Golang : Get S3 or CloudFront object or file information

Here is a simple example on how to get the S3, CloudFront object (in fact, any file accessible from URL) information. Information such as Etag, X-Amz-Storage-Class, Last-Modified, Cache-Control or Content-Type values. This information is also known as metadata.

 package main

 import (
 "fmt"
 "net/http"
 "os"
 )

 func main() {
 url := "https://d1ohg4ss876yi2.cloudfront.net/preview/golang.png"

 response, err := http.Head(url)
 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 // Is our request ok?

 if response.StatusCode != http.StatusOK {
 fmt.Println(response.Status)
 os.Exit(1)
 // exit if not ok
 }

 for k, v := range response.Header {
 fmt.Println("Header :", k, " : ", v)
 }
 }

Sample output :

Header : Age : [1198]

Header : Etag : ["11ef76eda4cd556455088d69eb95bdc2"]

Header : Server : [AmazonS3]

Header : Date : [Wed, 18 Nov 2015 08:19:31 GMT]

Header : Cache-Control : [max-age=315360000]

Header : Last-Modified : [Fri, 13 Nov 2015 09:44:33 GMT]

Header : X-Cache : [Hit from cloudfront]

Header : Via : [1.1 04fb12f896eac18e91eac3e60e276ed8.cloudfront.net (CloudFront)]

Header : X-Amz-Cf-Id : [J7qrcfGsa9vssCAkavL8v8zqn1JMU4PneP2aMY4LyEKSLIRRREfg==]

Header : Content-Length : [113857]

Header : Connection : [keep-alive]

Header : Accept-Ranges : [bytes]

Header : Content-Type : [image/png]

Header : X-Amz-Storage-Class : [REDUCED_REDUNDANCY]