deploy magento on elastic beanstalk with composer post install command to write production config

composer.json

{
    "require": {
        "magento-hackathon/magento-composer-installer": "3.0.*",
        "aydin-hassan/magento-core-composer-installer": "^1.3",
        "firegento/magento": "1.9.2.2"
    },
    "extra": {
        "magento-root-dir": "htdocs",
        "auto-append-gitignore": true,
        "magento-deploystrategy": "copy",
        "magento-force": true
     },
     "scripts": {
        "post-install-cmd": [
            "bash postupstall.sh"
        ],
        "post-update-cmd": [
            "bash postupstall.sh"
        ]
    }
}

postupstall.sh

#!/bin/bash

# ondeck is the temp deploy folder of elastic beanstalk
if [ "$PWD" = "/var/app/ondeck" ]
then
	cp -rf ./htdocs/app/etc/local.production.xml ./htdocs/app/etc/local.xml
fi

exit 0