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European ASP.NET Core Hosting :: How to Use Serilog with ASP.NET Core 2

clock August 7, 2019 08:48 by author Scott

Today, I will discuss about Serilog. What is Serilog? Serilog is an open source event library for .NET. Serilog gives you two important components: loggers and sinks (outputs). Most applications will have a single static logger and several sinks, so in this example I’ll use two: the console and a rolling file sink.

Starting with a new ASP.NET Core 2.0 Web Application running on .NET Framework (as in the image to the right), begin by grabbing a few packages off NuGet:

  • Serilog
  • Serilog.AspNetCore
  • Serilog.Settings.Configuration
  • Serilog.Sinks.Console
  • Serilog.Sinks.RollingFile

Next, you will need to modify some files.


Startup constructor

Create the static Log.Logger by reading from the configuration (see appsettings.json below). The constructor should now look like this:

public Startup(IConfiguration configuration)
   Log.Logger = new LoggerConfiguration().ReadFrom.Configuration(configuration).CreateLogger();
Configuration = configuration;

BuildWebHost method

Next, add the .UseSerilog() extension to the BuildWebHost method. It should now look like this:

public static IWebHost BuildWebHost(string[] args) =>
.UseSerilog() // <-- Add this line

The BuildWebHost method might look strange because the body of this method is called an expression body rather than a traditional method with a statement body.

Configure method

At the start of the configure method, add one line at the top to enable the Serilog middleware. You can optionally remove the other loggers as this point as well. Your Configure method should start like this:

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
     loggerFactory.AddSerilog(); // <-- Add this line


At the root level of the appsettings.json (or one of the environment-specific settings files), add something like this:

"Serilog": {
     "Using": [ "Serilog.Sinks.Console" ],
     "MinimumLevel": "Debug",
     "WriteTo": [
            { "Name": "Console" },
                    "Name": "RollingFile",
                    "Args": {
                          "pathFormat": "logs\\log-{Date}.txt",
                          "outputTemplate": "{Timestamp:yyyy-MM-dd HH:mm:ss.fff zzz} [{Level}] {Message}{NewLine}{Exception}"
     "Enrich": [ "FromLogContext", "WithMachineName", "WithThreadId" ],
     "Properties": {
     "Application": "My Application"

If you’re wondering about the pathFormat and what other parameters you can use, there aren’t that many. {Date} is the only “switch” you can use with this particular sink. But you can use any environment variable (things like %TEMP%), allowing for a pathFormat of:


The outputTemplate has a LOT of options that I won’t get into here because the official documentation does a great job of explaining it.

As for the event levels, I’ve copied the list below from the official documentation for reference.

  1. Verbose – tracing information and debugging minutiae; generally only switched on in unusual situations
  2. Debug – internal control flow and diagnostic state dumps to facilitate pinpointing of recognised problems
  3. Information – events of interest or that have relevance to outside observers; the default enabled minimum logging level
  4. Warning – indicators of possible issues or service/functionality degradation
  5. Error – indicating a failure within the application or connected system
  6. Fatal – critical errors causing complete failure of the application

You’ll also notice in the above JSON that the “Using” property is set to an array containing “Serilog.Sinks.Console” but not “Serilog.Sinks.RollingFile”. Everything appears to work, so I am not sure what impact this property has.  

European ASP.NET Core Hosting :: How to Fix “An error occurred while starting the application” in ASP.NET Core on IIS

clock July 5, 2019 07:33 by author Scott

.NET Core is the latest Microsoft product and Microsoft always keep update their technologies. We have written tutorial about how to publish ASP.NET Core on IIS server, but we know that some of you sometimes receive error when deploying your ASP.NET Core. Feel frustrated to fix the issue? Yeah, not only you have headache, but some of our clients also experience same problem like you. That’s why we write this tutorial and hope it can help to fix your issue!

Anyone see this error? Have problem to solve it? We want to help you here!

The Problem


It basically means something bad happened with your application. Things you need to check

  • You might not have the correct .NET Core version installed on the server.
  • You might be missing DLL’s
  • Something went wrong in your Program.cs or Startup.cs before any exception handling kicked in

If you use Windows Server, then I believe that you can’t find anything on your Event Viewer too. You’ll notice that there is no error on your Event Viewer log. Why? This is because Event Logging must be wired up explicitly and you’ll need to use the Microsoft.Extensions.Logging.EventLog package, and depending on the error, you might not have a chance to even catch it to log to the Event Viewer.

How to Fix it?

So, how to fix error above? The followings are the steps to fix the error:

1. Open your web.config

2. Change stdoutLogEnabled=true

3. Create a logs folder

  • Unfortunately, the AspNetCoreModule doesn’t create the folder for you by default
  • If you forget to create the logs folder, an error will be logged to the Event Viewer that says: Warning: Could not create stdoutLogFile \\?\YourPath\logs\stdout_timestamp.log, ErrorCode = -2147024893.
  • The “stdout” part of  the value “.\logs\stdout” actually references the filename not the folder.  Which is a bit confusing.

4. Run your request again, then open the \logs\stdout_*.log file

Note – you will want to turn this off after you’re done troubleshooting, as it is a performance hit.

So your web.config’s aspNetCore element should look something like this

 <aspNetCore processPath=”.\YourProjectName.exe” stdoutLogEnabled=”true” stdoutLogFile=”.\logs\stdout” />

Doing this will log all the requests out to this file and when the exception occurs, it will give you the full stack trace of what happened in the \logs\stdout_*.log file




Hope this helps!

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European ASP.NET Core Hosting :: How to Host ASP.NET Core Application as a Windows Service

clock July 4, 2019 08:38 by author Scott

I recently came across the need to host a .NET Core web app as a Windows Service. In this case, it was because each machine needed to locally be running an API. But it’s actually pretty common to have a web interface to manage an application on a PC without needing to set up IIS. For example if you install a build/release management tool such as Jenkins or TeamCity, it has a web interface to manage the builds and this is able to be done without the need for installing and configuring an additional web server on the machine.

Luckily .NET Core actually has some really good tools for accomplishing all of this (And even some really awesome stuff for being able to run a .NET Core web server by double clicking an EXE if that’s your thing).

A Standalone .NET Core Website/Web Server

The first step actually has nothing to do with Windows Services. If you think about it, all a Windows Service is, is a managed application that’s hidden in the background, will restart on a machine reboot, and if required, will also restart on erroring. That’s it! So realistically what we first want to do is build a .NET Core webserver that can be run like an application, and then later on we can work out the services part.

For the purpose of this tutorial, I’m just going to be using the default template for an Core website. The one that looks like this:

We first need to head to the csproj file of our project and add in a specific runtime (Or multiple), and an output type. So overall my csproj file ends up looking like:

<Project Sdk="Microsoft.NET.Sdk.Web">

    <PackageReference Include="Microsoft.AspNetCore.App" />

Our RuntimeIdentifiers (And importantly notice the “s” on the end there) specifies the runtimes our application can be built for. In my case I’m building only for Windows 10, but you could specify other runtime monkiers if required.

Ontop of this, we specify that we want an outputtype of exe, this is so we can have a nice complete exe to run rather than using the “dotnet run” command to start our application. I’m not 100% sure, but the exe output that comes out of this I think is simply a wrapper to boot up the actual application dll. I noticed this because when you change code and recompile, the exe doesn’t change at all, but the dll does.

