Retrieve AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, and AWS_SESSION_TOKEN from EC2 Instance Metadata

ec2_instance_credentials.sh

#!/bin/sh
set -eu
function json_v () { python -c 'import sys,json;j=json.load(sys.stdin); a=sys.argv[1:]; print("\n".join([j[k] for k in a]))' "$@" ; }
function _ec2_credentials () {
    JSON=`curl -s http://169.254.169.254/latest/meta-data/identity-credentials/ec2/security-credentials/ec2-instance`
    if [ -n "$JSON" ] ; then
        AWS_ACCESS_KEY_ID=`printf "%s" "$JSON" | json_v AccessKeyId`
        AWS_SECRET_ACCESS_KEY=`printf "%s" "$JSON" | json_v SecretAccessKey`
        AWS_SESSION_TOKEN=`printf "%s" "$JSON" | json_v Token`
        export AWS_ACCESS_KEY_ID AWS_SECRET_ACCESS_KEY AWS_SESSION_TOKEN
        return 0
    fi
    return 1
}

_ec2_credentials

# If not sourced into a script ($0 = "-bash"), print values
if [ ! "${0:0:1}" = "-" ] ; then
    printf "AWS_ACCESS_KEY_ID=%s\n" $AWS_ACCESS_KEY_ID
    printf "AWS_SECRET_ACCESS_KEY=%s\n" $AWS_ACCESS_KEY_ID
    printf "AWS_SESSION_TOKEN=%s\n" $AWS_ACCESS_KEY_ID
fi

# If command-line arguments were specified, execute them
if [ $# -gt 0 ] ; then
    exec "$@"
fi