Backup multiple dokku postgres instances and upload them to a bucket in S3

backup.sh

#!/bin/bash

S3KEY="CHANGE_ME"
S3SECRET="CHANGE_ME"
bucket='CHANGE_ME'
region='CHANGE_ME'

declare -a apps=("app1" "app2")

echo "Starting to backup - $(date)"

function putS3
{
  path=$1
  file=$2
  aws_path=$3
  date=$(date +"%a, %d %b %Y %T %z")
  acl="x-amz-acl:private"
  string="PUT\n\n$content_type\n$date\n$acl\n/$bucket$aws_path$file"
  signature=$(echo -en "${string}" | openssl sha1 -hmac "${S3SECRET}" $
  curl -X PUT -T "$path/$file" \
    -H "Host: $bucket.s3.amazonaws.com" \
    -H "Date: $date" \
    -H "Content-Type: $content_type" \
    -H "$acl" \
    -H "Authorization: AWS ${S3KEY}:$signature" \
    "https://$bucket.$region.amazonaws.com$aws_path$file"
}

d=$(date +"%d-%m-%Y")

for app in "${apps[@]}"
do
        echo "Backing up ${app}"
        file_name="${app}-${d}.dump"
        echo $(dokku postgres:export $app > $file_name)
        echo "Uploading to S3"
        putS3 "." $file_name "/${d}/"
done

echo "Backup Completed - $(date)"