How to enable docker support ASP.NET applications in Visual Studio

Introduction

In this article, you will know that how to enable docker support for ASP.NET application in Visual Studio. We will create an ASP.NET Core application docker support and also enable docker support in an existing application.

Prerequisites

• Docker for Windows
• Visual Studio 2017 or later with the .NET Core cross-platform development workload

Enable Docker support in a new application

You can get Docker support in your project when you create a Visual Studio web project, either. NET Core or the full framework. If you choose the .NET Core framework, you get the option to add Docker support in the new project wizard but for the full framework, we can add Docker support later context menu “Solution Explorer”. See below steps to create a .NET Core project with Linux container support:

Docker tools in Visual Studio understand the difference between. NET Core and the. NET full framework so the generated files will nicely reflect those different targeted platforms.

To add Docker support for the full framework, go through previous post - Containerizing a .NET application

Enable Docker support in a new application

You add Docker support after creating a project is by right-clicking the project in the “Solution Explorer” and then select “Docker Support” option under the Add submenu.

Visual Studio will add DockerFile and .dockerignore to the project that will be used to build a docker container image starts with a reference to the base image dotnet:2.2-aspnetcore-runtime.

Note: To build this container, you need to switch the Docker tools for Windows on your machine to run Linux containers. If it is targeting to different operating system type, then you would get errors during the build since you can't mix Linux containers with Windows containers.

Docker support also added the generated YAML files. YAML files can be used together with docker-compose to execute Docker commands to a set of containers instead of only one at a time so that multiple container can work together for the microservices scenarios.

docker build -f "D:\DevWorkSpaces\GitHub\WebDevLearning\WebDev\WebDev.Containerized.MVCWeb\Dockerfile" -t webdevcontainerizedmvcweb:dev

Build Docker image from CLI

Open command prompt in administrative mode and run the below command  in project folder:

C:\Users\niranjansingh\Source\Repos\WebDevLearning\WebDev\WebDev.AspNETMVC>docker build .

Running application under Docker Environment

For .NET Core framework applications, Just run the application by selecting the Docker option just after the Run arrow button. After that application will build and create Docker image according to the settings provided in the DockerFile.

For my case application is targeting “Linux” and Docker for Windows on my system is configured to run the Windows contains so it will not build my case. So, remember to switch particular target Operating system containers before you build the application.

For a .NET framework application, make docker-compose as startup project. After this modify the .yml files to build and run the contains.

You will see Docker Compose button on the place of “Docker” in .NET full framework applications.

Click on Debug button to let the docker decompose to build and run the docker image on the bases of yml file configuration.

How to use Angular Lifecycle hooks

A component has a lifecycle which is managed by Angular. Below are the Angular component life cycle hooks:

1. Create
2. Render
3. Create/Render child components
4. Process Changes
5. Destroy

Angular creates the component then renders it. After that it get the creates and renders its child components. If there are any changes in component’s data bound properties then processes changes and at last destroys it before removing its template from the DOM.
Angular provides a set of lifecycle hooks and below are few of them:

1. OnInit – it is used to perform component initialization and it is used to perform any component initialization after Angular has initialized the data bound properties. It is a good place to retrieve the data for the template from a back-end service.
2. OnChanges - It is used to perform any action after Angular sets data bound input properties.
3. OnDestroy – This lifecycle hook to perform any clean-up before Angular destroys the component.

Using Angular Lifecycle Hooks

To use a lifecycle hook, you have to follow the below steps:

Implement the lifecycle hook interface

Angular provides several interfaces you can implement, including one interface for each lifecycle hook. For example, the interface for the OnInit lifecycle hook is OnInit.

export ProductListComponent implements OnInit {

Import Lifecycle hook from Angular packages

You have to import the lifecycle hook interface. Include OnInit in the import statement with Component as below

import { Component, OnInit } from '@angular/core';

Implement lifecycle hook method

After that you have to implement lifecycle hook method. Lifecycle hook interface defines one method which has name prefixed with ng with interface name. For example, the OnInit interface hook method is named ngOnInit.

ngOnInit() { // Some code here } 

Complete component declaration:

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'pm-products',
  templateUrl: './product-list.component.html',
  styleUrls:['./product-list.component.css']
})
export class ProductListComponent implements
{
       constructor() { }
      ngOnInit() { }
}

In this you can use another Angular Lifecycle hooks to implement required functionality at particular event.