OpenAPITools 实践

OpenAPITools 可以依据 REST API 描述文件，自动生成服务端桩（Stub）代码、客户端 SDK 代码，及文档等。其是社区版的 Swagger ，差异可见：OpenAPI Generator vs Swagger Codegen。

本文将从零开始设计和编写 API 文件，并生成 Go Gin 服务端代码，与 Python SDK 代码。更多语言或框架，也是一样操作的。

快速开始

先熟悉下工具，直接用官方 Docker 镜像生成 Petstore 样例的 Go SDK 代码：

docker run --rm -v "${PWD}:/local" openapitools/openapi-generator-cli generate \
-i https://raw.githubusercontent.com/openapitools/openapi-generator/master/modules/openapi-generator/src/test/resources/3_0/petstore.yaml \
-g go \
-o /local/out/go

生成代码在当前目录的 ./out/go 。

打开 Swagger Editor File > Import URL 查看 petstore.yaml API：

查看 openapi-generator-cli 用法:

docker run --rm -it \
-v "${PWD}:/local" \
--entrypoint /bin/bash \
openapitools/openapi-generator-cli

ln -s /usr/local/bin/docker-entrypoint.sh /usr/local/bin/openapi-generator
openapi-generator help
openapi-generator help generate

动手实践

设计 RESTful API

打开 Swagger Editor 设计 API：

• /albums

  • GET - Get all albums
  • POST - Create a new album

• /albums/:id

  • GET - Get an album by its id
  • PUT - Update an album by its id
  • DELETE - Delete an album by its id

完整 API 描述文件见 spec/api.yaml，主要包含三部分：

1 头部： API 信息

openapi: 3.0.0
info:
  title: Start OpenAPITools
  description: Let's practice designing our api.
  version: 0.1.0
  license:
    name: MIT
    url: https://spdx.org/licenses/MIT.html
servers:
  - url: https://github.com/ikuokuo/start-openapitools

2 中间： paths 及其操作 (get, post, etc.)

paths:
  /albums/{id}:
    get:
      tags:
        - album
      summary: Get an album by its id
      operationId: getAlbum
      parameters:
        - $ref: '#/components/parameters/AlbumId'
      responses:
        200:
          description: Get success, return the album
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Album'
        404:
          description: Album not found

3 底部： 可重用的 components，于文档里 $ref 引用

components:
  parameters:
    AlbumId:
      name: id
      in: path
      description: Album id
      required: true
      schema:
        type: string
  schemas:
    Album:
      title: Album
      type: object
      required:
        - title
        - artist
        - price
      properties:
        id:
          type: string
          format: uuid
        title:
          type: string
          maxLength: 200
          minLength: 1
        artist:
          type: string
          maxLength: 100
          minLength: 1
        price:
          type: number
          format: double
          minimum: 0.0
        created_at:
          type: string
          format: date-time
        updated_at:
          type: string
          format: date-time

具体说明，请阅读 OpenAPI Specification。

在线生成代码

可以用线上服务快速生成代码：

• latest stable version: https://api.openapi-generator...

以下则是自己动手生成的过程。

生成 Server Stub 代码

生成 Go Gin 桩（Stub）代码：

docker run --rm -it \
-v "${PWD}:/local" \
--entrypoint /bin/bash \
openapitools/openapi-generator-cli

ln -s /usr/local/bin/docker-entrypoint.sh /usr/local/bin/openapi-generator

# Config Options for go-gin-server
#  https://openapi-generator.tech/docs/generators/go-gin-server
openapi-generator config-help -g go-gin-server

openapi-generator generate \
-g go-gin-server \
-i /local/spec/swagger.yaml \
-o /local/out/gin-server \
--additional-properties=packageName=startapi

生成内容：

❯ tree out/gin-server -aF --dirsfirst
out/gin-server
├── .openapi-generator/
├── api/
│   └── openapi.yaml
├── go/
│   ├── README.md
│   ├── api_album.go
│   ├── api_albums.go
│   ├── model_album.go
│   └── routers.go
├── .openapi-generator-ignore
├── Dockerfile
└── main.go

简单实现 GetAlbum 接口，位于 go/api_album.go：

// GetAlbum - Get an album by its id
func GetAlbum(c *gin.Context) {
    c.JSON(http.StatusOK, Album{
        Id:        "3fa85f64-5717-4562-b3fc-2c963f66afa6",
        Title:     "Start OpenAPITools",
        Artist:    "GoCoding",
        Price:     0.99,
        CreatedAt: time.Now(),
        UpdatedAt: time.Now(),
    })
}

运行服务：

cd out/gin-server/
# 初始化模块
go mod init github.com/ikuokuo/start-openapitools/gin-server
go mod tidy

# 修改 `main.go` 中的 import 路径
#  sw "github.com/ikuokuo/start-openapitools/gin-server/go"
# 替换成本地路径
go mod edit -replace github.com/ikuokuo/start-openapitools/gin-server/go=./go

运行结果：

❯ go run .
2021/11/05 18:20:00 Server started
[GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.

