Groovy RESTClient, headers and authentication

I recently wanted to write some REST API calls with groovy and was using groovyx.net.http.RESTClient that is part of the HTTP Builder library (http://groovy.codehaus.org/modules/http-builder/doc/rest.html). There's not a ton of documentation on it and I was struggling to find out how to do basic authentication with it, as well as how to set headers. I finally tracked some code down on the groovy mailing list and I thought I'd detail how to do it here to help anyone else who may be looking for direct instructions how to do it. I will use the basecamp API (https://github.com/37signals/bcx-api) as an example since that's the API I was writing against (https://github.com/37signals/bcx-api). The authentication is passed by simply setting restClientInstance.auth.basic with your username and password, e.g.

def restClient = new RESTClient(...)
restClient.auth.basic "me", "password"

Headers can be set in 2 ways: by passing a map of headers when running a request, e.g.

def restClient = new RESTClient(...)
def response = restClient.get(
                   path: "projects.json",
                   headers: ["User-Agent": "My basecamp application (myemail@domain.com)"]
                )

And if you want to set a header to use on every request to the REST service, you can set default headers on the RESTClient instance, e.g.

def restClient = new RESTClient(...)
restClient.defaultRequestHeaders.'User-Agent' = "My basecamp application (myemail@domain.com)"
def response = restClient.get(path: "projects.json")

Here is a full script demonstrating how to call the projects endpoint on the basecamp api using RESTClient:

#! /usr/bin/env groovy

@Grab(group='org.codehaus.groovy.modules.http-builder', module='http-builder', version='0.5.2' )

import static groovyx.net.http.ContentType.JSON

import groovyx.net.http.RESTClient
import groovy.util.slurpersupport.GPathResult
import static groovyx.net.http.ContentType.URLENC


def accountId = "yourAccountId" // this is the number after http://basecamp.com when logged into the basecamp website e.g. http://basecamp.com/1234567
def userName = "basecampUserName"
def password = "basecampPassword"

def basecamp = new RESTClient( "https://basecamp.com/${accountId}/api/v1/".toString() )
basecamp.auth.basic userName, password

def response = basecamp.get(
                   path: "projects.json",
                   headers: ["User-Agent": "My basecamp application (myemail@domain.com)"]
                )
println response.data.toString(2)