Azure Communication Service Email sending by curl

sendacsmail.sh

#!/bin/sh
set -Ceu

# ACS Email API
# https://learn.microsoft.com/en-us/rest/api/communication/email/email/send?view=rest-communication-email-2023-03-31&tabs=HTTP

# How to sign the request
# https://learn.microsoft.com/en-us/rest/api/communication/authentication#signing-an-http-request

# Common headers
# https://learn.microsoft.com/en-us/rest/api/communication/headers

# Repeatability of requests
# https://learn.microsoft.com/en-us/rest/api/communication/repeatable-requests

# See also
# https://learn.microsoft.com/en-us/azure/azure-app-configuration/rest-api-authentication-hmac#bash
# https://stackoverflow.com/questions/20103258/accessing-azure-blob-storage-using-bash-curl


# Parameters from ACS resource
########################################

# https://learn.microsoft.com/en-us/azure/communication-services/quickstarts/email/send-email?tabs=windows%2Cconnection-string%2Csend-email-and-get-status-async%2Csync-client&pivots=platform-azportal

# Replace <YourSecret> with actual secret from ACS resource.
secret="<YourSecret>"
# secret="7W9ichYxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

# Replace <YourHost> with actual endpoint host from ACS resource. Eg: <ResourceName>.<region>.communication.azure.com
host="<YourHost>"
# host="xxxxxxxxxxxxxxxxxxxxxxx.japan.communication.azure.com"

# Replace <YourMailFromAddress> with the MailFrom address of your verified domain. Eg: [email protected]
senderAddress="<YourMailFromAddress>"
# senderAddress="[email protected]"

# Replace <RecipientAddress> with the email address you would like to send a message to.
recipientAddress="<RecipientAddress>"
# recipientAddress="[email protected]"

########################################


body=$(cat <<EOF
{
  "Recipients": {
    "To": [
      {
        "DisplayName": "",
        "address": "${recipientAddress}"
      }
    ]
  },
  "Content": {
    "Subject": "ACS mail from shell script with curl",
    "PlainText": "こんにちは💛"
  },
  "SenderAddress": "${senderAddress}"
}
EOF
)

path="/emails:send?api-version=2023-03-31"
method="POST"
uuid=$(uuidgen)
gmt=$(date -u +"%a, %d %b %Y %H:%M:%S GMT")

contentHash=$(echo -n "$body" | openssl dgst -sha256 -binary | base64 -w0)
# echo $contentHash

stringToSign="${method}
${path}
${gmt};${host};${contentHash}"
# echo -n "${stringToSign}"

decodedHexkey="$(echo -n $secret | base64 -d -w0 | xxd -p -c256)"

signature=$(echo -n "${stringToSign}" | openssl dgst -binary -sha256 -mac HMAC -macopt "hexkey:${decodedHexkey}" | base64 -w0)
# echo -n $signature

curl -X $method "https://$host$path" \
  -H "x-ms-content-sha256: ${contentHash}" \
  -H "Authorization: HMAC-SHA256 SignedHeaders=x-ms-date;host;x-ms-content-sha256&Signature=$signature" \
  -H "x-ms-date: $gmt" \
  -H "Content-Type: application/json" \
  -H "repeatability-first-sent: $gmt" \
  -H "repeatability-request-id: $uuid" \
  -d "$body"