.NET Core 3.1 API works fine locally but doesn't after deployment

Question

In a Web-Application, written in C# in .NET Core 3.1, i want to Display a Datatable of all the Blobs in one of our Company's Azure Blob Storages. For this i'm using Datatables.net in the Frontend with Ajax-Calls which target a selfwritten API in the same Web-App. The API should get all the searched Blobs, format them for easier viewing and then give them back to the Table. Locally it really works like a charm. However, soon after deployment i noticed that the Ajax-Call just simply returns a 404 Response.

For reference:

My API-Controller

[Route("Blob/api/[controller]")]
[ApiController]
public class BlobsController : ControllerBase
{
    private readonly string _connectionString;
    private readonly string _container;
    private readonly BlobContainerClient _client;


    public BlobsController(IConfiguration configuration)
    {
        IEnumerable<IConfigurationSection> _blobStorageSection = configuration.GetSection("BlobStorage").GetChildren();
        _connectionString = _blobStorageSection.Single(e => e.Key == "ConnectionString").Value;
        _container = _blobStorageSection.Single(e => e.Key == "ContainerName").Value;
        _client = new BlobContainerClient(_connectionString, _container);
    }

    [HttpGet("{EncodedDelimiter}/{EncodedPrefix}")]
    public ActionResult GetBlobs(string EncodedDelimiter, string EncodedPrefix)
    {
        if (! StorageIsAvailable())
            return NotFound();

        string Delimiter = WebUtility.UrlDecode(EncodedDelimiter);
        string Prefix = WebUtility.UrlDecode(EncodedPrefix);

        Pageable<BlobHierarchyItem> BlobHierarchy = _client.GetBlobsByHierarchy(delimiter: Delimiter, prefix: Prefix);

        return Ok(EnrichBlobList(BlobHierarchy));
    }

    [HttpGet("init/{EncodedDelimiter}")]
    public ActionResult Initialize(string EncodedDelimiter)
    {
        if (! StorageIsAvailable())
            return NotFound();

        string Delimiter = WebUtility.UrlDecode(EncodedDelimiter);

        Pageable<BlobHierarchyItem> BlobHierarchy = _client.GetBlobsByHierarchy(delimiter: Delimiter);

        return Ok(EnrichBlobList(BlobHierarchy));
    }

Here the Ajax-Call Snippet

 var Table = $("#BlobTable").DataTable({
        ajax:{
            url: "api/Blobs/init/%2F",
            dataSrc: ""
        },
        processing: true,
        columnDefs:[
            {
                "targets": 0,
                "data": "standartizedName",
            },
            {
                "targets": 1,
                "data": null,
                "render": function(full){
                    return renderTyp(full);
                },
                "width": "10%"
            },
            {
                "targets": 2,
                "data": null,
                "render": function(full){
                    return renderDatum(full);
                },
                "width": "15%"
            },
            {
                "targets": 3,
                "data": null,
                "render": function(full){
                    return renderAction(full);
                },
                "orderable": false,
                "searchable": false,
                "width": "10%"
            }
        ],
        order:[[1, "desc"]],
        pageLength: 50

    });

And bc i have seen similar Problems where the Source-Problem was in StartUp:

        public void ConfigureServices(IServiceCollection services)
    {
        services.AddDbContext<TestDbcontext>(options => options.UseSqlServer(Configuration.GetConnectionString("TestDB"),
            sqlServerOptionsAction: sqlOptions =>
            {
                sqlOptions.EnableRetryOnFailure(
                maxRetryCount: 10,
                maxRetryDelay: TimeSpan.FromMinutes(5),
                errorNumbersToAdd: null
                );
            }));

        if (Env.IsDevelopment())
        {
            UseFakeAuthenticationAndAuthorization(services);

            //UseAuthenticationAndAuthorization(services, Configuration);
        }
        else
        {
            //UseFakeAuthenticationAndAuthorization(services);

            UseAuthenticationAndAuthorization(services, Configuration);
        }



        services.AddControllersWithViews();

        RepositoriesTestGUI(services);
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler("/Home/Error");
            // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
            app.UseHsts();
        }
        app.UseHttpsRedirection();
        app.UseStaticFiles();

        app.UseRouting();

        app.UseAuthentication();
        app.UseAuthorization();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllerRoute(
                name: "default",
                pattern: "{controller=Home}/{action=Home}/{id?}");
        });
    }

Has someone else an Idea what could be the Problem? An API-Call is an absolute Necessity since the Storage contains 70k Files

EDIT:

By Request here are the Network Details

NetworkDetails

Bc this is my first Post i can't put embedded Pictures in apparently

Answer 1

The root cause of this problem is not having permission to access. The easiest way to test is to change the access level to Container.

My test steps:

Access a picture in container( Blob or Container access level ).

Uri like:

https://testaccount.blob.core.windows.net/testblob/SignalR.png

Result

Access a picture in container( private access level ). We will reproduce the issue.

Suggestion

We can write a method to generate sas token to access the files. You can refer my code or read the official doc.