Now we need to be able to publish the app as a standalone application. Why standalone? Because then it means any target machine doesn’t have to have the .NET Core runtime installed to get everything running. Ontop of that, there is no “what version do you have installed?” type talk. It’s just double click and run.

To publish a .NET Core app as standalone, you need to run the following command from the project directory in a command prompt/powershell:

dotnet publish --configuration Release --self-contained -r win10-x64

It should be rather self explanatory. We are doing a publish, using the release configuration, we pass through the self contained flag, and we pass through that the runtime we are building for is Windows 10 – 64 Bit.

From your project directory, you can head to:  \bin\Release\netcoreapp2.1\win10-x64\publish

This contains your application exe as well as all framework DLL’s to run without the need for a runtime to be installed on the machine. It’s important to note that you should be inside the Publish folder. One level up is also an exe but this is not standalone and relies on the runtime being installed.

From your publish folder, try double clicking yourapplication.exe.

Hosting environment: Production
Content root path: \bin\Release\netcoreapp2.1\win10-x64\publish
Now listening on:
Now listening on: https://localhost:5001
Application started. Press Ctrl+C to shut down.

In your browser head to http://localhost:5000 and you now have your website running from an executable. You can copy and paste this publish folder onto any Windows 10 machine, even a fresh install, and have it spin up a webserver hosting your website. Pretty impressive!

Installing As A Window Service

So the next part of this tutorial is actually kinda straight forward. Now that you have an executable that hosts your website, installing it as a service is exactly the same as setting up any regular application as a service. But we will try and have some niceties to go along with it.

First we need to do a couple of code changes for our app to run both as a service, and still be OK running as an executable (Both for debugging purposes, and in case we want to run in a console window and not as a service).

We need to install the following from your package manager console:

Install-Package Microsoft.AspNetCore.Hosting.WindowsServices

Next we need to go into our program.exe and make your main method look like the following:

public static void Main(string[] args)
 var isService = !(Debugger.IsAttached || args.Contains("--console"));
 var builder = CreateWebHostBuilder(args.Where(arg => arg != "--console").ToArray()); 

 if (isService)

 var pathToExe = Process.GetCurrentProcess().MainModule.FileName;
 var pathToContentRoot = Path.GetDirectoryName(pathToExe);

 var host = builder.Build(); 

 if (isService)

This does a couple of things :

  • It checks whether we are using the debugger, or if we have a console argument of “–console” passed in.
  • If neither of the above are true, it sets the content root manually back to where the exe is running. This is specifically for the service runtime.
  • Next if we are a service, we use a special “RunAsService()” method that .NET Core gives us
  • Otherwise we just do a “Run()” as normal.

Obviously the main point of this is that if the debugger is attached (e.g. we are running from visual studio), or we run from a command prompt with the flag “–console”, it’s going to run exactly the same as before. Back in the day we used to have to run the service with a 10 second sleep at the start of the app, and quickly try and attach the debugger to the process before it kicked off to be able to set breakpoints etc. Now it’s just so much easier.

Now let’s actually get this thing installed!

In your project in Visual Studio (Or your favourite editor) add a file called install.bat to your project. The contents of this file should be:

sc create MyService binPath= %~dp0MyService.exe
sc failure MyService actions= restart/60000/restart/60000/""/60000 reset= 86400
sc start MyService
sc config MyService start=auto

Obviously replace MyService with the name of your service, and be sure to rename the exe to the actual name of your applications exe. Leave the %~dp0 part as this refers to the current batch path (Allowing you to just double click the batch file when you want to install).

The install file creates the service, sets up failure restarts (Although these won’t really be needed), starts the service, and sets the service to auto start in the future if the machine reboots for any reason.

Go ahead and create an uninstall.bat file in your project. This should look like:

sc stop MyService
timeout /t 5 /nobreak > NUL
sc delete MyService

Why the timeout? I sometimes found that it took a while to stop the service, and so giving it a little bit of a break inbetween stopping and deleting helped it along it’s way.

Important! For both of these files, be sure to set them up so they copy to the output directory in Visual Studio. Without this, your bat files won’t output to your publish directory.

Go ahead and publish your application again using our command from earlier:

dotnet publish --configuration Release --self-contained -r win10-x64

Now in your publish directory, you will find your install and uninstall bat files. You will need to run both of these as Administrator for them to work as installing Windows Services requires elevated access. A good idea is that the first time you run these, you run them from a command prompt so you can catch any errors that happen.

Once installed, you should be able to browse to http://localhost:5000 and see your website running silently in the background. And again, the best part is when you restart your machine, it starts automatically. Perfect!

European ASP.NET Core Hosting :: Integration Test ASP.NET Core

clock June 25, 2019 09:19 by author Scott

Writing integration tests for ASP.NET Core controller actions used for file uploads is not a rare need. It is fully supported by ASP.NET Core integration tests system. This post shows how to write integration tests for single and multiple file uploads.

Getting started

Suppose we have controller action for file upload that supports multiple files. It uses complex composite command for image file analysis and saving. Command is injected to action by framework-level dependency injection using controller action injection.

[Authorize(Roles = "Admin")]
public async Task<IActionResult> Upload(IList<IFormFile> files, int? parentFolderId,
                                        [FromServices]SavePhotoCommand savePhotoCommand)
    foreach(var file in files)
        var model = new PhotoEditModel();
        model.FileName = Path.GetFileName(file.FileName);
        model.Thumbnail = Path.GetFileName(file.FileName);
        model.ParentFolderId = parentFolderId;
        model.File = file;
        await savePhotoCommand.Execute(model);
    ViewBag.Messages = savePhotoCommand.Messages;
    return View();

We want to write integration tests for this action but we need to upload at least one file to make sure that command doesn’t fail.

Making files available for integration tests

It’s good practice to have files for testing available no matter where tests are run. It’s specially true when writing code in team or using continuous integration server to run integration tests. If we don’t have many files and the files are not large then we can include those files in project.

Important thing is to specify in Visual Studio that these files are copied to output folder.

Same way it’s possible to use also other types of files and nobody stops us creating multiple folders or folder trees if we want to organize files better.

Uploading files in integration tests

Here is integration tests class for controller mentioned above. Right now there’s only one test and it is testing Upload action. Notice how image files are loaded from TestPhotos folder to file streams and how form data object is built using the file streams.

public class PhotosControllerTests : IClassFixture<WebApplicationFactory<Startup>>
    private readonly WebApplicationFactory<Startup> _factory;
    public PhotosControllerTests(WebApplicationFactory<Startup> factory)
        _factory = factory;
    public async Task Upload_SavesPhotoAndReturnSuccess()
        // Arrange
        var expectedContentType = "text/html; charset=utf-8";
        var url = "Photos/Upload";
        var options = new WebApplicationFactoryClientOptions { AllowAutoRedirect = false };
        var client = _factory.CreateClient(options);
        // Act
        HttpResponseMessage response;
        using (var file1 = File.OpenRead(@"TestPhotos\rt-n66u.jpg.webp"))
        using (var content1 = new StreamContent(file1))
        using (var file2 = File.OpenRead(@"TestPhotos\speedtest.png.webp"))
        using (var content2 = new StreamContent(file2))
        using (var formData = new MultipartFormDataContent())
            // Add file (file, field name, file name)
            formData.Add(content1, "files", "rt-n66u.jpg.webp");
            formData.Add(content2, "files", "speedtest.png.webp");
            response = await client.PostAsync(url, formData);
        // Assert
        var responseString = await response.Content.ReadAsStringAsync();
        Assert.Equal(expectedContentType, response.Content.Headers.ContentType.ToString());

For actions that accept only one file we need only one call to Add() method of formData.

