Gradle Swagger Generator Plugin

Table of content

• Introduction
• Code Generation
• Document Generation
  • Swagger UI
  • ReDoc
  • HTML
• Recipes
  • Use configuration file
  • Build generated code
  • Validate YAML before code generation
  • Selective generation
  • Use custom template
  • Use custom generator class
  • Externalize template or generator class
  • Use multiple sources
  • Switch version of Swagger Codegen
  • Configure Swagger UI
• Compatibility
  • Swagger Codegen v3 and Java 16+
• Settings
  • Task type ValidateSwagger
  • Task type GenerateSwaggerCode
  • Task type GenerateSwaggerUI
  • Task type GenerateReDoc
• Contributions

Introduction

This is a Gradle plugin for the following tasks:

• Validate an OpenAPI YAML.
• Generate source from an OpenAPI YAML using Swagger Codegen v2/v3 and OpenAPI Generator v3.
• Generate Swagger UI with an OpenAPI YAML.
• Generate ReDoc with an OpenAPI YAML.

See also the following examples:

• Swagger UI example (generated by ui-v3/basic project)
• ReDoc example (generated by redoc/basic project)
• HTML document example (generated by codegen-v2/html project)
• HTML document example (generated by codegen-v3/html project)
• HTML document example (generated by openapi-v3/html project)

Code Generation

Create a project with the following build script.

plugins {
  id 'org.hidetake.swagger.generator' version '2.19.2'
}

repositories {
  mavenCentral()
}

dependencies {
  swaggerCodegen 'io.swagger:swagger-codegen-cli:2.4.34'             // Swagger Codegen V2
  swaggerCodegen 'io.swagger.codegen.v3:swagger-codegen-cli:3.0.47'  // or Swagger Codegen V3
  swaggerCodegen 'org.openapitools:openapi-generator-cli:3.3.4'     // or OpenAPI Generator
}

swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
    code {
      language = 'spring'
    }
  }
}

The task generates source code into build/swagger-code-petstore.

% ./gradlew generateSwaggerCode
:resolveSwaggerTemplate NO-SOURCE
:generateSwaggerCodePetstore
:generateSwaggerCode NO-SOURCE

Document Generation

Swagger UI

Create a project with the following build script.

plugins {
  id 'org.hidetake.swagger.generator' version '2.19.2'
}

repositories {
  mavenCentral()
}

dependencies {
  swaggerUI 'org.webjars:swagger-ui:3.52.5'
}

swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
  }
}

The task generates an API document as build/swagger-ui-petstore.

% ./gradlew generateSwaggerUI
:generateSwaggerUIPetstore
:generateSwaggerUI NO-SOURCE

ReDoc

Create a project with the following build script.

plugins {
  id 'org.hidetake.swagger.generator' version '2.19.2'
}

swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
  }
}

The task generates an API document as build/redoc-petstore.

% ./gradlew generateReDoc
:generateReDocPetstore
:generateReDoc NO-SOURCE

HTML

Create a project with the following build script.

plugins {
  id 'org.hidetake.swagger.generator' version '2.19.2'
}

repositories {
  mavenCentral()
}

dependencies {
  swaggerCodegen 'io.swagger:swagger-codegen-cli:2.4.34'             // Swagger Codegen V2
  swaggerCodegen 'io.swagger.codegen.v3:swagger-codegen-cli:3.0.47'  // or Swagger Codegen V3
}

swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
    code {
      language = 'html'  // html or html2
    }
  }
}

The task generates a static HTML into build/swagger-code-petstore.

% ./gradlew generateSwaggerCode
:resolveSwaggerTemplate NO-SOURCE
:generateSwaggerCodePetstore
:generateSwaggerCode NO-SOURCE

Recipes

See the example projects in acceptance-test.

Use configuration file

We can use a JSON configuration file as follows:

swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
    code {
      language = 'spring'
      configFile = file('config.json')
    }
  }
}

config.json depends on the language and framework. For example,

{
  "library": "spring-mvc",
  "modelPackage": "example.model",
  "apiPackage": "example.api",
  "invokerPackage": "example"
}

Run the task with Help postfix to show available JSON configuration.

% ./gradlew generateSwaggerCodePetstoreHelp
:generateSwaggerCodePetstoreHelp
=== Available raw options
NAME
        swagger-codegen-cli generate - Generate code with chosen lang

SYNOPSIS
        swagger-codegen-cli generate
                [(-a <authorization> | --auth <authorization>)]
...

=== Available JSON configuration for language spring:

CONFIG OPTIONS
	sortParamsByRequiredFlag
...

