How to List Blobs in a Container iwth C# API using a SAS token-CodePudding

I am using a SAS token to access Azure Blob Store using the c# API. I can successfully create new blobs in a container and, given the name of a blob, I can read that blob and get the contents. However, I am unable to LIST the blobs in the container as I get an InvalidURl error: The requested URI does not represent any resource on the server.

I am using the same sas URI for all three requests, upload, download, and list.

I generate the sas URI using the following code:

if (containerClient.CanGenerateSasUri)
{
     BlobSasBuilder sasBuilder = new BlobSasBuilder()
    {
        BlobContainerName = containerClient.Name,
        Resource = "c"
    };

    if (storedPolicyName == null)
    {
        sasBuilder.ExpiresOn = DateTimeOffset.UtcNow.AddHours(1);
        sasBuilder.SetPermissions(BlobContainerSasPermissions.All);
    }
    else
    {
        sasBuilder.Identifier = storedPolicyName;
    }

    Uri sasUri = containerClient.GenerateSasUri(sasBuilder);
}

And I attempt to list the names of the blobs using the folowing code:

    var serviceClient = new BlobServiceClient(sasUri);
    var containerClient = serviceClient.GetBlobContainerClient(container);
    var blobs = containerClient.GetBlobsByHierarchyAsync();

    await foreach (var blob in blobs)
    {
        if (blob.IsBlob)
        {
            blobNames.Add(blob.Blob.Name);
        }           
    }

If I create the BlobServiceClient using the connection string (rather than a sas URI), then this code works and can list the blobs that I have uploaded using the sas URI, but using the sas URI fails with InvalidURL (even though is the same sas token that I just used to create the blob in the container and it has permissions to list blobs in the container).

If I hard code a known filename I can use the sas containerClient to create a working BlobClient:

    var blobClient = containerClient.GetBlobClient("blobname");
    if (await blobClient.ExistsAsync())
    {
        var stream = await blobClient.DownloadStreamingAsync();
        return stream.Value.Content;
    }

What do I need to do to get the List operation to work with the sas token? Any pointers to what I'm missing greatly appreciated!

CodePudding user response：

The reason you are running into issues is because you are using a Blob Container SAS URI to create BlobServiceClient and when you create a BlobContainerClient instance using the service client, the container name is repeated twice.

Possible solutions:

Directly create an instance of BlobContainerClient using the container SAS URL. You can do something like:

containerClient = new BlobContainerClient(sasUri);

Create an instance of BlobServiceClient using just the SAS token (and not SAS URL) and account endpoint. You can do something like:

var endpoint = $"{uri.Scheme}://{uri.Host}";
var sasToken = uri.Query;
var credentials = new AzureSasCredential(sasToken);
var serviceClient = new BlobServiceClient(new Uri(endpoint), credentials);
var containerClient = serviceClient.GetBlobContainerClient(container);
...
...rest of your code
...