Wrapping up

Integration tests mechanism in ASP.NET Core is flexible enough to support also more advanced scenarios like file uploads in tests. It’s not very straightforward and we can’t just call few methods of HTTP client to do it but it’s still easy enough once we know the tricks. If we keep test files in integration tests project then we don’t have to worry about getting files to machine where integration tests are running.

European ASP.NET Core Hosting - :: Javascript, CSS, HTML in ASP.NET Core

clock April 12, 2019 09:45 by author Scott

This article will teach you how to include and customize the use of static files in ASP .NET Core web applications. It is not a tutorial on front-end web development.

If your ASP .NET Core web app has a front end – whether it’s a collection of MVC Views or a Single-Page Application (SPA) – you will need to include static files in your application. This includes (but is not limited to): JavaScript, CSS, HTML and various image files.

When you create a new web app using one of the built-in templates (MVC or Razor Pages), you should see a “wwwroot” folder in the Solution Explorer. This points to a physical folder in your file system that contains the same files seen from Visual Studio. However, this location can be configured, you can have multiple locations with static files, and you can enable/disable static files in your application if desired. In fact, you have to “opt in” to static files in your middleware pipeline.

Configuring Static Files via Middleware

Let’s start by observing the Startup.cs configuration file. We’ve seen this file several times throughout this blog series. In the Configure() method, you’ll find the familiar method call to enable the use of static files.

public void Configure(IApplicationBuilder app, IHostingEnvironment env)

This call to app.UseStaticFiles() ensures that static files can be served from the designated location, e.g. wwwroot.

It’s useful to note the placement of this line of code. It appears before app.UseMvc(), which is very important. This ensures that static file requests can be processed and sent back to the web browser without having to touch the MVC middleware. This becomes even more important when authentication is used.

In the code below, you can see the familiar call to app.UseStaticFiles() once again. However, there is also a call to app.UseAuthentication(). It’s important for the authentication call to appear after the call to use static files. This ensure that the authentication process isn’t triggered when it isn’t needed.

public void Configure(IApplicationBuilder app, IHostingEnvironment env)

By using the middleware pipeline in this way, you can “short-circuit” the pipeline when a request has been fulfilled by a specific middleware layer. If a static file has been successfully served using the Static Files middleware, it prevents the next layers of middleware (i.e. authentication, MVC) from processing the request.

Customizing Locations for Static Files

It may be convenient to have the default web templates create a location for your static files and also enable the use of those static files. As you’ve already seen, enabling static files isn’t magic. Removing the call to app.useStaticFiles() will disable static files from being served. In fact, the location for static files isn’t magic either.

public class Program
   public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>

Behind the scenes, this method call sets the “content root” to the current directory, which contains the “wwwroot” folder, your project’s “web root”. These can both be customized.



You may also use the call to app.UseStaticFiles() to customize an alternate location to serve static files. This allows you to serve additional static files from a location outside of the designated web root.

using Microsoft.Extensions.FileProviders;
using System.IO;
public void Configure(IApplicationBuilder app)
   app.UseStaticFiles(new StaticFileOptions
      FileProvider = new PhysicalFileProvider
         Path.Combine(env.ContentRootPath, "AltStaticRoot")),
         RequestPath = "/AltStaticFiles"

Wait a minute… why does it look like there are two alternate locations for static files? There is a simple explanation:

  • In the call to Path.Combine(), the “AltStaticRoot” is an actual folder in your current directory. This Path class and its Combine() method are available in the System.IO namespace.
  • The “AltStaticFiles” value for RequestPath is used as a root-level “virtual folder” from which images can be served. The PhysicalFileProvider class is available in the Microsoft.Extensions.FileProviders namespace.

The following markup may be used in a .cshtml file to refer to an image, e.g. MyImage01.png:

<img src="~/AltStaticFiles/MyImages/MyImage01.png" />

The screenshot below shows an example of an image loaded from an alternate location.

The screenshot below shows a web browser displaying such an image.

Preserving CDN Integrity

When you use a CDN (Content Delivery Network) to serve common CSS and JS files, you need to ensure that the integrity of the source code is reliable. You can rest assured that ASP .NET Core has already solved this problem for you in its built-in templates.

<environment include="Development">
 <link rel="stylesheet" href="~/lib/bootstrap/dist/css/bootstrap.css" />

<environment exclude="Development">

Right away, you’ll notice that there are two conditional <environment> blocks in the above markup. The first block is used only during development, in which the bootstrap CSS file is obtained from your local copy. When not in development (e.g. staging, production, etc), the bootstrap CSS file is obtained from a CDN, e.g. CloudFlare.

You could use an automated hash-generation tool to generate the SRI (Subresource Integrity) hash values, but you would have to manually copy the value into your code. You can try out the relatively-new LibMan (aka Library Manager) for easily adding and updating your client-side libraries.

LibMan (aka Library Manager)

The easiest way to use LibMan is to use the built-in features available in Visual Studio. Using LibMan using the IDE is as easy as launching it from Solution Explorer. Specify the provider from the library you want, and any specific files you want from that library.

In the popup that appears, select/enter the following:

  • Provider: choose from cdnjs, filesystem, unpkg
  • Library search term, e.g. @aspnet/signalr@1… pick latest stable if desired
  • Files: At a minimum, choose specific files, e.g. signalr.js and/or its minified equivalent


For more on LibMan (using VS or CLI), check out the official docs:

Use LibMan with ASP.NET Core in Visual Studio:

Use the LibMan command-line interface (CLI):

Library Manager: Client-side content manager for web apps:

In any case, using LibMan will auto-populate a “libman.json” manifest file, which you can also inspect and edit manually.

  "version": "1.0",
  "defaultProvider": "unpkg",
  "libraries": [
      "library": "@aspnet/signalr@1.1.0",
      "destination": "wwwroot/lib/signalr/",
      "files": [

What About NPM or WebPack?

If you’ve gotten this far, you may be wondering: “hey, what about NPM or WebPack?”

It’s good to be aware that LibMan is a not a replacement for your existing package management systems. In fact, the Single-Page Application templates in Visual Studio (for Angular and React) currently use npm and WebPack. LibMan simply provides a lightweight mechanism to include client-side libraries from external location.


European ASP.NET Core Hosting :: How to Use Auth Cookies in ASP.NET Core

clock March 29, 2019 11:49 by author Scott

Cookie-based authentication is the popular choice to secure customer facing web apps. For .NET programmers, ASP.NET Core has a good approach that is worth looking into. In this take, I will delve deep into the auth cookie using ASP.NET Core 2.1. Version 2.1 is the latest LTS version as of the time of this writing. So, feel free to follow along, I’ll assume you’re on Visual Studio or have enough C# chops to use a text editor. I will omit namespaces and using statements to keep code samples focused. If you get stuck, download the sample code found at the end.

With ASP.NET 2.1, you can use cookie-based authentication out of the box. There is no need for additional NuGet packages. New projects include a metapackage that has everything, which is Microsoft.AspNetCore.App. To follow along, type dotnet new mvc in a CLI or do File > New Projectin Visual Studio.

