CORS Middleware for Gin-Gonic Framework

gin-middleware-cors is a middleware written in Go (Golang) specifically for the Gin Framework that implements the Cross Origin Resource Sharing specification from the W3C. Implementing CORS headers enable pages within a modern web browser to consume resources (such as REST APIs) from servers that are on a different domain.

Getting Started

To use this library, add the following code into your Gin router setup:

import "github.com/benpate/go-cors"

// Initialize a new Gin router	
router := gin.New()

// Apply the middleware to the router (works with groups too)
router.Use(cors.Middleware(cors.Config{
	Origins:     "*",
	Headers:     "Origin, Authorization, Content-Type",
	Methods:     "GET, PUT, POST, DELETE",
	Credentials: true,
}))

Setup Options

The middleware can be configured with four options, which match the HTTP headers that it generates:

Parameter	Type	Details
Origins	string	A comma+space separated list of allowable origins that is passed to the browser in the Access-Control-Allow-Origins header. For example: "http://localhost, http://api.server.com, http://files.server.com"
Headers	string	A comma+space separated list of allowable HTTP header codes that is passed to the browser in the Access-Control-Allow-Headers header. Currently defaults to "Cache-Control, Pragma, Origin, Authorization, Content-Type"
Methods	string	A comma+space separated list of allowable HTTP methods that is passed to the browser in the Access-Control-Allow-Methods header. Currently defaults to "GET, POST, PUT, DELETE"
Credentials	bool	A boolean value (true or false) that is passed in the Access-Control-Allow-Credentials header. If true, then cookies and Authorization headers are allowed in requests to this resource. Defaults to false.

Caveats

I'm a new golang developer, and welcome your feedback about creating idiomatic Go middleware. This code is highly experimental for me. While I'm expecting to use it in large-scale web applications, it is almost certain to undergo massive changes to the API before that happens.

CORS Resources

• HTML Rocks Tutorial: Using CORS
• Mozilla Developer Network: CORS Reference
• CORS Specification from W3C

License

This code is licensed for free under the Apache 2.0 License. Copyright © 2015 Ben & Fil LLC