A bash script which supports uploading blobs to Azure Storage: ./upload-to-azure.sh [filename]

upload-to-azure.sh

#!/usr/bin/env bash

FILENAME=${1}
# expected to be defined in the environment
#  - AZURE_STORAGE_ACCOUNT
#  - AZURE_CONTAINER_NAME
#  - AZURE_ACCESS_KEY

# inspired by
# https://stackoverflow.com/questions/20103258/accessing-azure-blob-storage-using-bash-curl

authorization="SharedKey"

HTTP_METHOD="PUT"
request_date=$(TZ=GMT date "+%a, %d %h %Y %H:%M:%S %Z")
storage_service_version="2015-02-21"

# HTTP Request headers
x_ms_date_h="x-ms-date:$request_date"
x_ms_version_h="x-ms-version:$storage_service_version"
x_ms_blob_type_h="x-ms-blob-type:BlockBlob"

FILE_LENGTH=$(wc --bytes < ${FILENAME})
FILE_TYPE=$(file --mime-type -b ${FILENAME})
FILE_MD5=$(md5sum -b ${FILENAME} | awk '{ print $1 }')

# Build the signature string
canonicalized_headers="${x_ms_blob_type_h}\n${x_ms_date_h}\n${x_ms_version_h}"
canonicalized_resource="/${AZURE_STORAGE_ACCOUNT}/${AZURE_CONTAINER_NAME}/${FILE_MD5}"

#######
# From: https://docs.microsoft.com/en-us/rest/api/storageservices/authentication-for-the-azure-storage-services
#
#StringToSign = VERB + "\n" +
#               Content-Encoding + "\n" +
#               Content-Language + "\n" +
#               Content-Length + "\n" +
#               Content-MD5 + "\n" +
#               Content-Type + "\n" +
#               Date + "\n" +
#               If-Modified-Since + "\n" +
#               If-Match + "\n" +
#               If-None-Match + "\n" +
#               If-Unmodified-Since + "\n" +
#               Range + "\n" +
#               CanonicalizedHeaders +
#               CanonicalizedResource;
string_to_sign="${HTTP_METHOD}\n\n\n${FILE_LENGTH}\n\n${FILE_TYPE}\n\n\n\n\n\n\n${canonicalized_headers}\n${canonicalized_resource}"

# Decode the Base64 encoded access key, convert to Hex.
decoded_hex_key="$(echo -n $AZURE_ACCESS_KEY | base64 -d -w0 | xxd -p -c256)"

# Create the HMAC signature for the Authorization header
signature=$(printf  "$string_to_sign" | openssl dgst -sha256 -mac HMAC -macopt "hexkey:$decoded_hex_key" -binary | base64 -w0)

authorization_header="Authorization: $authorization $AZURE_STORAGE_ACCOUNT:$signature"
OUTPUT_FILE="https://${AZURE_STORAGE_ACCOUNT}.blob.core.windows.net/${AZURE_CONTAINER_NAME}/${FILE_MD5}"

curl -X ${HTTP_METHOD} \
    -T ${FILENAME} \
    -H "$x_ms_date_h" \
    -H "$x_ms_version_h" \
    -H "$x_ms_blob_type_h" \
    -H "$authorization_header" \
    -H "Content-Type: ${FILE_TYPE}" \
    ${OUTPUT_FILE}

if [ $? -eq 0 ]; then
    echo ${OUTPUT_FILE}
    exit 0;
fi;
exit 1

This code works completely fine... But my requirement is i need to push 0 byte file to azure blob storage. when i try to do that, it is throwing an error. does someone have any idea what i need to change in this script ?