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Articles and tutorials on .NET Core, ASP.NET MVC, Kendo UI, Windows 10, Windows Mobile, Orchard

  • Creating a Kubernetes cluster using Azure Container Serivce and Cloud Shell

    Azure Container Service(ACS) is a service offering from Microsoft in Azure which helps you to create, configure and manage a cluster of VM's for hosting your containerized applications. It has got support for orchestrators such as DC/OS, Docker Swarm, and Kubernetes. There are a lot of ways in which you can set up ACS in Azure like setting it up directly from the Portal itself or using Azure CLI from your local machine etc. But in this post, I will be using the Azure Cloud Shell to set up the service and the orchestrator will be Kubernetes.

    All the steps shown in this post is executed from the Azure Cloud Shell, it's an online terminal available in the Azure portal itself and can be invoked by clicking on the icon in the top right corner in the portal. Since  Azure CLI and Kuberbetes is installed in the shell by default we can straight away go and execute the commands used in the post

    Step 1

    Whatever resource we creates in Azure like Web Apps, Virtual Machines, IP Addresses, Virtual Machines, Blob storage etc needs to be associated with a resource group. A resource group acts as a container that holds all the resources used by the solution in Azure and it is recommended to keep all the resources that are related to your solution in a single resource group.

    Let's create a resource group first in Azure using the following command

    az group create --name aksgroup --location eastus

    This command will create a new group with name aksgroup in the data center located in East US region


  • How to a create a private Docker registry in Azure

    The containerization technology has been around for some years, but it only came to the forefront when a company called Docker released their toolset which is also called Docker. Just like what shipping containers did to the logistics industry, docker revolutionized the way which we shipped software. Along with the tooling, they also created a public registry called Docker Hub to store the images created using the toolset. It's free and open to all, but in some case such as enterprises building their own proprietary software doesn't want to keep it in a public domain. So to avoid this Docker supports private registries also and it can reside in on-premises servers or in the cloud. In this post, I am going to show how can we create a private registry in Azure, Microsoft's cloud platform and then to use it for pushing and pulling images from it.

    Pre-Requisites

    1. An Azure Subscription
    2. Somewhat familiarity in Azure
    3. Beginner level knowledge in using Docker

    I have already written an article about creating an image and a container based on it using Docker, please feel free to refer it if want to get a quick refresher.

    Setup

    In this post, I will be using the Azure Cloud Shell which is available on the portal to run all the commands. If you are hearing it for the first time, please refer the official documentation here. It basically gives a browser-based shell experience and supports both Bash and PowerShell. You can also the portal or Azure CLI for the same.

    First of all, we will check what all subscriptions are available for you and will set one as default if you have more than one using the following commands

    To list the available subscriptions,

    az account list

    and to set one as default

    az account set --subscription <subscription id or name>

    Creating Azure Container Registry

    Whenever you provision anything in Azure, it will create a set of assets, for example in the case of a VM it will create storage, virtual networks, availability sets etc. It will hold all these assets in a container which is called the Resource Groups, which helps to monitor, control all the assets from a single location. So for our private registry, let's create a new resource group using the following command

    az group create --name BlogSampleResGroup  --location eastasia

    This will create a resource group named BlogSamplesResGroup in East Asia region

    To create the registry, we will use

    az acr create --name BlogSampleResRegsitry  --resource-group BlogSampleResGroup  --sku Basic

    The value in the name parameter will be the name of our registry and will be created in the BlogSamplesResGroup. Azure Container Registry have 3 tiers which provide different pricing and other options. Those are Basic, Standard, and Premium. Please refer the documentation for more details. That's all we need to do for setting up the registry and if you go to the portal now, you can see the newly created registry.

    Pushing Image to the Repository.

    So we have the private repository up and running, now we let's push an image to the repository. For this I will be making use of the hello-world image available in the Docker Hub. I will pull that image down to my local machine using the docker pull command.

    docker pull hello-world

    If you execute the docker images command. it will be shown on the list. To create a container in the local machine using this image, use the below command

    docker run -it hello-world

    The output of the command will be as shown in the image below.

    So, we have verified that the image is good and we can create a container using it. Now let's push that image to our private registry. Before that, I will use the docker tag command to tag the name of the repository that matches our registry name

    docker tag hello-world blogsampleresregsitry.azurecr.io/blog/hello-world

    Before you push the image, the first thing you will need to do is to log in to our registry. For that, you will need to execute the docker login command and the parameters such as repository name, username and password are needed and you can get it from the Azure portal itself. You can find this information under Access Keys in Settings.

    To upload the image to the repository, use the docker push command

    docker push blogsampleresregsitry.azurecr.io/blog/hello-world

    If you now go to the Repositories in the Registry, you will see our newly pushed image there.


  • Hosting a ASP.NET Core application in a Docker container using microsoft/aspnetcore image

    You all will be familiar with Docker by now given its popularity among developers and infra people and some of you may have already created containers using Docker images. One of the most widely used workflows among people using .NET Core will create a new web application by using the dotnet new command as shown below.

    The below example uses ASP.NET Core 2.0 framework, in which the dotnet new command will create the project as well as restores the dependencies specified in the csproj file by default. I have already written a post about it and you can refer it for information about it

    Then you will do a build to see if there are any errors and use dotnet run command which will self-host the web application


  • What's changed with new command in .NET Core 2.0

    Microsoft has released a major revision to the .NET Core framework around mid of August bumping the version to 2.0. This release includes not only the upgrade to the core framework but also include ASP.NET Core 2.0 and Entity Framework 2.0. Also along with this .NET Standard 2.0 is also released and it's now supporting around 32K + APIs and is a huge leap from what we had until now. You can read more about it by going to the announcement here.