Build generated code

It is recommended to generate code into an ephemeral directory (e.g. build) and exclude it from a Git repository. We can compile generated code as follows:

swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
    code {
      language = 'spring'
      configFile = file('config.json')
    }
  }
}

// Configure compile task dependency and source
compileJava.dependsOn swaggerSources.petstore.code
sourceSets.main.java.srcDir "${swaggerSources.petstore.code.outputDir}/src/main/java"
sourceSets.main.resources.srcDir "${swaggerSources.petstore.code.outputDir}/src/main/resources"

See also the following examples:

• codegen-v2/java-spring
• codegen-v3/java-spring
• openapi-v3/java-spring

Validate YAML before code generation

It is recommended to validate an OpenAPI YAML before code generation in order to avoid invalid code generated.

If you use OpenAPI Generator as generator, YAML validation is embeding.

We can validate a YAML as follows:

swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
    code {
      language = 'spring'
      configFile = file('config.json')
      // Validate YAML before code generation. for Swagger Codegen V2 / V3
      dependsOn validation
    }
  }
}

Selective generation

We can control output of code generation. At default everything is generated but only models and APIs are generated in the following:

swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
    code {
      language = 'spring'
      configFile = file('config.json')
      // Generate only models and controllers
      components = ['models', 'apis']
    }
  }
}

components property accepts a list of strings or map.

// generates only models
components = ['models']
components = [models: true]

// generate only User and Pet models
components = [models: ['User', 'Pet']]
components = [models: 'User,Pet']

// generate only APIs (without tests)
components = [apis: true, apiTests: false]
components = [apis: true, apiTests: null]

See selective generation section for details.

Use custom template

We can use a custom template for the code generation as follows:

// build.gradle
swaggerSources {
  inputFile = file('petstore.yaml')
  petstore {
    language = 'spring'
    // Path to the template directory
    templateDir = file('templates/spring-mvc')
  }
}

See also the following examples:

• codegen-v2/custom-template
• codegen-v3/custom-template
• openapi-v3/custom-template

Use custom generator class

We can use a custom generator class for the code generation as follows:

// build.gradle
swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
    code {
      // FQCN of the custom generator class
      language = 'CustomGenerator'
    }
  }
}

dependencies {
  swaggerCodegen project('generators')
}

swaggerSources*.code*.dependsOn 'generators:jar'

// generators/build.gradle (child project)
dependencies {
  implementation 'io.swagger:swagger-codegen-cli:2.4.24'
}

// generators/src/main/groovy/CustomGenerator.groovy
import io.swagger.codegen.languages.SpringCodegen

class CustomGenerator extends SpringCodegen {
}

See also the following examples:

• codegen-v2/custom-class
• codegen-v3/custom-class
• openapi-v3/custom-class

Externalize template or generator class

In some large use case, we can release a template or generator to an external repository and use them from projects.

// build.gradle
repositories {
  // Use external repository for the template and the generator class
  maven {
    url 'https://example.com/nexus-or-artifactory'
  }
  mavenCentral()
}

dependencies {
  swaggerCodegen 'io.swagger:swagger-codegen-cli:2.4.34'
  // Add dependency for the template
  swaggerTemplate 'com.example:swagger-templates:1.0.0'
  // Add dependency for the generator class
  swaggerCodegen 'com.example:swagger-generators:1.0.0'
}

swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
    code {
      language = 'spring'
      // The plugin automatically extracts template JAR into below destination
      templateDir = file("${resolveSwaggerTemplate.destinationDir}/spring-mvc")
    }
  }
}

See also the following examples:

• codegen-v2/externalize-template and codegen-v2/externalize-class
• codegen-v3/externalize-template and codegen-v3/externalize-class
• openapi-v3/externalize-template and openapi-v3/externalize-class

Use multiple sources

We can handle multiple sources in a project as follows:

// build.gradle
swaggerSources {
    petstoreV1 {
        inputFile = file('v1-petstore.yaml')
        code {
            language = 'spring'
            configFile = file('v1-config.json')
        }
    }
    petstoreV2 {
        inputFile = file('v2-petstore.yaml')
        code {
            language = 'spring'
            configFile = file('v2-config.json')
        }
    }
}

compileJava.dependsOn swaggerSources.petstoreV1.code, swaggerSources.petstoreV2.code
sourceSets.main.java.srcDirs "${swaggerSources.petstoreV1.code.outputDir}/src/main/java", "${swaggerSources.petstoreV2.code.outputDir}/src/main/java"
sourceSets.main.resources.srcDirs "${swaggerSources.petstoreV1.code.outputDir}/src/main/resources", "${swaggerSources.petstoreV2.code.outputDir}/src/main/resources"

See also the following examples:

• codegen-v2/multiple-sources
• codegen-v3/multiple-sources
• openapi-v3/multiple-sources

