Swagger Generator

This generator is based on Swagger 2.0 specification and it is the most popular specification format for Restful API these days. Although it might be replaced soon with OpenAPI 3.0, this is still the main style in light-rest-4j framework. A lot of our customers are using it to build their restful APIs. In light-rest-4j, we use the specification to scaffold the project and we also use the specification during runtime for OAuth 2.0 scope verification and validation against Swagger for Path Parameters, Query Parameters, Headers and Request Body if exists.

Input

Model

In light-rest-4j framework generator, the model that drives code generation is the Swagger 2.0 specification. When editing it, normally it will be in yaml format with separate files for readability and flexibility. Before leveraging it in light-rest-4j framework, all yaml files need to be bundled and converted into json format in order to be consumed by the framework and generator. Also, a validation needs to be done to make sure that the generated swagger.json is valid against json schema of Swagger 2.0 specification.

Note: currently, we support Swagger 2.0 specification and OpenAPI 3.0 specification. You can find a similar tutorial for OpenAPI 3.0 generator

• Swagger Editor

• Swagger CLI

Config

Here is an exmaple of config.json for swagger generator.

{
  "name": "petstore",
  "version": "1.0.1",
  "groupId": "com.networknt",
  "artifactId": "petstore",
  "rootPackage": "com.networknt.petstore",
  "handlerPackage":"com.networknt.petstore.handler",
  "modelPackage":"com.networknt.petstore.model",
  "overwriteHandler": true,
  "overwriteHandlerTest": true,
  "overwriteModel": true,
  "httpPort": 8080,
  "enableHttp": true,
  "httpsPort": 8443,
  "enableHttps": false,
  "enableRegistry": false,
  "enableParamDescription": true,
  "supportDb": true,
  "dbInfo": {
    "name": "mysql",
    "driverClassName": "com.mysql.jdbc.Driver",
    "jdbcUrl": "jdbc:mysql://mysqldb:3306/oauth2?useSSL=false",
    "username": "root",
    "password": "my-secret-pw"
  },
  "supportH2ForTest": false,
  "supportClient": false
}

In most cases, developers will only update handlers, handler tests and models in a project. Of course, you might need different database for your project and we have a database tutorial that can help you to further config Oracle and Postgres.

Given we have most of our model and config files in model-config repo, most generator input would be from the rest folder in model-config for light-rest-4j framework.

Let’s clone the project to your workspace as we will need it in the following steps. I am using ~/networknt as workspace but it can be anywhere in your home directory.

cd ~/networknt
git clone [email protected]:networknt/model-config.git

Usage

Java Command line

You can download or build the codegen-cli command line jar.

Given we have test swagger.json and config.json in light-rest-4j/src/test/resources folder, the following command line will generate a RESTful petstore API at /tmp/swagger-petstore folder.

Working directory: light-codegen

cd ~/networknt/light-codegen
java -jar codegen-cli/target/codegen-cli.jar -f swagger -o /tmp/swagger-petstore -m light-rest-4j/src/test/resources/swagger.json -c light-rest-4j/src/test/resources/config.json

After you run the above command, you can build and start the service:

cd /tmp/swagger-petstore
mvn clean install exec:exec

To test the service from another terminal:

curl http://localhost:8080/v2/pet/111

The above example use local swagger specification and config file. Let’s try to use files from github.com:

Working directory: light-codegen

rm -rf /tmp/swagger-petstore
cd ~/networknt/light-codegen
java -jar codegen-cli/target/codegen-cli.jar -f swagger -o /tmp/swagger-petstore -m https://raw.githubusercontent.com/networknt/model-config/master/rest/swagger/petstore/2.0.0/swagger.json -c https://raw.githubusercontent.com/networknt/model-config/master/rest/swagger/petstore/2.0.0/config.json

Please note that you need to use a raw url when accessing github files. The above command line will generate a petstore service in /tmp/swagger-petstore.

Here is the example to generate petstore. Assuming model-config is in the same workspace as light-codegen.

Working directory: light-codegen

rm -rf /tmp/swagger-petstore
cd ~/networknt
java -jar light-codegen/codegen-cli/target/codegen-cli.jar -f swagger -o /tmp/swagger-petstore -m model-config/rest/swagger/petstore/2.0.0/swagger.json -c model-config/rest/swagger/petstore/2.0.0/config.json

Docker Command Line

Above local build and command line utility works but it is very hard to use that in devops script. In order to make scripting easier, we have dockerized the command line utility.

The following command is using docker image to generate the code into /tmp/light-codegen/generated:

docker run -it -v ~/networknt/light-codegen/light-rest-4j/src/test/resources:/light-api/input -v /tmp/light-codegen:/light-api/out networknt/light-codegen -f swagger -m /light-api/input/swagger.json -c /light-api/input/config.json -o /light-api/out/generated

On Linux environment, the generated code might belong to root:root and you need to change the owner to yourself before building it.

cd /tmp/light-codegen
sudo chown -R steve:steve generated
cd generated
mvn clean install exec:exec

To test it.

curl localhost:8080/v2/pet/111

Output

Below is the folder structure after generate.

.  
├── app-name
│   ├── LICENSE
│   ├── README.md
│   ├── build.sh
│   ├── dependency-reduced-pom.xml
│   ├── docker
│   │   ├── Dockerfile
│   │   └── Dockerfile-Redhat
│   ├── pom.xml
│   ├── app-name.iml
│   └── src
│       ├── main
│       │   ├── java
│       │   │   └── com
│       │   │       └── networknt
│       │   │           └── app-name
│       │   │               ├── handler
│       │   │               │   ├── ItemDeleteHandler.java
│       │   │               │   ├── ItemGetHandler.java
│       │   │               │   ├── ItemPutHandler.java
│       │   │               │   └── ItemPostHandler.java
│       │   │               └── model
│       │   │                   └── Model.java
│       │   └── resources
│       │       ├── config
│       │       │   ├── handler.yml
│       │       │   ├── mask.yml
│       │       │   ├── openapi-security.yml
│       │       │   ├── openapi-validator.yml
│       │       │   ├── openapi.yaml
│       │       │   ├── primary.crt
│       │       │   ├── secondary.crt
│       │       │   ├── secret.yml
│       │       │   ├── server.keystore
│       │       │   ├── server.truststore
│       │       │   ├── server.yml
│       │       │   └── service.yml
│       │       ├── logback.xml
│       │       └── todos.properties
│       └── test
│           ├── java
│           │   └── com
│           │       └── networknt
│           │           └── app-name
│           │               └── handler
│           └── resources
│               ├── config
│               │   ├── client.keystore
│               │   ├── client.truststore
│               │   ├── client.yml
│               │   └── server.yml
│               └── logback-test.xml
└── app-name.iml

Reference of Generated Configs

handler.yml
mask.yml
openapi-security.yml
openapi-validator.yml
openapi.yaml
primary.crt
secondary.crt
secret.yml
server.keystore
server.truststore
server.yml
service.yml

Docker Scripting

You can use docker run command to call the generator but it is very complicated for the parameters. In order to make things easier and friendlier to devops flow. Let’s create a script to call the command line from docker image.

If you look at the docker run command you can see that we basically need one input folder for schema and config files and one output folder to generated code. Once these volumes are mapped to local directory and with framework specified, it is easy to derive other files based on convention.

cd ~/networknt/model-config
./generate.sh swagger ~/networknt/model-config/rest/swagger/petstore/2.0.0 /tmp/petstore

Now you should have a project generated in /tmp/petstore/genereted

Codegen Site

You can generate a single project or multiple projects from the site https://codegen.lightapi.net with your model and config files.