Fun with golang, Google Maps api, and proxying requests

I admire published api code that is thoroughly thought through. Recently I have been working with the Google Maps API in golang and have found that they set it up to allow one to pass in an net/http/client variable which means that it is possible to create a http client which sends the requests via a proxy (such as Fiddle) in order to debug and diagnose challenges with the code.

package main

import (
	"net/http"
	"net/url"
	"crypto/tls"
	"context"

	"googlemaps.github.io/maps"

	"github.com/davecgh/go-spew/spew"
)

func main() {
	APIKey := "[Google API KEY]"
	proxyURL, _ := url.Parse("http://localhost:9999")
	tr := &http.Transport{
		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
		Proxy:           http.ProxyURL(proxyURL),
	}
	client := &http.Client{Transport: tr}

	c, _ := maps.NewClient(
		maps.WithAPIKey(APIKey),
		maps.WithHTTPClient(client),
	)

	r := &maps.GeocodingRequest{
		Address: "1600 Pennsylvania Ave NW",
		Region:  "us",
	}

	resp, e := c.Geocode(context.Background(), r)

	spew.Dump(resp,e)
}

which when executed would return:

$ go run main.go
([]maps.GeocodingResult) (len=1 cap=4) {
 (maps.GeocodingResult) {
  AddressComponents: ([]maps.AddressComponent) (len=7 cap=9) {
   (maps.AddressComponent) {
    LongName: (string) (len=29) "Pennsylvania Avenue Northwest",
    ShortName: (string) (len=19) "Pennsylvania Ave NW",
    Types: ([]string) (len=1 cap=4) {
     (string) (len=5) "route"
    }
   },
   (maps.AddressComponent) {
    LongName: (string) (len=4) "1600",
    ShortName: (string) (len=4) "1600",
    Types: ([]string) (len=1 cap=4) {
     (string) (len=13) "street_number"
    }
   },
   (maps.AddressComponent) {
    LongName: (string) (len=20) "Northwest Washington",
    ShortName: (string) (len=20) "Northwest Washington",
    Types: ([]string) (len=2 cap=4) {
     (string) (len=12) "neighborhood",
     (string) (len=9) "political"
    }
   },
   (maps.AddressComponent) {
    LongName: (string) (len=10) "Washington",
    ShortName: (string) (len=10) "Washington",
    Types: ([]string) (len=2 cap=4) {
     (string) (len=8) "locality",
     (string) (len=9) "political"
    }
   },
   (maps.AddressComponent) {
    LongName: (string) (len=20) "District of Columbia",
    ShortName: (string) (len=2) "DC",
    Types: ([]string) (len=2 cap=4) {
     (string) (len=27) "administrative_area_level_1",
     (string) (len=9) "political"
    }
   },
   (maps.AddressComponent) {
    LongName: (string) (len=13) "United States",
    ShortName: (string) (len=2) "US",
    Types: ([]string) (len=2 cap=4) {
     (string) (len=7) "country",
     (string) (len=9) "political"
    }
   },
   (maps.AddressComponent) {
    LongName: (string) (len=5) "20500",
    ShortName: (string) (len=5) "20500",
    Types: ([]string) (len=1 cap=4) {
     (string) (len=11) "postal_code"
    }
   }
  },
  FormattedAddress: (string) (len=51) "1600 Pennsylvania Ave NW, Washington, DC 20500, USA",
  Geometry: (maps.AddressGeometry) {
   Location: (maps.LatLng) 38.8976633,-77.0365739,
   LocationType: (string) (len=7) "ROOFTOP",
   Bounds: (maps.LatLngBounds) 38.8973063,-77.03795749999999|38.8979044,-77.0355124,
   Viewport: (maps.LatLngBounds) 38.8962604197085,-77.0380839302915|38.8989583802915,-77.03538596970849,
   Types: ([]string) <nil>
  },
  Types: ([]string) (len=3 cap=4) {
   (string) (len=13) "establishment",
   (string) (len=17) "point_of_interest",
   (string) (len=7) "premise"
  },
  PlaceID: (string) (len=27) "ChIJGVtI4by3t4kRr51d_Qm_x58"
 }
}
(interface {}) <nil>

In the proxy we see the request:

GET https://maps.googleapis.com/maps/api/geocode/json?address=1600+Pennsylvania+Ave+NW&key=[REDACTED]&region=us HTTP/1.1
Host: maps.googleapis.com
User-Agent: GoogleGeoApiClientGo/0.1
Accept-Encoding: gzip

with the corresponding response:

HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Date: Thu, 31 Aug 2017 18:53:31 GMT
Expires: Fri, 01 Sep 2017 18:53:31 GMT
Cache-Control: public, max-age=86400
Vary: Accept-Language
Access-Control-Allow-Origin: *
Server: mafe
Content-Length: 2319
X-XSS-Protection: 1; mode=block
X-Frame-Options: SAMEORIGIN
Alt-Svc: quic=":443"; ma=2592000; v="39,38,37,35"

{
   "results" : [
      {
         "address_components" : [
            {
               "long_name" : "Pennsylvania Avenue Northwest",
               "short_name" : "Pennsylvania Ave NW",
               "types" : [ "route" ]
            },
            {
               "long_name" : "1600",
               "short_name" : "1600",
               "types" : [ "street_number" ]
            },
            {
               "long_name" : "Northwest Washington",
               "short_name" : "Northwest Washington",
               "types" : [ "neighborhood", "political" ]
            },
            {
               "long_name" : "Washington",
               "short_name" : "Washington",
               "types" : [ "locality", "political" ]
            },
            {
               "long_name" : "District of Columbia",
               "short_name" : "DC",
               "types" : [ "administrative_area_level_1", "political" ]
            },
            {
               "long_name" : "United States",
               "short_name" : "US",
               "types" : [ "country", "political" ]
            },
            {
               "long_name" : "20500",
               "short_name" : "20500",
               "types" : [ "postal_code" ]
            }
         ],
         "formatted_address" : "1600 Pennsylvania Ave NW, Washington, DC 20500, USA",
         "geometry" : {
            "bounds" : {
               "northeast" : {
                  "lat" : 38.8979044,
                  "lng" : -77.0355124
               },
               "southwest" : {
                  "lat" : 38.8973063,
                  "lng" : -77.03795749999999
               }
            },
            "location" : {
               "lat" : 38.8976633,
               "lng" : -77.03657389999999
            },
            "location_type" : "ROOFTOP",
            "viewport" : {
               "northeast" : {
                  "lat" : 38.8989583802915,
                  "lng" : -77.03538596970849
               },
               "southwest" : {
                  "lat" : 38.8962604197085,
                  "lng" : -77.03808393029151
               }
            }
         },
         "place_id" : "ChIJGVtI4by3t4kRr51d_Qm_x58",
         "types" : [ "establishment", "point_of_interest", "premise" ]
      }
   ],
   "status" : "OK"
}