For those of you who come from classic .NET, you may be aware of the OWIN auth cookie. You will be happy to know those same skills transfer over to ASP.NET Core quite well. The two implementations remain somewhat similar. With ASP.NET Core, you still configure the auth cookie, set up middleware, and set identity claims.


To begin, I’ll assume you know enough about the ASP.NET MVC framework to gut the scaffolding into a skeleton web app. You need a HomeController with an Index, Login, Logout, and Revoke action methods. Login will redirect to Index after it signs you in, so it doesn’t need a view. I’ll omit showing view sample code since views are not the focus here. If you get lost, be sure to download the entire demo to play with it.

I’ll use debug logs to show critical events inside the cookie authentication. Be sure to enable debug logs in appsettings.json and disable Microsoft and system logs.

My log setup looks like this:

"LogLevel": {
  "Default": "Debug",
  "System": "Warning",
  "Microsoft": "Warning"

Now you’re ready to build a basic app with cookie authentication. I’ll forgo HTML forms with a user name and password input fields. These front-end concerns only add clutter to what is more important which is the auth cookie. Starting with a skeleton app shows how effective it is to add an auth cookie from scratch. The app will sign you in automatically and land on an Index page with an auth cookie. Then, you can log out or revoke user access. I want you to pay attention to what happens to the auth cookie as I put authentication in place.

Cookie Options

Begin by configuring auth cookie options through middleware inside the Startup class. Cookie options tell the authentication middleware how the cookie behaves in the browser. There are many options, but I will only focus on those that affect cookie security the most.

  • HttpOnly: A flag that says the cookie is only available to servers. The browser only sends the cookie but cannot access it through JavaScript.
  • SecurePolicy: This limits the cookie to HTTPS. I recommend setting this to Always in prod. Leave it set to None in local.
  • SameSite: Indicates whether the browser can use the cookie with cross-site requests. For OAuth authentication, set this to Lax. I am setting this to Strict because the auth cookie is only for a single site. Setting this to None does not set a cookie header value.

There are cookie options for both the auth cookie and a global cookie policy. Stay alert since the cookie policy can override auth cookie options and vice versa. Setting HttpOnly to false in the auth cookie will override cookie policy options. While setting SameSite in the cookie policy overrides auth cookie options. In my demo, I’ll illustrate both scenarios, so it is crystal clear how this works.

In the Startup class, find the ConfigureServices method and type:

  .AddCookie(options =>
    options.Cookie.HttpOnly = true;
    options.Cookie.SecurePolicy = _environment.IsDevelopment()
      ? CookieSecurePolicy.None : CookieSecurePolicy.Always;
      options.Cookie.SameSite = SameSiteMode.Lax;

This creates the middleware service with the AddAuthentication and AddCookie methods. AuthenticationScheme is useful when there is more than one auth cookie. Many instances of the cookie authentication let you protect endpoints with many schemes. You supply any string value; the default is set to Cookies. Note that the options object is an instance of the CookieAuthenticationOptions class.

The SecurePolicy is set through a ternary operator that comes from _environment. This is a private property that gets set in the Startup constructor. Add IHostingEnvironment as a parameter and let dependency injection do the rest.

In this same ConfigureServices method, add the global cookie policy through middleware:

services.Configure<CookiePolicyOptions>(options =>
  options.MinimumSameSitePolicy = SameSiteMode.Strict;
  options.HttpOnly = HttpOnlyPolicy.None;
  options.Secure = _environment.IsDevelopment()
    ? CookieSecurePolicy.None : CookieSecurePolicy.Always;

Take a good look at SameSite and HttpOnly settings for both cookie options. When I set the auth cookie, you will see this set to HttpOnly and Strict. This illustrates how both options override each other.

Invoke this middleware inside the request pipeline in the Configure method:


The cookie policy middleware is order sensitive. This means it only affects components after invocation. By invoking the authentication middleware, you will get a HttpContext.User property. Be sure to call this UseAuthentication method before calling UseMvc.


In the HomeController add an AllowAnonymous filter to the Login and Logout methods. There are only two action methods available without an auth cookie.

Inside the Startup class, look for the AddMvc extension method and add a global auth filter:

services.AddMvc(options => options.Filters.Add(new AuthorizeFilter()))

With the app secure, configure the cookie name and login / logout paths. Find where the rest of the CookieAuthenticationOptions are and do:

options.Cookie.Name = "SimpleTalk.AuthCookieAspNetCore";
options.LoginPath = "/Home/Login";
options.LogoutPath = "/Home/Logout";

This will cause the app to redirect to the login endpoint to sign in. However, before you can take this for a spin, you’ll need to create the auth cookie.

Do this inside the Login action method in the HomeController:

var claims = new List<Claim>
  new Claim(ClaimTypes.Name, Guid.NewGuid().ToString())

var claimsIdentity = new ClaimsIdentity(
  claims, CookieAuthenticationDefaults.AuthenticationScheme);
var authProperties = new AuthenticationProperties(); 

await HttpContext.SignInAsync(
  new ClaimsPrincipal(claimsIdentity),

AuthenticationProperties drive further auth cookie behavior in the browser. For example, the IsPersistent property persists the cookie across browser sessions. Be sure to get explicit user consent when you enable this property. ExpiresUtc sets an absolute expiration, be sure to enable IsPersistent and set it to true. The default values will give you a session cookie that goes away when you close the tab or browser window. I find the default values in this object enough for most use cases.

To take this for a spin load up the browser by going to the home or Index page. Note it redirects to Login which redirects back to Index with an auth cookie.

Once this loads it looks something like this. Be sure to take a good look at how the auth cookie is set:

JWT Identity Claim

Often, an auth cookie isn’t enough to secure API endpoints or microservices. For the web app to call a service, it can use a JWT bearer token to authenticate. To make the access token accessible, place it inside the identity claims.

In the Login action method within HomeController, expand the list of claims with a JWT:

var userId = Guid.NewGuid().ToString();
var claims = new List<Claim>
  new Claim(ClaimTypes.Name, userId),
  new Claim("access_token", GetAccessToken(userId))

private static string GetAccessToken(string userId)
  const string issuer = "localhost";
  const string audience = "localhost"; 

  var identity = new ClaimsIdentity(new List<Claim>
    new Claim("sub", userId)

  var bytes = Encoding.UTF8.GetBytes(userId);
  var key = new SymmetricSecurityKey(bytes);
  var signingCredentials = new SigningCredentials(
    key, SecurityAlgorithms.HmacSha256); 

  var now = DateTime.UtcNow;
  var handler = new JwtSecurityTokenHandler(); 

  var token = handler.CreateJwtSecurityToken(
    issuer, audience, identity,
    now, now.Add(TimeSpan.FromHours(1)),
    now, signingCredentials); 

  return handler.WriteToken(token);

I must caution, don’t ever do this is in production. Here, I use the user id as the signing key which is symmetric to keep it simple. In a prod environment use an asymmetric signing key with public and private keys. Client apps will then use a well-known configuration endpoint to validate the JWT.

Placing the JWT in ClaimsIdentity makes it accessible through the HttpContex.User property. For this app, say you want to put the JWT in a debug log to show off this fancy access token.

