#!/bin/bash
# Inspired by http://dl.getipaddr.net/ and http://curl.haxx.se/mail/archive-2014-10/0006.html
file=path/to/file
bucket=your-bucket
contentType="application/octet-stream"
dateValue=`date -R`
resource="/${bucket}/${file}"
s3Key=`curl -s http://169.254.169.254/latest/meta-data/iam/security-credentials/ec2-app-role | grep 'AccessKeyId' | sed 's/.* "\([^"]*\).*/\1/'`
s3Secret=`curl -s http://169.254.169.254/latest/meta-data/iam/security-credentials/ec2-app-role | grep 'SecretAccessKey' | sed 's/.* "\([^"]*\).*/\1/'`
token=`curl -s http://169.254.169.254/latest/meta-data/iam/security-credentials/ec2-app-role | grep 'Token' | sed 's/.* "\([^"]*\).*/\1/'`
stringToSign="GET\n\n${contentType}\n${dateValue}\nx-amz-security-token:${token}\n${resource}"
signature=`echo -en ${stringToSign} | openssl sha1 -hmac ${s3Secret} -binary | base64`
curlOut=$(curl -s -w "%{speed_download}" -o /dev/null -X GET -H "Host: ${bucket}.s3.amazonaws.com" -H "Date: ${dateValue}" -H "Content-Type: ${contentType}" -H "Authorization: AWS ${s3Key}:${signature}" -H "x-amz-security-token: ${token}" https://${bucket}.s3.amazonaws.com/${file})
# Output x-fer speed in MB/sec
echo "scale=2;$curlOut/1048576" | bc -q