Switch version of Swagger Codegen

We can use multiple versions of Swagger Codegen as follows:

// build.gradle
configurations {
    swaggerCodegenV2
    swaggerCodegenV3
}

dependencies {
    swaggerCodegenV2 'io.swagger:swagger-codegen-cli:2.4.24'
    swaggerCodegenV3 'io.swagger.codegen.v3:swagger-codegen-cli:3.0.30'
}

swaggerSources {
    petstoreV2 {
        inputFile = file('v2-petstore.yaml')
        code {
            language = 'spring'
            configuration = configurations.swaggerCodegenV2
        }
    }
    petstoreV3 {
        inputFile = file('v3-petstore.yaml')
        code {
            language = 'spring'
            configuration = configurations.swaggerCodegenV3
        }
    }
}

See also the following examples:

• codegen-v3/multiple-codegen-versions
• openapi-v3/multiple-codegen-versions

Configure Swagger UI

We can configure Swagger UI by overwriting the default index.html as follows:

swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
    ui {
      doLast {
        copy {
          from 'index.html'
          into outputDir
        }
      }
    }
  }
}

You can create an index.html from the Swagger UI official one. It must satisfy the followings:

• Put <script src="./swagger-spec.js"> in order to load a Swagger spec. The plugin exports the Swagger spec as swagger-spec.js file while generation.
• Set spec: window.swaggerSpec in SwaggerUIBundle() parameters.
• Set validatorUrl: null in SwaggerUIBundle() parameters in order to turn off the validator badge.

See also the following examples:

• ui-v3/basic
• ui-v2/basic (if you need Swagger UI 2.x)

Compatibility

Swagger Codegen v3 and Java 16+

To use Swagger Codegen v3 on Java 16 or later, you need to set jvmArgs as follows:

swaggerSources {
  petstore {
    inputFile = file('petstore.yaml')
    code {
      language = 'html'
      jvmArgs = ['--add-opens=java.base/java.util=ALL-UNNAMED'] // for Swagger Codegen v3 on Java 16+
    }
  }
}

See #221 for details.

Settings

The plugin adds validateSwagger, generateSwaggerCode, generateSwaggerUI and GenerateReDoc tasks. A task will be skipped if no input file is given.

Task type ValidateSwagger

The task accepts below properties.

Key	Type	Value	Default value
inputFile	File	Swagger spec file.	Mandatory
reportFile	File	File to write validation report.	$buildDir/tmp/validateSwagger/report.yaml

It depends on the following JSON schema:

• OpenAPI Specification version 2.0

Task type GenerateSwaggerCode

The task accepts below properties.

Key	Type	Value	Default value
language	String	Language to generate.	Mandatory
inputFile	File	Swagger spec file.	Mandatory
outputDir	File	Directory to write generated files.	$buildDir/swagger-code
wipeOutputDir	Boolean	Wipe the outputDir before generation.	true
library	String	Library type.	None
configFile	File	JSON configuration file.	None
templateDir	File	Directory containing the template.	None
components	List or Map	Components to generate that is a list of models, apis and supportingFiles.	All components
additionalProperties	Map of String, String	Additional properties.	None
rawOptions	List of Strings	Raw command line options for Swagger Codegen	None
configuration	String or Configuration	Configuration for Swagger Codegen	configurations.swaggerCodegen
jvmArgs	List of Strings	Arguments passed to jvm	None

Task type GenerateSwaggerUI

The task accepts below properties.

Key	Type	Value	Default value
inputFile	File	Swagger spec file.	Mandatory
outputDir	File	Directory to write Swagger UI files.	$buildDir/swagger-ui
wipeOutputDir	Boolean	Wipe the outputDir before generation.	true

Note that options and header are no longer supported since 2.10.0. See the Migration Guide for details.

Task type GenerateReDoc

The task accepts below properties.

Key	Type	Value	Default value
inputFile	File	Swagger spec file.	Mandatory
outputDir	File	Directory to write ReDoc files.	$buildDir/swagger-redoc
wipeOutputDir	Boolean	Wipe the outputDir before generation.	true
scriptSrc	String	URL to ReDoc JavaScript.	//rebilly.github.io/ReDoc/releases/latest/redoc.min.js
title	String	HTML title.	ReDoc - $filename
options	Map of Strings	ReDoc tag attributes.	Empty map

Contributions

This is an open source software licensed under the Apache License Version 2.0. Feel free to open issues or pull requests.

CI requires the following variables.

Environment Variable	Purpose
$GRADLE_PUBLISH_KEY	Publish the plugin to Gradle Plugins
$GRADLE_PUBLISH_SECRET	Publish the plugin to Gradle Plugins