In the Startup class, create this middleware inside the Configure method:

app.Use(async (context, next) =>
  var principal = context.User as ClaimsPrincipal;
  var accessToken = principal?.Claims
    .FirstOrDefault(c => c.Type == "access_token"); 

  if (accessToken != null)

  await next();

The _logger is another private property you set through the constructor. Add ILogger<Startup> as a parameter and let dependency injection do the rest. Note the ClaimsPrincipal has a list of Claims you can iterate through. What I find useful is to look for a Type of claim like an access_token and get a Value. Because this is middleware always call next() so it doesn’t block the request pipeline.


To log out of the web app and clear the auth cookie do:

await HttpContext.SignOutAsync(

This belongs inside the Logout action method in the HomeController. Note that you specify the authentication scheme. This tells the sign-out method which auth cookie it needs to blot out. Inspecting HTTP response headers reveals Cache-Control and Pragma headers set to no-cache. This shows the auth cookie disables browser caching when it wants to update the cookie. The Login action method responds with the same HTTP headers.


There are use cases where the app needs to react to back-end user access changes. The auth cookie will secure the application, but, remains valid for the lifetime of the cookie. With a valid cookie, the end-user will not see any changes until they log out or the cookie expires. In ASP.NET Core 2.1, one way to validate changes is through cookie authentication events. The validation event can do back-end lookups from identity claims in the auth cookie. Create the event by extending CookieAuthenticationEvents. Override the ValidatePrincipal method and set the event in the auth cookie options.

For example:

public class RevokeAuthenticationEvents : CookieAuthenticationEvents
  private readonly IMemoryCache _cache;
  private readonly ILogger _logger; 

  public RevokeAuthenticationEvents(
    IMemoryCache cache,
    ILogger<RevokeAuthenticationEvents> logger)
    _cache = cache;
    _logger = logger;

  public override Task ValidatePrincipal(
    CookieValidatePrincipalContext context)
    var userId = context.Principal.Claims
      .First(c => c.Type == ClaimTypes.Name); 

    if (_cache.Get<bool>("revoke-" + userId.Value))

      _cache.Remove("revoke-" + userId.Value);
      _logger.LogDebug("Access has been revoked for: "
        + userId.Value + ".");

    return Task.CompletedTask;

To have IMemoryCache set by dependency injection, put AddMemoryCache inside the ConfigureSerices method in the Startup class. Calling RejectPrincipal has an immediate effect and kicks you back out to Login to get a new auth cookie. Note this relies on in-memory persistence which gets set in the Revoke action method. Keep in mind that this event runs once per every request, so you want to use an efficient caching strategy. Doing an expensive lookup at every request will affect performance.

Revoke access by setting the cache inside the Revoke method in the HomeController:

var principal = HttpContext.User as ClaimsPrincipal;
var userId = principal?.Claims
  .First(c => c.Type == ClaimTypes.Name); 

_cache.Set("revoke-" + userId.Value, true);
return View();

After visiting the Revoke endpoint, the change does not have an immediate effect. After revocation, navigating home will show the debug log and redirect to Login. Note that landing in the Index page again will have a brand new auth cookie.

To register this event, be sure to set the EventsType in the CookieAuthenticationOptions. You will need to provide a scoped service to register this RevokeAuthenticationEvents. Both are set inside the ConfigureServices method in the Startup class.

For example:

options.EventsType = typeof(RevokeAuthenticationEvents);

The CookieValidatePrincipalContext in ValidatePrincipal can do more than revocation if necessary. This context has ReplacePrincipal to update the principal, then renew the cookie by setting ShouldRenew to true.

Session Store

Setting a JWT in the claims to have a convenient way to access identity data works well. However, every identity claim you put in the principal ends up in the auth cookie. If you inspect the cookie, you will notice it doubles in size with an access token. As you add more claims in the principal the auth cookie gets bigger. You may hit HTTP header limits in a prod environment with many auth cookies. In IIS, the default max limit is set to 8KB-16KB depending on the version. You can increase the limit, but this means bigger payloads per request because of the cookies.

There are many ways to quell this problem, like a user session to keep all JWTs out of the auth cookie. If you have current code that accesses the identity through the principal, then this is not ideal. Moving identity data out of the principal is risky because it may lead to a complete rewrite.

One alternative is to use the SessionStore found in CookieAuthenticationOptions. OWIN, for example, has a similar property. Implement the ITicketStore interface and find a way to persist data in the back-end. Setting the SessionStore property defines a container to store the identity across requests. Only a session identifier gets sent to the browser in the auth cookie.

Say you want to use in-memory persistence instead of the auth cookie:

public class InMemoryTicketStore : ITicketStore
  private readonly IMemoryCache _cache; 

  public InMemoryTicketStore(IMemoryCache cache)
    _cache = cache;

  public Task RemoveAsync(string key)

    return Task.CompletedTask;

  public Task<AuthenticationTicket> RetrieveAsync(string key)
    var ticket = _cache.Get<AuthenticationTicket>(key); 

    return Task.FromResult(ticket);

  public Task RenewAsync(string key, AuthenticationTicket ticket)
    _cache.Set(key, ticket); 

    return Task.CompletedTask;

  public Task<string> StoreAsync(AuthenticationTicket ticket)
    var key = ticket.Principal.Claims
      .First(c => c.Type == ClaimTypes.Name).Value; 

    _cache.Set(key, ticket); 

    return Task.FromResult(key);

Set an instance of this class in SessionStore inside CookieAuthenticationOptions, these options are set in the ConfigureServices method in the Startup class. One caveat is getting an instance since it needs a provider from BuildServiceProvider. A temporary IoC container here feels hacky and pines after a better solution.

A better approach is to use the options pattern in ASP.NET Core. Post-configuration scenarios set or change options at startup. With this solution, you leverage dependency injection without reinventing the wheel.

To put in place this options pattern, implement IPostConfigureOptions<CookieAuthenticationOptions>:

public class ConfigureCookieAuthenticationOptions
  : IPostConfigureOptions<CookieAuthenticationOptions>
  private readonly ITicketStore _ticketStore; 

  public ConfigureCookieAuthenticationOptions(ITicketStore ticketStore)
    _ticketStore = ticketStore;

  public void PostConfigure(string name,
           CookieAuthenticationOptions options)
    options.SessionStore = _ticketStore;

To register both InMemoryTicketStore and ConfigureCookieAuthenticationOptions, place this in ConfigureServices:

services.AddTransient<ITicketStore, InMemoryTicketStore>();

Make sure you make this change in the Startup class. If you peek inside Configure<CookiePolicyOptions>, for example, and crack open the code. Note the pattern; configuration runs through a singleton object and a lambda expression. ASP.NET Core uses this same options pattern under the hood. Now, firing this up in the browser and inspecting the auth cookie will have a much smaller footprint.


Implementing an auth cookie is seamless in ASP.NET Core 2.1. You configure cookie options, invoke middleware, and set identity claims. Sign in and sign out methods work based on an authentication scheme. Auth cookie options allow the app to react to back-end events and set a session store. The auth cookie is flexible enough to work well with any enterprise solution. 

European ASP.NET Core Hosting :: Using Docker to Store ASP.NET Core Kestrel Certificates

clock March 22, 2019 08:48 by author Scott

When working with ASP.Net Core in Docker containers, it can be cumbersome to deal with certificates. While there is a documentation about setting certificate for dev environment, there’s no real guidance on how to make it work when deploying containers in a Swarm for example.
In this article we are going to see how to take advantage of Docker secrets to store ASP.Net Core Kestrel certificates in the context of Docker Swarm.

