should be referenced by at least one Operation Object
tag.name.must_be_referenced=true
# description property, required
tag.description.required=true

#######################
# Paths Object
#######################
# path must be lower-camel-case, including Path Templating variable
paths.key.case=lower-camel-case

#######################
# Operation Object
#######################
# summary property, required
operation.summary.required=true
# operationId property, must be lower-camel-case
operation.operationId.case=lower-camel-case
# tags property, size must == 1
operation.tags.size.eq=1
# all tags should references which are defined in $.tags
operation.tags.element.must_reference_root_tags=true
# servers property, size must == 0
operations.servers.size.eq=0

#######################
# Parameter Object
#######################
# description property, required
parameter.description.required=true
# name property, for header parameter, must be upper-hyphen-case
parameter.name.header.case=upper-hyphen-case
# name property, for cookie parameter, must be lower-camel-case
parameter.name.cookie.case=lower-camel-case
# name property, for path parameter, must be lower-camel-case
parameter.name.path.case=lower-camel-case
# name property, for query parameter, must be lower-camel-case
parameter.name.query.case=lower-camel-case

#######################
# RequestBody Object
#######################
# description property, required
requestBody.description.required=true

#######################
# Response Object
#######################
# headers property's key must be upper-hyphen-case
response.headers.key.case=upper-hyphen-case

#######################
# Schema Object
#######################
# title property, required if parent is Schema Object or Components Object
schema.title.required=true
# properties property, name(properties key) must be lower-camel-case
schema.properties.key.case=lower-camel-case

#######################
# Encoding Object
#######################
# headers property's key must be upper-hyphen-case
encoding.headers.key.case=upper-hyphen-case

#######################
# Header Object
#######################
# description property, required
header.description.required=true

#######################
# Components Object
#######################
# schemas property's key must be upper-camel-case
components.schemas.key.case=upper-camel-case
# responses property's key must be upper-camel-case
components.responses.key.case=upper-camel-case
# parameters property's key must be upper-camel-case
components.parameters.key.case=upper-camel-case
# examples property's key must be upper-camel-case
components.examples.key.case=upper-camel-case
# requestBodies property's key must be upper-camel-case
components.requestBodies.key.case=upper-camel-case
# headers property's key must be upper-hyphen-case
components.headers.key.case=upper-hyphen-case
# links property's key must be upper-camel-case
components.links.key.case=upper-hyphen-case
# callbacks property's key must be upper-camel-case
components.callbacks.key.case=upper-camel-case
# headers property's key must be upper-camel-case
components.headers.key.case=upper-camel-case

Compatibility checking

Check whether new OAS spec compatibile with old spec.

Notice: OAS could use Reference Object, two OAS which are different in text maybe semantically same. For example, below old OAS doesn't use Reference Object while the new one uses:

Old OAS

openapi: "3.0.0"
info:
  version: 1.0.0
  title: Swagger Petstore
  license:
    name: MIT
servers:
  - url: http://petstore.swagger.io/v1
paths:
  /pets:
    post:
      summary: List all pets
      operationId: listPets
      requestBody:
        content:
          application/json:
            schema:
              type: array
              items:
                type: object
                properties:
                  Foo:
                    type: string
      responses:
        '200':
          description: A paged array of pets

New OAS

paths:
  /pets:
    post:
      operationId: listPets
      requestBody:
        content:
          application/json: 
            schema:
              $ref: '#/components/schemas/Foo'
      responses:
        '200':
          description: A paged array of pets
components:
  schemas:
    Foo:
      type: array
      items:
        type: object
        properties:
          Foo:
            type: string

So, when do compatibility check we resolve Reference Object in old and new OAS first, then do the check, below is the code snippet using swagger-parser:

OpenAPIV3Parser parser = new OpenAPIV3Parser();

ParseOptions parseOptions = new ParseOptions();
parseOptions.setResolve(true);
parseOptions.setResolveCombinators(true);
parseOptions.setResolveFully(true);
parseOptions.setFlatten(false);

SwaggerParseResult parseResult = parser.readContents(content, null, parseOptions);

So if compatibility violations be found, the reported location will be different from the location in origin OAS spec.