    One of the changes among these is that the dotnet restore is now an implicit command which means that there is no need to execute the restore command explicitly for commands which needed to do a restore before executing it. 

    For example in .NET Core 1.1 whenever we executed a dotnet new command for creating a project we needed to execute the restore command before doing a build or execution. With .NET Core 2.0 when we execute the new command, the restore is now run automatically as part of the tooling. The following are the list of the commands which have got implicit support for restoration.

    new
    run
    build
    publish
    pack
    test

  • Getting Started with Angular Development Using Cloud9 Online IDE

    Cloud 9 is an online IDE hosted in the cloud and runs inside the browser. It's built on top of a Linux container and offers most of the features found in a standalone IDE. To start using it, one needs to create an account at Cloud 9 website. Once you created the account, you will be able to create workspaces as per your development needs. Given below is the screenshot of the IDE which I created for web development.

    For using Cloud9 or c9 in short for all your development needs, you will need to create a workspace based on the Blank template as shown below

     


  • Generate C# Classes from a JSON String Easily Using Visual Studio

    As developers, we are often faced with certain tasks that are very repetitive in nature, which can also be time consuming to solve it. For example, whenever we need to reserialize a complex JSON string to classes we may need to write a lot of code. Until recently, whenever I needed to do such task I invariably create the classes manually and if it's a complex string, I was spending way too much time on that.

    When the instances like these began to happen every now and then, I decided to search for online options which can spit out classes from a JSON string. After some googling, I found out this site json2csharp.com which can do what I was looking for. You only need to paste the JSON in the input box and click on the Generate button to get the classes in C#.


  • Bug : dotnet CLI Template Engine Produces Invalid Code if Name of the Directory is a Valid C# Keyword

    With the release of .NET Core 1.0 tooling, dotnet new make use of the templating engine to generate various types of projects like Console App, Web App, WebAPI etc. If you are not aware of it, please read my earlier post on it here.


  • Stream Video Using Azure Media Services

    Recently I faced some dilemma in setting up video streaming for a site which I was working on. Since most of the targeted audience was from the enterprises, I wanted to avoid YouTube and other popular streaming services because of the greater possibility of it getting blocked by the corporate firewalls. So after some research, I found that the offering from Microsoft Azure very interesting and decided to explore it further. So in this post, I will be going through the various steps for setting up video streaming using Azure Media Services.

    From the documentation, Azure Media Service is

    An extensible cloud-based platform that enables developers to build scalable media management and delivery applications. Media Services is based on REST APIs that enable you to securely upload, store, encode and package video or audio content for both on-demand and live streaming delivery to various clients (for example, TV, PC, and mobile devices).

    Setting Up Media Services

    To get started, search for Media Services by typing it in the search box and then click on the first one under Web + Mobile category

    When you click on the Create button, you will be prompted to give a Name, choose a subscription, resource group, location and a storage account. Make sure that you choose the same region for your location and storage account, otherwise you may face problems down the line.

    We are now all set for creating a media service, just click on the Create button to start the deployment and you will see a new entry under Media Services after the deployment as shown below.


  • Executing a Task in the Background in ASP.NET MVC

    In some cases we want to execute some long running task in the background without affecting the main thread. One classic example is sending mails when we are implementing a sign in module. Mostly people will either go for a scheduled job independent of the application or do it in the main thread itself. 

    .NET Framework 4.5.2 has got a new API called QueueBackgroundWorkItem which can execute short-lived resource intense tasks in an effective and reliable manner. As per the documentation

    QBWI schedules a task which can run in the background, independent of any request. This differs from a normal ThreadPool work item in that ASP.NET automatically keeps track of how many work items registered through this API are currently running, and the ASP.NET runtime will try to delay AppDomain shutdown until these work items have finished executing.

    One of the advantages of using the QBWI(QueueBackgroundWorkItem) is that it can keep track of the items that are registered through this API is currently running and the runtime will be able to delay the shutdown of the App Domain upto 90 seconds so that the running tasks can be completed. 

    Let's see an example of file upload in ASP.NET MVC. In this example, I will chose file from the local machine using the file upload control and when you click the Upload button, the file will be saved inside a folder in the server which will be handled by the QBWI. 

    View 

    @{
        ViewBag.Title = "Index";
    }
    @model List<string>
    
    <h2>Index</h2>
    @using (Html.BeginForm("UploadFile", "Home", FormMethod.Post, new { id = "frmImageGallery", enctype = "multipart/form-data" }))
     { 
       <input type="file" name="file" />
       <input type="submit" value="Upload"  id="btnUpload" />
     }
    
    <h2>Images</h2>
    @foreach (var item in Model)
    { 
        <p><img src="@String.Concat("Images/Uploaded/",item)" style="height:200px" /></p><br />
    }
    <script>
        $(function () {
            $(document).on("click", "#btnUpload", function (event) {
                event.preventDefault();
                var fileOptions = {
                    success: res,
                    dataType: "json"
                }
                $("#frmImageGallery").ajaxSubmit(fileOptions);
            });
    
        }); 
    </script>
    
    

  • Add/Remove References Using dotnet CLI Tool

    In the latest update made to the .NET Core tooling, dotnet new and add command has undergone significant changes in the usage and options available for the command. You can read more about the updates here in the official blog. In this current update it replaces the dotnet add p2p command with a new syntax.

    Adding a Reference

    Syntax

    dotnet add reference <path to project file>

    Usage 

    dotnet add reference ..\Lib\Lib.csproj

    When you execute the following command it will get added to the project and if look at the csproj file of the project to which the reference is added you will see the entry for it

    Remove a Reference

    Syntax

    dotnet remove reference <path to the proj file which needs to be removed>

    Usage

    dotnet remove reference ..\Lib\Lib.csproj

    To remove the referernce we will use the dotnet remove reference as shown below.