I want to generate SAS URL dynamically via C# code for Azure Blob Container. Using this SAS URL we must be able to upload the files

Question

I want to generate SAS URL dynamically via C# code for Azure Blob Container. Using this SAS URL we must be able to upload the files to the Azure Blob Container. I have tried multiple ways to generate the SAS URL by following the Microsoft docs. But I am always getting AuthorizationResourceTypeMismatch Error or AuthorizationPermissionMismatch.

Error: AuthorizationPermissionMismatch This request is not authorized to perform this operation using this permission.

private static Uri GetServiceSasUriForContainer(BlobContainerClient containerClient,
                                          string storedPolicyName = null)
        {
            // Check whether this BlobContainerClient object has been authorized with Shared Key.
            if (containerClient.CanGenerateSasUri)
            {
                // Create a SAS token that's valid for one hour.
                BlobSasBuilder sasBuilder = new BlobSasBuilder()
                {
                    BlobContainerName = containerClient.Name,
                    Resource = "c"
                };

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

                Uri sasUri = containerClient.GenerateSasUri(sasBuilder);
                Console.WriteLine("SAS URI for blob container is: {0}", sasUri);
                Console.WriteLine();

                return sasUri;
            }
            else
            {
                Console.WriteLine(@"BlobContainerClient must be authorized with Shared Key 
                          credentials to create a service SAS.");
                return null;
            }
        }

Error: AuthenticationFailed Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature.

I need this sas url because I use this url in my javascript to upload files into the Azure Blob Container. Can someone help me out achieving this goal?

Answer 1

The reason you're getting this error is because you are creating the SAS token with Read permission (BlobContainerSasPermissions.Read).

In order to upload a blob in a container using SAS URL, the SAS token needs either Write (BlobContainerSasPermissions.Write) or Create (BlobContainerSasPermissions.Create) permission. Please create a SAS token with one of these permissions and you should not get this error.

To learn more about the permissions, please see this link: https://learn.microsoft.com/en-us/rest/api/storageservices/create-service-sas#permissions-for-a-directory-container-or-blob.