Azure App Service - write to filesystem - ASP.NET web application

5
votes

I have an ASP.NET web application, created in Visual Studio 2017.

In the application there is a form, where the users can upload files. When files are uploaded, I process them and I save them on the filesystem:

var photo = Request.Files["file"];
photo.SaveAs("D:\\home");

Everything works perfect locally, but it's not working when I deploy the App on Azure App Services.

I read that, on Azure, the path

D:\home

should be writable.

But when I try the code I get this error:

Access to the path 'd:\home\test_image.JPG' is denied.
2
asp.netazurefile-ioazure-web-app-service
d:\home probably doesn't (even) exist. Have a look at @sprinter252 's answer, or get the temp folder, or use storage. - rickvdbosch

2 Answers

7
votes

Use %TEMP%, which on Azure App Service (Windows) resolves to d:\local. That's the local machine disk, not network storage, so significantly faster. It gets wiped on app restart so code accordingly.

var tempDirectoryPath = Environment.GetEnvironmentVariable("TEMP");
var filePath = Path.Combine(tempDirectoryPath, Request.Files["file"]);

If you want durability use Blob Storage instead.

3
votes

You should never use absolute paths on server components. Try something like this for instance

var folder = Environment.GetFolderPath(System.Environment.SpecialFolder.CommonApplicationData);
var filePath = Path.Combine(folder, Request.Files["file"]);