Transfer file from Azure Blob Storage to Google Cloud Storage programmatically
<p>I have a number of files that I transferred into Azure Blob Storage via the Azure Data Factory. Unfortunately, this tool doesn't appear to set the Content-MD5 value for any of the values, so when I pull that value from the Blob Storage API, it's empty.</p>

<p>I'm aiming to transfer these files out of Azure Blob Storage and into Google Storage. The documentation I'm seeing for Google's Storagetransfer service at <a href="https://cloud.google.com/storage/transfer/reference/rest/v1/TransferSpec#HttpData" rel="nofollow noreferrer">https://cloud.google.com/storage/transfer/reference/rest/v1/TransferSpec#HttpData</a> indicates that I can easily initiate such a transfer if I supply a list of the files with their URL, length in bytes and an MD5 hash of each.</p>

<p>Well, I can easily pull the first two from Azure Storage, but the third doesn't appear to automatically get populated by Azure Storage, nor can I find any way to get it to do so.</p>

<p>Unfortunately, my other options look limited. In the possibilities so far:</p>

<ol>
<li>Download file to local machine, determine the hash and update the Blob MD5 value </li>
<li>See if I can't write an Azure Functions app in the same region that can calculate the hash value and write it to the blob for each in the container </li>
<li>Use an Amazon S3 egress from Data Factory and then use Google's support for importing from S3 to pull it from there, per <a href="https://cloud.google.com/storage/transfer/reference/rest/v1/TransferSpec#AwsS3Data" rel="nofollow noreferrer">https://cloud.google.com/storage/transfer/reference/rest/v1/TransferSpec#AwsS3Data</a> but this really seems like a waste of bandwidth (and I'd have to set up an Amazon account).</li>
</ol>

<p>Ideally, I want to be able to write a script, hit go and leave it alone. I don't have the fastest download rate from Azure, so #1 would be less than desireable as it'd take a long time.</p>

<p>Have any other approaches?</p>