Upload blob with Set-AzStorageBlobContent via pipeline and set ContentType property - azure

Question

Using the Az PowerShell module, I'm trying to enumerate a directory on disk and pipe the output to Set-AzStorageBlobContent to upload to Azure, while preserving the folder structure. This works great, except the ContentType property of all blobs is set to application/octet-stream. I'd like to set it dynamically based on the file extension of the blob being uploaded.
Here's example code for the base case:
Get-ChildItem $SourceRoot -Recurse -File |
Set-AzStorageBlobContent -Container $ContainerName -Context $context -Force
To set the ContentType, I need to add a Properties parameter to Set-AzStorageBlobContent with a value like #{ "ContentType" = "<content type>" }. The content type should be determined from the specific file extension being uploaded. I've written a separate pipelined function that can add a MimeType property to the file object, but I can't figure out how to reference that for the parameter in the pipeline. Example:
function Add-MimeType{
[cmdletbinding()]
param(
[parameter(
Mandatory = $true,
ValueFromPipeline = $true)]
$pipelineInput
)
Process {
$mimeType = Get-MimeType $pipelineInput.Extension
Add-Member -InputObject $pipelineInput -NotePropertyName "MimeType" -NotePropertyValue $mimeType
return $pipelineInput
}
}
function Get-MimeType(
[string]$FileExtension
)
{
switch ($FileExtension.ToLowerInvariant())
{
'.txt' { return 'text/plain' }
'.xml' { return 'text/xml' }
default { return 'application/octet-stream' }
}
}
Get-ChildItem $SourceRoot -Recurse -File |
Add-MimeType |
Set-AzStorageBlobContent -Container $ContainerName -Properties #{"ContentType" = "$($_.MimeType)"} -Context $context -Force
It seems that $_ isn't usable in this context. Is there another way to accomplish this?
The reason I'd like to continue using pipelining is that it appears to work much faster than using a ForEach-Object loop to call the function (where $_ does work).

Answer 1

If you are open to completely different solutions, you can also use AzCopy.
You can upload your whole folder with one command, and AzCopy can also automatically guess the correct mime type based on the file extension. There is also support for Azure Pipelines, if that is part of your setup.
Command could look something like this:
# AzCopy v10 will automatically guess the content type unless you pass --no-guess-mime-type
azcopy copy 'C:\myDirectory' 'https://mystorageaccount.blob.core.windows.net/mycontainer' --recursive
# AzCopy V8
azcopy copy 'C:\myDirectory' 'https://mystorageaccount.blob.core.windows.net/mycontainer' /s /SetContentType
Taken from the output of AzCopy.exe copy --help:
AzCopy automatically detects the content type of the files when uploading from the local disk, based on the file extension or content (if no extension is specified).
The built-in lookup table is small, but on Unix, it is augmented by the local system's mime.types file(s) if available under one or more of these names:
/etc/mime.types
/etc/apache2/mime.types
/etc/apache/mime.types
On Windows, MIME types are extracted from the registry. This feature can be turned off with the help of a flag. Please refer to the flag section.