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Adding multiple health check endpoint for dotnet core application

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Imagine the scenario when we need to expose one health check endpoint for checking application liveliness and another endpoint for checking application readiness. Lets assume, liveliness endpoint is responsible to see if the application is healthy and ready to receive traffic. On the other hand, readiness endpoint is responsible to check if the application is responsive, if not - the application will be restarted by some way to fix that. We can use the Health Checks provided by  ASP.NET Core  to achieve this with filtering by tags. Lets assume that we have a "/ping" endpoint in our application that responses with "pong". We can add a health check to hit the ping endpoint to see if our application is responsive or not. I am also assuming that the application relies on ElasticSearch for processing API requests. So, I am adding another health check for ElasticSearch. Now we need to register those health checks: And here is the implementation of ...
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Microsoft.IdentityModel.Protocols.OpenIdConnectProtocolInvalidNonceException

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I was using openId connect authentication with IdentityServer (v4) in a recent project and my client application was throwing following error: Microsoft.IdentityModel.Protocols.OpenIdConnectProtocolInvalidNonceException: IDX10311: RequireNonce is 'true' (default) but validationContext.Nonce is null. A nonce cannot be validated. If you don't need to check the nonce, set OpenIdConnectProtocolValidator.RequireNonce to 'false'. at Microsoft.IdentityModel.Protocols.OpenIdConnectProtocolValidator.ValidateNonce(JwtSecurityToken jwt, OpenIdConnectProtocolValidationContext validationContext) in c:\workspace\WilsonForDotNet45Release\src\Microsoft.IdentityModel.Protocol.Extensions\OpenIdConnectProtocolValidator.cs:line 332 at Microsoft.IdentityModel.Protocols.OpenIdConnectProtocolValidator.Validate(JwtSecurityToken jwt, OpenIdConnectProtocolValidationContext validationContext) in c:\workspace\WilsonForDotNet45Release\src\Microsoft.IdentityModel.Protocol.Extensions\OpenIdCo...
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Beginning .NET Core development with docker for windows

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Step 1: Open up visual studio and add your .Net Core app. Here, I have created an MVC application on .NET Core 2.0. Also I have Docker for Windows (Community Edition) installed in my machine. Step 2: Add a file named "Dockerfile" or any custom name of your preference to the project directory. Below is sample content of the docker file to build docker image of a simple MVC app. More details about Docker commands:  https://docs.docker.com/engine/reference/builder/ . Step 3: Add docker support to the app from Project menu. It will add a new docker-compose project to the solution. Set the new project as startup project for debugging. Here is a snapshot of how it should look like: Step 4: Update the contents of docker-compose.yml and docker-compose.override.yml. Below are sample contents from the example app (dockerfile command can be skipped if default filename is used). More details about docker compos...
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Adding security headers to prevent XSS and MiTM attacks in .Net Core

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As a developer, we need to consider security when designing and building web applications. HTTP Response Headers allow server to pass additional information to instruct browsers how to handle sensitive data and content of the application and/or from external or untrusted sources. HTTP response security headers provide an extra layer of protection to help mitigating vulnerabilities and attacks. One way to add those security headers from .Net Core application is by writing a custom action filter that would be executed before serving any response from the application. Below is a example of the custom attribute: To apply this globally for all responses, we can add this to the Startup class as in below: To apply trusted source for any particular action: And here is the outcome: HAPPY CODING   👌
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TypeScript - keeping compiled files in a separate directory

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When we use TypeScripts in visual studio projects, the compiled JavaScript (.js) files generated from the TypeScripts (.ts) are saved by default in the same directory where the ts files are located. Sometimes it could be annoying for example: if we want to ignore the compiled js files from source control. We can separate the directory for the compiled files very easily with a simple project setting. Lets say we have a folder structure in a visual studio solution as in below: As you can see, we have different folders for different modules inside our script folder and I've added the "js" folder to put all the compiled javascript files inside it so that I can ignore them from source control. To do this, I've changed the "TypeScript Build" settings (using Visual Studio 2015) from the project properties dialog: Notice that I've checked to redirect the JavaScript output to a directory. If you don't want to generate mapping files, you should u...
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Creating transformations for custom config files

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Visual Studio provides native support to add application config transforms. But it is restricted to the native configuration files only. Also by default it only provides transforms for debug and release environment. If you need to use your own custom configuration file for custom defined environment, below are two options you can follow: Option 1: Do it "manually" Let's assume, we have a configuration file: Configuration.xml in a project. We want to add Configuration.Staging.xml and Configuration.Production.xml as transforms. To achieve this, I can add those xml files manually first and then edit the project file (.csproj) as below and then re-load the project: <ItemGroup>     <Content Include =" Configuration.xml " >        <SubType> Designer </SubType>        <TransformOnBuild> true </TransformOnBuild>        ...
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System.TypeAccessException: Named type "CustomGrainState" is invalid: Type string "CustomGrainState" cannot be resolved.

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Sometimes Orleans throws the following exception when it fails to serialize a custom object: System.TypeAccessException: Named type "Simple.GrainImplementation.CustomGrainState" is invalid: Type string "Simple.GrainImplementation.CustomGrainState" cannot be resolved. at Orleans.Serialization.BinaryTokenStreamReader.ReadSpecifiedTypeHeader() at Orleans.Serialization.SerializationManager.DeserializeInner(Type expected, BinaryTokenStreamReader stream) at Orleans.Serialization.BuiltInTypes.DeserializeOrleansResponse(Type expected, BinaryTokenStreamReader stream) at Orleans.Serialization.SerializationManager.DeserializeInner(Type expected, BinaryTokenStreamReader stream) at Orleans.Serialization.SerializationManager.Deserialize(Type t, BinaryTokenStreamReader stream) at Orleans.Serialization.SerializationManager.Deserialize(BinaryTokenStreamReader stream) at Orleans.Runtime.Message.DeserializeBody(List`1 bytes) at Orleans.Runtime.Message.get_B...
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