Blog - kimserey lam

Sep 07, 2018

Polly Httpclient Resilience In Dotnet

Few weeks ago I explained [how to use the new HttpClientFactory. This freed ourselves from managing the confusing lifecycle of a HttpClient and at the same time allowed us to setup commmon options like base address for all HttpClient injections in our classes. Today we will see how we can setup timeout and retry policies for the HttpClient in in ASP NET Core using Polly.

Aug 31, 2018

Infrastructure Continuous Deployment

Few weeks ago we saw how we could Setup continious integration and deployment to deploy an application using Gitlab Pipeline. We configured a service with systemd and had an ASP NET Core application automatically deployed when code was pushed to the repository. This automation allows us to reduce interaction with the server and reducing the manual work. The “infrastructure” configurations like systemd service files and nginx site files must also be created or edited on the server therefore it makes sense to also have them automatically deployed. On top of that, it makes even more sense to have them save in repository and source controlled. Today we will see how we can leverage Gitlab Pipeline to setup a continuous deployment for our infrastructure files.

Aug 24, 2018

Nginx Debugging With Mitmproxy

In previous blog posts, we saw how to proxy requests to an ASP NET Core application using Nginx. We saw that request headers also can be proxied with proxy_set_header In order to ease development, we need to be able to debug the values to verify that they are what we expect. Today we will see two methods to inspect the proxied requests.

Aug 17, 2018

Sdk Projects And Assets Json

Last week I encountered an issue with MSBuild while trying to run it from command line. The issue did not appear when using VisualStudio right click + build but only appeared when using msbuild.exe CLI directly with a clean project.

Aug 10, 2018

Aspnetcore 2.1 Apicontroller

ASP NET Core 2.1 brings a set a enhacements for Web API development, Web API being a service accessible via HTTP and returning result in Json format. Those enhancements aim to simplify the composition of those APIs and also remove unecessary functionalities. Today we will explore those enhancements.

Aug 03, 2018

Update Npm Packages With Ncu

Frontend libraries progress very rapidly. After just one month, a project can see all its packages needing an upgrade. Today we will see how we can figure which packages need to be updated and how to do it.

Jul 27, 2018

Angular With Signalr Core

Last week we saw how to configure SignalR and get a server notifying a client built as Razor page via Websockets. We completed the post by having a fully functional backend setup with SignalR and authentication done via Resource Owner Password. Today we will see how we can connect to SignalR hub from an Angular application and demonstrate how we can authenticate.

Jul 24, 2018

Manage Aspnetcore Configuration With Systemd

Managing configurations can be challenging. We cannot simply check-in in our repository secrets and connection strings and at the same time we want an easy way to maintain them. Today we will see how we can manage secrets is am easy way on Ubuntu with systemd.

Jul 22, 2018

Debug 502 Bad Gateway Nginx

When proxying a request to an underlying server, it is necessary to validate its SSL certificate. For example, if we have a process running on https://localhost:5001, we can configure Nginx to validate the certificate used by localhost:5001. But if we miss one step, we face the common error 502 Bad Gateway returned by Nginx. Today we will see two scenarios where we can face the error and how to fix them.

Jul 20, 2018

End To End Encryption Between Nginx Aspnetcore Kestrel Angular

Internet is moving toward secure connections whereby HTTPS is a priority. Browsers are now warning users when navigating to non secured website. With this movement, Kestrel and ASPNET Core have adopted the mentality of security by default rather than security when needed. HTTPS will now be the default and HTTP will be a necessity due to implementation constraints. Together with Lets Encrypt and ACME protocol, we do not have excuses for not implementing an SSL connection.

Jul 16, 2018

Httpclientfactory Aspnetcore

ASP.NET Core 2.1 ships with a factory for HttpClient called HttpclientFactory. This factory allows us to no longer care about the lifecycle of the HttpClient by leaving it to the framework. Today we will see few ways of instantiating clients.

Jul 13, 2018

Signalr Aspnetcore

SignalR is a framework from ASP NET Core allowing us to establish a two way communication between client and server. This two way communication allows the client to send messages to the server but more importantly allows the server to push messages to the client. SignalR makes use of Websocket when available else it falls back to SSE or pulling. Today we will focus on how to setup SignalR to work with WSS, Websocket secure and how we can authenticate the user requesting to connect to our SignalR hub via Websocket.

Jul 08, 2018