Download S3 objects with only curl

curl_object_downloader.sh

#!/bin/bash

# Example:
# for minio: in k9s, forward ports 9000 and 9001 to localhost
# ./curl_object_downloader.sh localhost:9000 mykey_id mykey_secret \
#   mybucket mypath/myobj.bin ./myobj.bin

# User Minio Vars
URL=$1
USERNAME=$2
PASSWORD=$3
BUCKET=$4
MINIO_PATH="/${BUCKET}/$5"
OUT_FILE=$6

# Static Vars
DATE=$(date -R --utc)
CONTENT_TYPE='application/zstd'
SIG_STRING="GET\n\n${CONTENT_TYPE}\n${DATE}\n${MINIO_PATH}"
SIGNATURE=`echo -en ${SIG_STRING} | openssl sha1 -hmac ${PASSWORD} -binary | base64`


curl -o "${OUT_FILE}" \
    -H "Host: $URL" \
    -H "Date: ${DATE}" \
    -H "Content-Type: ${CONTENT_TYPE}" \
    -H "Authorization: AWS ${USERNAME}:${SIGNATURE}" \
    http://$URL${MINIO_PATH}