Hosting the service

First of all, we are going to create à Swarm service on our machine that use the sample Asp.Net Core app. The purpose of this article is to make SSL work in the container withoutchanging anything to an existing image.

docker service create --name mywebsite --publish published=8080,target=80,mode=host microsoft/dotnet-samples:aspnetapp

We are creating service mywebsite, publishing only one port 8080 bound to the port 80 in the container using the host mode and using the image microsoft/dotnet-samples:aspnetapp. Please note that you can use others configuration (for example expose port in routing mesh mode).

Preparing the certificate

We need a certificate. It can be created via an external certificate authority but here for the sake of the article, we are going to create a self signed certificate (of course, don’t use this in production). We are using Powershell for this task (you can skip this if you already have a pfx certificate signed by a real CA).

$cert = New-SelfSignedCertificate -DnsName "mywebsite" -CertStoreLocation "cert:\LocalMachine\My"
$password = ConvertTo-SecureString -String "mylittlesecret" -Force -AsPlainText
$cert | Export-PfxCertificate -FilePath c:\temp\mywebsite.pfx -Password $password

Once you have your pfx, we are goind to unprotect it from the password. It might be seem unsecure but when it will be added to the Docker secret store, it will be stored securedly. For this task I will use OpenSSL (not possible with Powerhsell as far as I know). OpenSSL is provided with Git for example.

& 'C:\Program Files\Git\mingw64\bin\openssl.exe' pkcs12 -in c:\temp\mywebsite.pfx -nodes -out c:\temp\mywebsite.pem -passin pass:mylittlesecret
& 'C:\Program Files\Git\mingw64\bin\openssl.exe' pkcs12 -export -in c:\temp\mywebsite.pem -out c:\temp\mywebsite.unprotected.pfx -passout pass:

Now that the pfx is un protected, we can add it to the docker store certificate and display it.

docker secret create kestrelcertificate c:\temp\mywebsite.unprotected.pfx

docker secret ls

ID                          NAME                 DRIVER              CREATED             UPDATED

iapy6rolt7po1mwm9aw6z0qc5   kestrelcertificate                       13 minutes ago      13 minutes ago

Our secret being in the store, you can delete (or store securely somewhere else your pfx).

Making it work

We can now update our service to take in account this secret. When adding a secret to a service, Docker will create a file in a specific directory containing the value of the secret. On Windows it’s c:\programdata\docker\secrets.

Let’s update our service and see what happened inside the container.

docker service update --secret-add kestrelcertificate mywebsite

docker exec 4b51e736ce65 cmd.exe /c dir c:\programdata\docker\secrets

 Volume in drive C has no label.
 Volume Serial Number is 3CBB-E577

 Directory of c:\programdata\docker\secrets

11/15/2018  10:38 PM    <DIR>          .
11/15/2018  10:38 PM    <DIR>          ..
11/15/2018  10:38 PM    <SYMLINK>      kestrelcertificate [C:\ProgramData\Docker\internal\secrets\iapy6rolt7po1mwm9aw6z0qc5]
               1 File(s)              0 bytes
               2 Dir(s)  21,245,009,920 bytes free

We can see that our secret exists and is named kestrelcertificate, as we named it in the command line.

We can therefore update our service to remove the old binding on port 80, replace it with a binding on port 443, tell Kestrel to use this port and finally give Kestrel the path of our secret.
This can be done with only one command:

docker service update --publish-rm published=8080,target=80,mode=host --publish-add published=8080,target=443,mode=host --env-add ASPNETCORE_URLS=https://+:443 --env-add Kestrel__Certificates__Default__Path=c:\programdata\docker\secrets\kestrelcertificate mywebsite

Wait a while that your service update, try to browse and it should work ! Well, actually it should only works on Linux.

Making it work on Windows

If you try to have a look a the logs generated by your service, you should end with something like this.

docker service logs mywebsite

mywebsite.1.uy3vm8txwxec@nmarchand-lt    | crit: Microsoft.AspNetCore.Server.Kestrel[0]
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |       Unable to start Kestrel.
mywebsite.1.uy3vm8txwxec@nmarchand-lt    | Internal.Cryptography.CryptoThrowHelper+WindowsCryptographicException: Unspecified error
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Internal.Cryptography.Pal.CertificatePal.FromBlobOrFile(Byte[] rawData, String fileName, SafePasswordHandle password, X509KeyStorageFlags keyStorageFlags)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at System.Security.Cryptography.X509Certificates.X509Certificate..ctor(String fileName, String password, X509KeyStorageFlags keyStorageFlags)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at System.Security.Cryptography.X509Certificates.X509Certificate2..ctor(String fileName, String password)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Server.Kestrel.KestrelConfigurationLoader.LoadCertificate(CertificateConfig certInfo, String endpointName)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Server.Kestrel.KestrelConfigurationLoader.LoadDefaultCert(ConfigurationReader configReader)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Server.Kestrel.KestrelConfigurationLoader.Load()
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer.ValidateOptions()
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer.StartAsync[TContext](IHttpApplication`1 application, CancellationToken cancellationToken)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |
mywebsite.1.uy3vm8txwxec@nmarchand-lt    | Unhandled Exception: Internal.Cryptography.CryptoThrowHelper+WindowsCryptographicException: Unspecified error
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Internal.Cryptography.Pal.CertificatePal.FromBlobOrFile(Byte[] rawData, String fileName, SafePasswordHandle password, X509KeyStorageFlags keyStorageFlags)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at System.Security.Cryptography.X509Certificates.X509Certificate..ctor(String fileName, String password, X509KeyStorageFlags keyStorageFlags)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at System.Security.Cryptography.X509Certificates.X509Certificate2..ctor(String fileName, String password)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Server.Kestrel.KestrelConfigurationLoader.LoadCertificate(CertificateConfig certInfo, String endpointName)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Server.Kestrel.KestrelConfigurationLoader.LoadDefaultCert(ConfigurationReader configReader)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Server.Kestrel.KestrelConfigurationLoader.Load()
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer.ValidateOptions()
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServer.StartAsync[TContext](IHttpApplication`1 application, CancellationToken cancellationToken)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Hosting.Internal.WebHost.StartAsync(CancellationToken cancellationToken)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Hosting.WebHostExtensions.RunAsync(IWebHost host, CancellationToken token, String shutdownMessage)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Hosting.WebHostExtensions.RunAsync(IWebHost host, CancellationToken token)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at Microsoft.AspNetCore.Hosting.WebHostExtensions.Run(IWebHost host)
mywebsite.1.uy3vm8txwxec@nmarchand-lt    |    at aspnetapp.Program.Main(String[] args) in C:\app\aspnetapp\Program.cs:line 18

We can see a nasty bug of Windows here (Github issue).
What did happen ? If you look closely at the dir command we made in the container, you’ll see that the secret is not really a file but instead a symbolic link to an other file. Unfortunately, Windows is unable to use a certificate that is a symlink. One solution could be to manually read the certificate with File.ReadAllBytes() and pass it to the constructor of X509Certificate. However, it would be against the purpose of this article which is to not modify the Docker image.

We can find a workaround by browsing the Docker documentation which states that the real file containing the secret (which in fact is the target of the symlink) can be found in the path c:\programdata\docker\internal\secrets\<secretid> where secretid is the id of the secret (as shown by docker secret ls).

