uncors

A simple dev HTTP/HTTPS proxy for replacing CORS headers.

Quick Install

Homebrew (macOS | Linux)

If you are on macOS or Linux and using Homebrew, you can install uncors with the following one-liner:

brew install evg4b/tap/uncors

Scoop (Windows)

If you are on Windows and using Scoop, you can install uncors with the following commands:

scoop bucket add evg4b https://github.com/evg4b/scoop-bucket.git
scoop install evg4b/uncors

Binary (Cross-platform)

Download the appropriate version for your platform from UNCORS releases page. Once downloaded, the binary can be run from anywhere. You don’t need to install it into a global location. This works well for shared hosts and other systems where you don’t have a privileged account.

Ideally, you should install it somewhere in your PATH for easy use. /usr/local/bin is the most probable location.

Docker

We currently offer images for Docker https://hub.docker.com/r/evg4b/uncors

docker run -p 3000:3000 evg4b/uncors --source http://local.github.com --target //github.com

Source

Prerequisite Tools

• Git
• Go (at least Go 1.11)

Fetch from GitHub

UNCORS uses the Go Modules support built into Go 1.11 to build. The easiest way to get started is to clone UNCORS source code in a directory outside the GOPATH, as in the following example:

mkdir $HOME/src
cd $HOME/src
git clone https://github.com/evg4b/uncors.git
cd uncors
go install

If you are a Windows user, substitute the $HOME environment variable above with %USERPROFILE%.

Usage

./uncors --port 8080 --target 'https://github.com' --source 'http://localhost'

Parameters

• --source - Local host with protocol for to the resource from which proxying will take place.
• --target - Target host with protocol for to the resource to be proxy.
• --http-port - Local HTTP listened port.
• --https-port - Local HTTPS listened port.
• --cert-file - Path to HTTPS certificate file.
• --key-file - Path to matching for certificate private key.
• --proxy - HTTP/HTTPS proxy to provide requests to real server (used system by default).
• --mocks - File with defined mocks

Mocks

Uncors has endpoint mocks mechanism. All mocks should be defined in yaml file and passed as parameter --mocks. Currently available path, method, queries and headers filters (for more information see gorilla/mux route matching) .

Mocks file example:

- path: /hello
  response:
    code: 200
    raw-content: '
      Hello word
    '
- path: /word
  method: POST
  queries:
    param1: param 1 value
    param2: param 1 value
  headers:
    header1: header 1 value
    header2: header 2 value
  response:
    code: 200
    headers:
      header1: header 1 value
      header2: header 2 value
    raw-content: '
      { "status": "ok" }
    '

At the moment supported only raw response content. Content should be defined as multiline string (see more here). Content-Type will be set automatically, but you can specify custom content type via headers section.

How it works

sequenceDiagram
    participant Client
    participant Uncors
    participant Server


    alt Handling OPTIONS queries 
        Client ->> Uncors: Access-Control-Request
        Uncors ->> Client: Allow-Control-Request
    end
    
    alt Handling Data queries 
      Client ->> Uncors: GET, POST, PUT... query
      Note over Uncors: Replacing url with target<br/> in headers and cookies
      Uncors-->>Server: Real GET, POST, PUT... query
      Server->>Uncors: Real responce
      Note over Uncors: Replacing url with source<br/> in headers and cookies
      Uncors-->>Client: Data responce
    end