goas - Go + OAS (OpenAPI Specification)

Pure OpenAPI 3.2 generator for Go.

Parses Go code comments to generate OpenAPI 3.2 specification JSON.

Features

• Global Annotations: Configure Info, Servers, Tags, Security in main.go.
• API Annotations: Define Router, Params, Request Body, Responses in handler functions.
• Type Resolution: Automatically converts Go structs to OpenAPI Schemas.
• Generics Support: Full support for Go 1.18+ generic types (e.g., Response[User]).
• Standard Library Parsing: Supports standard library types like time.Time, os.File.

Status

Current Version: 0.1.0 (Development)

• Global Annotation Parsing
• API Operation Parsing
• Schema Generation (Generics support included)
• CLI Tool

Installation

Method 1: Global Installation (CLI)

Install the command-line tool globally:

go install github.com/promonkeyli/goas/cmd/goas@latest

Method 2: Project Dependency (Library)

Add as a dependency to your project:

go get github.com/promonkeyli/goas

Usage

1. CLI Usage

If installed globally, run directly:

goas -dir ./cmd,./internal -output ./api

Or run via go run in your project:

go run github.com/promonkeyli/goas/cmd/goas -dir ./cmd,./internal -output ./api

2. Library Usage (Function Call)

You can also integrate goas directly into your Go code (e.g., in a generator script):

package main

import (
    "log"
    "github.com/promonkeyli/goas/pkg/goas"
)

func main() {
    config := goas.Config{
        Dirs:   []string{"./cmd", "./internal"},
        Output: "./api",
    }

    if err := goas.Run(config); err != nil {
        log.Fatalf("Failed to generate OpenAPI: %v", err)
    }
}

Quick Start

1. Global Configuration (main.go)

package main

// @OpenAPI 3.2.0
// @Title Pet Store API
// @Version 1.0.0
// @Description Supports user management and file uploads.
// @Server http://localhost:8080/v1 name=dev Development
// @SecurityScheme ApiKeyAuth apiKey header X-API-KEY
func main() {
    // ...
}

2. Implementation (handler.go)

package handler

// Response Generic Response
type Response[T any] struct {
    Code    int    `json:"code"`
    Message string `json:"message"`
    Data    T      `json:"data"`
}

// User Model
type User struct {
    ID   int    `json:"id" desc:"User ID"`
    Name string `json:"name" desc:"Username"`
}

// GetUser Get User Info
// @Summary Get User Info
// @Tags user
// @Param id path int true "User ID"
// @Success 200 {object} Response[User] "Success"
// @Router /users/{id} [get]
func GetUser() {
    // ...
}

Flags

• -dir: Comma-separated list of directories to scan (recursive).
• -output: Output directory for openapi.json.

Documentation

• GOAS Annotation Specification: Detailed guide on using goas annotations.
• OpenAPI 3.2.0 Field Reference: Quick reference for OpenAPI 3.2.0 objects and fields.
• OpenAPI Specification 3.2.0: Full OpenAPI 3.2.0 Specification.