Paths Object doc

• New OAS must include all the path appears in 旧OAS. If path uses Path Templating, even the variable name changed, will be considered semantically different. For example /pets/{foo} and /pets/{bar} are different.
  • See Path Item Object compatibility check rules

Path Item Object doc

• New OAS must inclued all old OAS get/put/post/delete/...Operation Object

Operation Object doc

• operationId property, new and old must be identical
• parameters property, check work must also consider Path Item Object parameters property:
  • New OAS could add new Parameter Object, but the new Parameter Object required property must be false
  • New OAS could deleteParameter Object
  • The check on Parameter Object see Parameter Object compatibility check rules(Under the same Operation Object Parameter Object is identified by name and in property)。
• requestBody property, see Request Body Object compatibility check rules
• responses property, seeResponses Object compatibility check rules

Parameter Object doc

• required property, only allow true(old) -> false(new) change
• allowEmptyValue property, only allow false(old) -> true(new) change
• style property, new and old must be identical
• explode property, new and old must be identical
• allowReserved property, only allow false(old) -> true(new) change
• schema property, see Schema Object compatibility check rules
• contentproperty, new OAS must include all old OAS media type (content keys), and add new media type is not allowed
  • see Media Type Object compatibility check rules

Request Body Object doc

• contentproperty, new OAS must include all old OAS media type (content keys)
  • See Media Type Object compatibility check rules
• required property, only allow true(old) -> false(new) change

Media Type Object doc

• schema property, see Schema Object compatibility check rules
• encoding property, this property only apply to requestBody, so new OAS and old OAS property name(encoding key) must be identical
  • See Encoding Object compatibility check rules

Responses Object doc

• default property, if old OAS doesn't define default, then new OAS should not define default too.
• {Http Status Code} property, new OAS is not allowed to add one.
• See Response Object compatibility check rules

Response Object doc

• headers property, new OAS must include all old OAS header name(headers keys), and add new header name is allowed
  • Header Object see Header Object compatibility check rules
• content property, new OAS must include all old OAS media type(content keys), and add new media type is allowed
  • Media Type Object see Media Type Object compatibility check rules

Schema Object doc

OAS allows Schema Object be directly or indirectly in:

• Request: Parameter Object, Request Body Object, Header Object
• Response: Header Object, Response Object

In different context compatibility check rules are different.

In request context

When Schema Object is in response context, only allow change from more specific form to less specific form.

• type, format combination allowed change:

• allOf, oneOf, anyOf property, combine them first then do check
• multipleOf property, if old OAS is null, then new OAS must == old OAS or new OAS is a factor of old OAS, eg, 6(old)->3(new)
• maximum, maxLength, maxItems, maxProperties, if old OAS is null, then new OAS must be null too. Otherwise, new OAS must be >= old OAS
• minimum, minLenght, minItems, minProperties, if old OAS is null, then new OAS must be null too. Otherwise, new OAS must be <= old OAS.
• exclusiveMaximum, exclusiveMinimum property, only allow change true(old)->false(new)
• uniqueItems property, only allow change true(old)->false(new)
• required property, new OAS must == old OAS or new OAS is old OAS subset
• enum property, new OAS must == old OAS or new OAS is old OAS superset
• properties property, new OAS could add or delete property name(properties key)
• nullable property, only allow change false(old)->true(new)
• discriminator property, new and old must be identical
• xml property, new and old must be identical
• readOnly, writeOnly property, new and old must be identical

In response context

When Schema Object is in response context, only allow change from less specific form to more specific form.

• type, format combination allowed change:

• allOf, oneOf, anyOf property, combine them first then do check
• multipleOf property if old OAS is null. new OAS must == old OAS or new OAS must be a multiple of old OAS, eg, 3(old)->6(new)
• maximum, maxLength, maxItems, maxProperties, if old OAS is null, then new OAS must be null too. Otherwise, new OAS must <= old OAS
• minimum, minLenght, minItems, minProperties, if old OAS is null, then new OAS must be null too. Otherwise, new OAS must >= old OAS
• exclusiveMaximum, exclusiveMinimum property, only allow change false(old)->true(new)
• uniqueItems property, only allow change false(old)->true(new)
• required new OAS must == old OAS or new OAS is old OAS superset
• enum property, new OAS must == old OAS or new OAS is old OAS subset
• properties property, new OAS could add or delete property name(properties key)
• nullable property , only allow change true(old)->false(new)
• discriminator property, new and old must be identical
• xml property, new and old must be identical
• readOnly, writeOnly property, new and old must be identical

Encoding Object doc

Notice: Encoding Object only apply to Request Body Object

• contentType property, new and old must be identical
• headers property, new OAS can not add new he header name (headers key), but and delete header name
  • Header Object see Header Object compatibility check rules
• style property, new and old must be identical
• explode property, new and old must be identical
• allowReserved property, only allow change false(old) -> true(new)

Header Object doc

• schema property, see Schema Object compatibility check rules

Components Object doc

Components Object defines reusable OAS Object, but when doing compatibility check all $ref are resolved, so no need to check Components Object compatibility.