package main

import (
    "fmt"
    "log"
    "time"

    "github.com/aws/aws-sdk-go/aws"
    "github.com/aws/aws-sdk-go/aws/session"
    "github.com/aws/aws-sdk-go/service/s3"
    "github.com/kelseyhightower/envconfig"
)

func main() {
    configuration := s3.PutObjectInput{ Key: aws.String("default_key") }

    // Add Bucket to configuration from environment variable
    // e.g:
    //    CONFIGURATION_BUCKET -> configuration.Bucket
    err := envconfig.Process("configuration", &configuration)

    if err != nil {
        log.Fatal(err.Error())
    }

    sess := session.Must(session.NewSessionWithOptions(session.Options{
      SharedConfigState: session.SharedConfigEnable,
    }))
    svc := s3.New(sess)
    req, _ := svc.PutObjectRequest(&configuration)

    url, err := req.Presign(15 * time.Minute)

    if err != nil {
        log.Fatal(err.Error())
    }
    fmt.Println("Url is", url)
}

fmt.Println(configuration.Bucket, configuration.Key) // returns address