Use aws4sign.py to list AWS Route53 zones

aws-route53-zones.sh

# AWS keys
export AWS_ACCESS_KEY_ID=...
export AWS_SECRET_ACCESS_KEY=...

# Inputs to the signature algorithm; must be immutable
#
# The $now parameter in particular is interesting. The AWS signature algorithm
# includes the current time, which we pass to aws4sign.py using the -t option.
now=$(date '+%s')
url=https://route53.amazonaws.com/2013-04-01/hostedzone

# Compute all headers
auth_header=$(python2.7 ./aws4sign.py -t $now -p authorization $url | cut -f2)
date_header=$(python2.7 ./aws4sign.py -t $now -p x-amz-date $url | cut -f2)
content_header=$(python2.7 ./aws4sign.py -t $now -p x-amz-content-sha256 $url | cut -f2)

curl -s \
    -H "authorization: $auth_header" \
    -H "x-amz-date: $date_header" \
    -H "x-amz-content-sha256: $content_header" \
    $url