We can update our service to change the path by updating the environment variable. It now works also on windows!

docker service update --env-rm
Kestrel__Certificates__Default__Path=c:\programdata\docker\secrets\kestrelcertificate --env-add Kestrel__Certificates__Default__Path=c:\programdata\docker\internal\secrets\iapy6rolt7po1mwm9aw6z0qc5 mywebsite

docker logs 7b54cdc42a86

Hosting environment: Production
Content root path: C:\app
Now listening on: https://[::]:443
Application started. Press Ctrl+C to shut down.

Final word

We have seen in this article how to use Docker secrets to store ASP.Net Core Kestrel certificates in our Docker Swarm. However, please keep in mind that the Windows workaround should be used with care as written in the Docker documentation.

Another word also about SSL Offloading : I know that usually the reverse proxy (Nginx, Traefik, etc.) is used to be the SSL termination but sometimes you still want SSL end to end. 

European ASP.NET Core Hosting :: ASP.NET Core with MySQL and Entity Framework Core

clock March 14, 2019 07:58 by author Scott

This article shows how to use MySQL with ASP.NET Core 2.1 using Entity Framework Core.

The Entity Framework MySQL package can be downloaded using the NuGet package Pomelo.EntityFrameworkCore.MySql. At present no official provider from MySQL exists for Entity Framework Core which can be used in an ASP.NET Core application.

The Pomelo.EntityFrameworkCore.MySql package can be added to the csproj file.

<Project Sdk="Microsoft.NET.Sdk"> 


    <ProjectReference Include="..\DomainModel\DomainModel.csproj" />

    <PackageReference Include="Microsoft.AspNetCore.App"  />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="2.2.0" PrivateAssets="All" />
    <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="2.0.1" />

    <Folder Include="Properties\" />


The web project which loads the project with EF Core needs to support migrations if you wish to create a database this way.

<Project Sdk="Microsoft.NET.Sdk.Web"> 


    <Content Update="wwwroot\**\*;Views;Areas\**\Views;appsettings.json;config.json;web.config">

    <ProjectReference Include="..\DataAccessMsSqlServerProvider\DataAccessMsSqlServerProvider.csproj" />
    <ProjectReference Include="..\DataAccessMySqlProvider\DataAccessMySqlProvider.csproj" />
    <ProjectReference Include="..\DataAccessPostgreSqlProvider\DataAccessPostgreSqlProvider.csproj"
    <ProjectReference Include="..\DataAccessSqliteProvider\DataAccessSqliteProvider.csproj" />
    <ProjectReference Include="..\DomainModel\DomainModel.csproj" />

    <PackageReference Include="Microsoft.AspNetCore.App"  />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="2.2.0" PrivateAssets="All" />
    <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.0" />
      <Folder Include="Migrations\" />

An EfCore DbContext can be added like any other context supported by Entity Framework Core.

using System;
using System.Linq;
using DomainModel.Model;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration; 

namespace DataAccessMySqlProvider
    // >dotnet ef migration add testMigration
    public class DomainModelMySqlContext : DbContext
        public DomainModelMySqlContext(DbContextOptions<DomainModelMySqlContext> options) :base(options)
        { }         

        public DbSet<DataEventRecord> DataEventRecords { get; set; } 

        public DbSet<SourceInfo> SourceInfos { get; set; } 

        protected override void OnModelCreating(ModelBuilder builder)
            builder.Entity<DataEventRecord>().HasKey(m => m.DataEventRecordId);
            builder.Entity<SourceInfo>().HasKey(m => m.SourceInfoId); 

            // shadow properties


        public override int SaveChanges()


            return base.SaveChanges();

        private void updateUpdatedProperty<T>() where T : class
            var modifiedSourceInfo =
                    .Where(e => e.State == EntityState.Added || e.State == EntityState.Modified); 

            foreach (var entry in modifiedSourceInfo)
                entry.Property("UpdatedTimestamp").CurrentValue = DateTime.UtcNow;

In an ASP.NET Core web application, the DbContext is added to the application in the startup class. In this example, the DbContext is defined in a different class library. The MigrationsAssembly needs to be defined, so that the migrations will work. If the context and the migrations are defined in the same assembly, this is not required.

public Startup(IHostingEnvironment env)
    var builder = new ConfigurationBuilder()
        .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
        .AddJsonFile("config.json", optional: true, reloadOnChange: true); 

    Configuration = builder.Build();
public void ConfigureServices(IServiceCollection services)
    var sqlConnectionString = Configuration.GetConnectionString("DataAccessMySqlProvider"); 

    services.AddDbContext<DomainModelMySqlContext>(options =>
            b => b.MigrationsAssembly("AspNetCoreMultipleProject")

The application uses the configuration from the config.json. This file is used to get the MySQL connection string, which is used in the Startup class.

    "ConnectionStrings": { 
        "DataAccessMySqlProvider": "server=localhost;userid=store;password=3333;database=store;"

MySQL workbench can be used to add the schema ‘store to the MySQL database. The user ‘store is also required, which must match the defined user in the connection string. If you configure the MySQL database differently, then you need to change the connection string in the config.json file.

Now the database migrations can be created and the database can be updated.

> dotnet ef migrations add mySqlMigration --context DomainModelMySqlContext
> dotnet ef database update --context DomainModelMySqlContext

If successful, the tables are created.

The MySQL provider can be used in a MVC controller using construction injection.

using System.Collections.Generic;
using DomainModel;
using DomainModel.Model;
using Microsoft.AspNetCore.Mvc;
using Newtonsoft.Json; 

namespace AspNet5MultipleProject.Controllers
    public class DataEventRecordsController : Controller
        private readonly IDataAccessProvider _dataAccessProvider; 

        public DataEventRecordsController(IDataAccessProvider dataAccessProvider)
            _dataAccessProvider = dataAccessProvider;

        public IEnumerable<DataEventRecord> Get()
            return _dataAccessProvider.GetDataEventRecords();

        public IEnumerable<SourceInfo> GetSourceInfos(bool withChildren)
            return _dataAccessProvider.GetSourceInfos(withChildren);

        public DataEventRecord Get(long id)
            return _dataAccessProvider.GetDataEventRecord(id);

        public void Post([FromBody]DataEventRecord value)

        public void Put(long id, [FromBody]DataEventRecord value)
            _dataAccessProvider.UpdateDataEventRecord(id, value);

        public void Delete(long id)

The controller api can be called using Fiddler:

POST http://localhost:5000/api/dataeventrecords HTTP/1.1
User-Agent: Fiddler
Host: localhost:5000
Content-Length: 135
Content-Type: application/json;  

  "Name":"Funny data",
    "Description":"second Source",

The data is added to the database as required.

European ASP.NET Core Hosting :: Smart Logging Middleware for ASP.NET Core

clock March 13, 2019 09:44 by author Scott

ASP.NET Core comes with request logging built-in. This is great for getting an app up-and-running, but the events are not as descriptive or efficient as hand-crafted request logging can be. Here is a typical trace from a single GET request to /about:

If the request fails because of an error, you'll see instead:

While these fine-grained events are sometimes useful, they take up storage space and bandwidth, and add noise to the log.

Spreading the information across many events also makes it harder to perform some analyses, for example, the HTTP method and elapsed time are on different events, making it hard to separate the timings of GET and POST requests to the same RequestPath.

