golang-restclient

Restful

A Rest Client for Go (Golang)

========

An extremely simple to use, lightweight, yet powerful REST Client

Motivation

The Go http standard library is a great library, but it might sometimes be a bit too low level to use, and it doesn't offer features like fork-join requests for better performance, response caching based on headers, and the possibility to mockup responses.

Features and Roadmap

v0.1

• GET, POST, PUT, PATCH, DELETE, HEAD & OPTIONS HTTP verbs
• Dead simple, synchronous requests
• Automatic caching of hosts connections
• Response Caching, based on response headers (cache-control, last-modified, etag, expires)
• Local caching strategies: TTL, LRU & Max Byte Size.
• Mockups!
• Fork-Join request pattern, for sending many requests concurrently, improving client perfomance.
• Async request pattern.
• Request Body can be string, []byte, struct & map.
• Automatic marshal and unmarshal for JSON and XML Content-Type. Default JSON.
• Full access to http.Response object.
• Retries
• BasicAuth
• UserAgent
• Gzip support
• HTTP/2 support (automatic with Go +1.6)

v0.2

• Connection usage metrics
• Response Time metrics
• Brotli Content-Encoding Responses support - http://google-opensource.blogspot.com.ar/2015/09/introducing-brotli-new-compression.html

v0.3

• Custom Root Certificates and Client Certificates
• Testing +95%

v0.4

• Plugable external caches like Memcached

Caching

Caching is done by two strategies working together: Time To Live (TTL) and Least Recently Used (LRU). Objects are inserted in the cache based on Response Headers. You can establish a maximum Memory Size for the cache and objects are flushed based on time expiration (TTL) or by hitting the maximum memory limit. In the last case, least accessed objects will be removed first.

Examples

Installation

clone en tu gopath o goroot

git clone https://github.com/mercadolibre/golang-restclient/

Importing

import "github.com/mercadolibre/golang-restclient/rest"

Simple GET

resp := rest.Get("https://api.restfulsite.com/resource")

Simple POST

// Using a `string` as body
resp := rest.Post("https://api.restfulsite.com/resource", "Body")

Simple POST, with Struct Body

type User struct {
	Id   int    `json:"id"`
	Name string `json:"name"`
}

body := new(User)
body.Id = 1
body.Name = "Hernan"

// body will be marshall as JSON
resp := rest.Post("https://api.restfulsite.com/resource/1", body)
fmt.Println(resp)

Fork Join

ForkJoin let you fork requests, and wait until all of them have return.

Concurrent has methods for Get, Post, Put, Patch, Delete, Head & Options, with the almost the same API as the synchronous methods. The difference is that these methods return a FutureResponse, which holds a pointer to Response. Response inside FutureResponse is nil until request has finished.

var f [3]*rest.FutureResponse

// ForkJoin will send all requests concurrently
// and will wait until all requests have their correspondent responses
rest.ForkJoin(func(c *rest.Concurrent) {
	f[0] = c.Get("https://api.restfulsite.com/resource/1")
	f[1] = c.Get("https://api.restfulsite.com/resource/2")
	f[2] = c.Get("https://api.restfulsite.com/resource/3")
})

for i := range f {
  if f[i].Response().StatusCode == http.StatusOK {
    fmt.Println(f[i].Response())
  }
}

Async

Async let you make Restful requests in an asynchronous way, without blocking the go routine calling the Async function.

Whenever the Response is ready, the f function will be called back.

// This won't be blocked.
rest.AsyncGet("https://api.restfulsite.com/user", func(r *rest.Response) {
	if r.StatusCode == http.StatusOK {
		fmt.Println(r)
	}
})

// This will be printed first.
fmt.Println("print first")

Defaults

• Headers: keep-alive, Cache-Control: no-cache
• Timeout: 2 seconds
• ContentType: JSON (for body requests in POST, PUT and PATCH)
• Cache: enable
• Cache Size: 1GB
• Idle Connections Per Host: 2 (the default of http.net package)
• HTTP/2: automatic with Go 1.6
• Gzip: automatic support for gzip responses

RequestBuilder

RequestBuilder gives you the power to go beyond defaults. It is possible to set up headers, timeout, baseURL, proxy, contentType, not to use cache, directly disabling timeout (in an explicit way), and setting max idle connections.

// You can reuse in every RequestBuilder
customPool := &rest.CustomPool{
	MaxIdleConnsPerHost: 100,
}

headers := make(http.Header)
headers.Add("myHeader", "myValue")

var rb = rest.RequestBuilder{
	Headers:             headers,
	Timeout:             200 * time.Millisecond,
	BaseURL:             "https://baseURL",
	Proxy:               "http://myproxy",
	ContentType:         rest.JSON,
	DisableCache:        false,
	DisableTimeout:      false,
	MaxIdleConnsPerHost: 10,
	CustomPool:     customPool,
}

resp := rb.Get("/mypath")

Mockups

When using mockups all requests will be sent to the mockup server.

To activate the mockup environment you need to programmatically start the mockup server

StartMockupServer()

A mockup example

myURL := "http://mytest.com/foo"

myHeaders := make(http.Header)
myHeaders.Add("Hello", "world")

mock := rest.Mock{
	URL:          myURL,
	HTTPMethod:   http.MethodGet,
	ReqHeaders:   myHeaders,
	RespHTTPCode: http.StatusOK,
	RespBody:     "foo",
}

rest.AddMockups(&mock)

v := rest.Get(myURL)