OpenAPI Generator

A Go implementation of the OpenAPI Generator inspired by the original Java-based project.

Why

I ran into issues with Java dependencies and performance in large projects, and many issues stay unresolved in the repository for a long time. I want to build something simpler, easier to maintain, and portable as a single binary with minimal dependencies.

Features

• Single binary for easy installation and use
• Fast generation times without JVM overhead
• Load specs from local files or remote URLs
• Command-line interface compatible with the original OpenAPI Generator
• Supports OpenAPI 3.x and Swagger 2.0 specifications (auto-converts 2.0 -> 3.x)

Installation

Standalone Binaries

Download pre-built binaries from the releases page:

Linux (amd64/arm64)

# Download the binary (replace with your architecture)
curl -LO https://github.com/xseman/openapi-generator/releases/latest/download/openapi-generator-linux-amd64

# Make it executable
chmod +x openapi-generator-linux-amd64

# Move to your PATH
sudo mv openapi-generator-linux-amd64 /usr/local/bin/openapi-generator

macOS (amd64/arm64)

# Download the binary (amd64 for Intel, arm64 for Apple Silicon)
curl -LO https://github.com/xseman/openapi-generator/releases/latest/download/openapi-generator-darwin-arm64

# Make it executable
chmod +x openapi-generator-darwin-arm64

# Move to your PATH
sudo mv openapi-generator-darwin-arm64 /usr/local/bin/openapi-generator

Windows (amd64)

# Download from: https://github.com/xseman/openapi-generator/releases/latest/download/openapi-generator-windows-amd64.exe
# Add the .exe to your PATH

Package Managers

Debian/Ubuntu

# Download and install (replace version and architecture as needed)
curl -LO https://github.com/xseman/openapi-generator/releases/latest/download/openapi-generator_0.1.0_amd64.deb
sudo dpkg -i openapi-generator_0.1.0_amd64.deb

RHEL/Fedora/CentOS

# Download and install (replace version and architecture as needed)
curl -LO https://github.com/xseman/openapi-generator/releases/latest/download/openapi-generator-0.1.0-1.x86_64.rpm
sudo rpm -i openapi-generator-0.1.0-1.x86_64.rpm

From Source

go install github.com/xseman/openapi-generator/cmd/openapi-generator@latest

Templates

Client

• typescript-fetch

Server

• (Coming soon)

Usage

openapi-generator generate \
    -i openapi.yaml \
    -g <template> \
    -o ./generated \
    -p key=value \
    -c config.yaml \
    --verbose

CLI Options

Option	Short	Description
--input-spec	-i	Location of the OpenAPI spec (file or URL)
--generator-name	-g	Generator to use (currently: typescript-fetch)
--output	-o	Output directory
--config	-c	Configuration file (JSON/YAML)
--template-dir	-t	Custom template directory
--additional-properties	-p	Key=value pairs for generator options
--skip-validate-spec		Skip OpenAPI spec validation
--verbose	-v	Enable verbose output

Note: For generator-specific options, see the template documentation (e.g., typescript-fetch options).

Development

Building and Testing

# Build the binary
make build

# Run tests
make test

# Run tests with coverage
make cover

# Format code
make fmt

# Run linter
make lint

# Run all quality checks
make quality

# Clean build artifacts
make clean

# Show all available targets
make help

Manual Testing

# Generate from a spec
./bin/openapi-generator generate \
    -i petstore.yaml \
    -g typescript-fetch \
    -o ./out

# List available generators
./bin/openapi-generator list

# Show config options for a generator
./bin/openapi-generator config-help typescript-fetch

CI/CD

This project includes a comprehensive CI/CD pipeline:

• Quality Checks: Automated testing, linting (golangci-lint), and builds on every push/PR
• Coverage Reports: Test coverage reports posted as comments on pull requests
• Automated Releases: Release-please based releases with multi-platform binary builds
• Platform Support: Linux (amd64, arm64), macOS (amd64, arm64), Windows (amd64)
• Package Formats: .deb and .rpm packages for Linux distributions

See CI_CD_IMPLEMENTATION.md for detailed documentation.

Architecture

Core Components

Component	Package	Description
Parser	internal/parser	Parses OpenAPI 2.0/3.x specs using kin-openapi
Codegen	internal/codegen	Data structures mirroring Java's CodegenModel
Generator	internal/generator	Generator interface and implementations
Template	internal/template	Mustache template engine with lambdas
Config	internal/config	Configuration structs for generators

Generation Pipeline

%%{init: {'theme': 'neutral' } }%%
sequenceDiagram
    participant CLI
    participant Parser
    participant Config
    participant Codegen
    participant Templates

    CLI->>Parser: Load Spec (YAML/JSON)
    Parser-->>Parser: Convert Swagger 2.0 to OpenAPI 3.x
    Parser-->>CLI: Parsed Spec

    CLI->>Config: Merge CLI + File Config
    Config-->>CLI: Resolved Options

    CLI->>Codegen: Transform to CodegenModels
    Codegen-->>Codegen: Map Types & Properties
    Codegen-->>Codegen: Extract Operations
    Codegen-->>CLI: Codegen Models

    CLI->>Templates: Render API Classes
    Templates-->>CLI: Generated API Files

    CLI->>Templates: Render Models
    Templates-->>CLI: Generated Model Files

    CLI->>Templates: Render Supporting Files
    Templates-->>CLI: Runtime & Configuration Files

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