In production we want:

One "infrastructure" event per normal request, with basic HTTP information attached

Extra information to help with debugging if a request fails due to a server-side (5xx) error

The same format and event type for all requests, so that logs from both successful and failed requests can be easily grouped, sorted and analyzed together

Here's the format we're aiming for, expanded so that you can see all of the attached properties:

Instead of five infrastructure events + one application event, just a single infrastructure event is logged. This makes the application's own "Hello" event much easier to spot.

This post includes the full source code for the middleware, so you can take it and modify it to include the information you find most useful.

Step 1: Install and Configure Serilog

ASP.NET Core includes some basic logging providers, but to get the most out of it you'll need to plug in a full logging framework like Serilog. If you haven't done that already, these instructions should have you up and running quickly.

Step 2: Turn off Information events from Microsoft and System

Where Serilog is configured, add level overrides for the Microsoft and System namespaces:

Log.Logger = new LoggerConfiguration() 
    .MinimumLevel.Override("Microsoft", LogEventLevel.Warning)
    .MinimumLevel.Override("System", LogEventLevel.Warning)
    // Other logger configuration

These can be turned back on for debugging when they're needed.

If you're using appsettings.json configuration, check out the level overrides example in the README.

Step 3: Add the SerilogMiddleware class

The SerilogMiddleware class hooks into the request processing pipeline to collect information about the requests:

using Microsoft.AspNetCore.Http; 
using Serilog; 
using Serilog.Events; 
using System; 
using System.Collections.Generic; 
using System.Diagnostics; 
using System.Linq; 
using System.Threading.Tasks;

namespace Datalust.SerilogMiddlewareExample.Diagnostics 
    class SerilogMiddleware
        const string MessageTemplate =
            "HTTP {RequestMethod} {RequestPath} responded {StatusCode} in {Elapsed:0.0000} ms";

        static readonly ILogger Log = Serilog.Log.ForContext<SerilogMiddleware>();

        readonly RequestDelegate _next;

        public SerilogMiddleware(RequestDelegate next)
            if (next == null) throw new ArgumentNullException(nameof(next));
            _next = next;

        public async Task Invoke(HttpContext httpContext)
            if (httpContext == null) throw new ArgumentNullException(nameof(httpContext));

            var sw = Stopwatch.StartNew();
                await _next(httpContext);

                var statusCode = httpContext.Response?.StatusCode;
                var level = statusCode > 499 ? LogEventLevel.Error : LogEventLevel.Information;

                var log = level == LogEventLevel.Error ? LogForErrorContext(httpContext) : Log;
                log.Write(level, MessageTemplate, httpContext.Request.Method, httpContext.Request.Path, statusCode, sw.Elapsed.TotalMilliseconds);
            // Never caught, because `LogException()` returns false.
            catch (Exception ex) when (LogException(httpContext, sw, ex)) { }

        static bool LogException(HttpContext httpContext, Stopwatch sw, Exception ex)

                .Error(ex, MessageTemplate, httpContext.Request.Method, httpContext.Request.Path, 500, sw.Elapsed.TotalMilliseconds);

            return false;

        static ILogger LogForErrorContext(HttpContext httpContext)
            var request = httpContext.Request;

            var result = Log
                .ForContext("RequestHeaders", request.Headers.ToDictionary(h => h.Key, h => h.Value.ToString()), destructureObjects: true)
                .ForContext("RequestHost", request.Host)
                .ForContext("RequestProtocol", request.Protocol);

            if (request.HasFormContentType)
                result = result.ForContext("RequestForm", request.Form.ToDictionary(v => v.Key, v => v.Value.ToString()));

            return result;

I've deliberately kept this to a single (somewhat ugly!) source file so that it's easy to copy, paste and modify.

There are a lot of design details and trade-offs involved. You can see that when a request is deemed to have failed, some additional information is attached, including the headers sent by the client, and the form data if any.

Step 4: Add the middleware to the pipeline

In your application's Startup.cs file, you can add the middleware either before or after the outermost exception handling components. If you add it before this, you won't get the full Exception information in any error events, but you will always be able to record the exact status code returned to the client. Adding the middleware into the pipeline inside the exception handling components (i.e., after them in the source code) will provide all exception detail but has to assume that the status code is 500 in this case.

public void Configure(IApplicationBuilder app, IHostingEnvironment env, 
                      ILoggerFactory loggerFactory)

    if (env.IsDevelopment())



    app.UseMvc(routes =>
            name: "default",
            template: "{controller=Home}/{action=Index}/{id?}");

Step 5: Profit!

Now you have a stream of request log events each with paths, status codes, timings, and exceptions:

We've seen how a simple customized logging strategy can not only produce cleaner events, but also reduce the volume of infrastructure log events.

ASP.NET Core Hosting :: How to Upload File using C# | SFTP Server

clock March 4, 2019 07:56 by author Scott

Although there are many Graphical Tools available for sending files to a server using SFTP. But as a developer, we may have a scenario where we need to upload a file to SFTP Serverfrom our Code.

A few days ago a job assigned to me was to develop a Task Scheduler for generating XML files daily on a specific time of the day & send these files on a Remote Server using File Transfer Protocol in a secure way.

In .Net Framework there are many Libraries available for uploading files to another machine using File Transfer Protocol but most of the libraries don’t work with .Net Core. In this Tutorial, we will develop a very simple SFTP client using C# for .Net Core.

Before start let’s have a quick look at SFTP.

What is SFTP?

SFTP stands for SSH File Transfer Protocol or Secure File Transfer Protocol. It is a protocol used to transfer files between remote machines over a secure shell.


In almost all cases, SFTP is preferable over FTP because of security features. FTP is not a secure protocol & it should only be used on a trusted network.

Choosing Library for C#

A lot of search & after testing many libraries I finally met with SSH.NET which was working perfectly with .Net Core 2.2 project & the good thing was that It does its job in a very few lines of Code.

So we’ll use SSH.NET

What is SSH.NET?

SSH.NET is an open-source library available at Nuget for .NET to work over SFTP. It is also optimized for parallelism to achieve the best possible performance. It was inspired by Sharp.SSH library which was ported from Java. This library is a complete rewrite using .Net, without any third party dependencies.

Here are the features of SSH.NET: 

Creating Project

I’m in love with VS Code right after its first release so I’m going to use VS Code for creating project to upload/transfer a file to a remote server using SFTP.

Create a console application using this command

dotnet new console

Installing SSH.NET

I won’t recommend you to install the latest version of SSH.NET. It has a bug, it can be stuck on transferring the file to the remote location.

version 2016.0.0 is perfect. 

run this command to install the library from NuGet

using package manager

Install-Package SSH.NET -Version 2016.0.0

or using .Net CLI

dotnet add package SSH.NET --version 2016.0.0


Finally, It’s time to create a class for SFTP Client Code.

Create a file with the name as “SendFileToServer” & add the below code

using Renci.SshNet

public static class SendFileToServer
// Enter your host name or IP here
private static string host = "";

// Enter your sftp username here
private static string username = "sftp";

// Enter your sftp password here
private static string password = "12345";
public static int Send(string fileName)
var connectionInfo = new ConnectionInfo(host, "sftp", new PasswordAuthenticationMethod(username, password));

// Upload File
using (var sftp = new SftpClient(connectionInfo)){

using (var uplfileStream = System.IO.File.OpenRead(fileName)){
sftp.UploadFile(uplfileStream, fileName, true);
return 0;

Now you can call this Method to transfer a file to SFTP Server like this


“myFile.txt” is the name of the file which should be located in your project root directory. 

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