[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
 - using env:   export GIN_MODE=release
 - using code:  gin.SetMode(gin.ReleaseMode)

[GIN-debug] GET    /ikuokuo/start-openapitools/ --> github.com/ikuokuo/start-openapitools/gin-server/go.Index (3 handlers)
[GIN-debug] DELETE /ikuokuo/start-openapitools/albums/:id --> github.com/ikuokuo/start-openapitools/gin-server/go.DeleteAlbum (3 handlers)
[GIN-debug] GET    /ikuokuo/start-openapitools/albums/:id --> github.com/ikuokuo/start-openapitools/gin-server/go.GetAlbum (3 handlers)
[GIN-debug] PUT    /ikuokuo/start-openapitools/albums/:id --> github.com/ikuokuo/start-openapitools/gin-server/go.PutAlbum (3 handlers)
[GIN-debug] GET    /ikuokuo/start-openapitools/albums --> github.com/ikuokuo/start-openapitools/gin-server/go.GetAlbums (3 handlers)
[GIN-debug] POST   /ikuokuo/start-openapitools/albums --> github.com/ikuokuo/start-openapitools/gin-server/go.PostAlbums (3 handlers)
[GIN-debug] Listening and serving HTTP on :8080

❯ curl http://localhost:8080/ikuokuo/start-openapitools/
Hello World!

生成 Client SDK 代码

生成 Python SDK 代码：

docker run --rm -it \
-v "${PWD}:/local" \
--entrypoint /bin/bash \
openapitools/openapi-generator-cli

ln -s /usr/local/bin/docker-entrypoint.sh /usr/local/bin/openapi-generator

# Config Options for python
#  https://openapi-generator.tech/docs/generators/python
openapi-generator config-help -g python

openapi-generator generate \
-g python \
-i /local/spec/swagger.yaml \
-o /local/out/py-sdk \
--additional-properties=packageName=startapi \
--additional-properties=library=urllib3

生成内容：

❯ tree out/py-sdk -aF --dirsfirst
out/py-sdk
├── .openapi-generator/
├── docs/
├── startapi/
│   ├── api/
│   │   ├── __init__.py
│   │   ├── album_api.py
│   │   └── albums_api.py
│   ├── apis/
│   │   └── __init__.py
│   ├── model/
│   │   ├── __init__.py
│   │   └── album.py
│   ├── models/
│   │   └── __init__.py
│   ├── __init__.py
│   ├── api_client.py
│   ├── configuration.py
│   ├── exceptions.py
│   ├── model_utils.py
│   └── rest.py
├── test/
├── .gitignore
├── .gitlab-ci.yml
├── .openapi-generator-ignore
├── .travis.yml
├── README.md
├── git_push.sh
├── requirements.txt
├── setup.cfg
├── setup.py
├── test-requirements.txt
└── tox.ini

测试 SDK 使用，调用此前实现的 GetAlbum 接口：

❯ cd out/py-sdk/
❯ python - <<EOF
from startapi import ApiClient, Configuration, apis

config = Configuration(host="http://localhost:8080/ikuokuo/start-openapitools")
with ApiClient(configuration=config) as client:
  api = apis.AlbumApi(client)
  album = api.get_album("xxxxx")
  print(album)
EOF
{'artist': 'GoCoding',
 'created_at': datetime.datetime(2021, 11, 5, 18, 30, 0, 545305, tzinfo=tzoffset(None, 28800)),
 'id': '3fa85f64-5717-4562-b3fc-2c963f66afa6',
 'price': 0.99,
 'title': 'Start OpenAPITools',
 'updated_at': datetime.datetime(2021, 11, 5, 18, 30, 0, 545305, tzinfo=tzoffset(None, 28800))}

最后

实践下来，感觉不错。很多场合，生成 SDK 就够用了。另外，生成自动化测试代码，也值得一试。

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