@duycs

Create a ASP.NET Core project then deploy to Heroku server via CircleCI continuous integration

Criteria

Help you choose a solution modern, cross-platform, automation to build your project
For small-scale applications, everything is free, so good for study and make a demo
Your application can access online, you will feel realistic and can share your ideas

Source

https://github.com/duycs/demo-netcore

Keywords

ASP.NET Core
Docker container
Platform as a Service
Heroku
Continuous integration
CircleCI

Before starting, you learn a little bit about concepts with these keywords. If you don’t know it yet, please read some reference articles and discuss with friends

ASP.NET Core: is a cross-platform, high-performance, open-source framework for building modern, cloud-based, Internet-connected applications.
https://docs.microsoft.com/en-us/aspnet/core/?view=aspnetcore-2.2
Docker container: is a platform for developers and sysadmins to build, share, and run applications with containers. The use of containers to deploy applications is called containerization.
https://docs.docker.com/get-started/
Platform as a Service: that provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app.
https://en.wikipedia.org/wiki/Platform_as_a_service
Heroku: is a container-based cloud Platform as a Service (PaaS). Developers use Heroku (as a server/hosting) to deploy, manage, and scale modern apps.
https://www.heroku.com/about
Continuous integration (CI): is a practice that encourages developers to integrate their code into a master branch of a shared repository early and often.
CircleCI: is a platform enables engineering teams with automation and continuous integration. CircleCI automates your software builds, tests, and deployments.
https://circleci.com/docs/2.0/about-circleci/#section=welcome

Now, when you already know about the concepts, you will use Heroku to host and run your ASP.NET Core application via CircleCI continuous integration:

You will have Docker pack the web application inside of the container, and then use CircleCI to deploy the Docker container to Heroku Container Registry.

Setup your local development

1. ASP.NET Core running on .NET Core

This demo is version 2.2, but you can use latest version.
Download installers of SDK and Runtimes compatible with your operating system: https://dotnet.microsoft.com/download/dotnet-core/2.2

2. Docker container

Download docker desktop compatible with your operating system:
https://docs.docker.com/docker-for-windows/install/
https://docs.docker.com/docker-for-mac/install/

3. Your project idea

Do you have any ideas?
Let’s do it to leaning and creativily!

Steps

1. You can get directly by using Fork the complete code of this article on GitHub to become your project that will be deployed:

https://github.com/duycs/demo-netcore

2. If don’t fork the article’s project, you can create your project

2.1 Create new project ASP.NET Core

Create a new folder for your project.
At the folder, open Command/Terminal then run this command to create a template webapi project:
```
dotnet new webapi
```
The project’s name is named as folder name, you can use Visual-Studio-Code tool to open the folder then start development.

2.2 Dockerize ASP.NET Core application

To dockerize your application, you need to create new Dockerfile in your project folder.
Here is a complete Dockerfile looks like:

# Grab an image with a small OS image made for .Net Core
FROM microsoft/dotnet:2.2-sdk AS build-env
# Working directory is /app
WORKDIR /app

# Copy csproj and restore as distinct layers
COPY *.csproj ./
RUN dotnet restore

# Copy everything else and build
COPY . ./
RUN dotnet publish -c Release -o out

# Build runtime image
FROM microsoft/dotnet:2.2-aspnetcore-runtime
WORKDIR /app
COPY --from=build-env /app/out .

# ENTRYPOINT ["dotnet", "demo-net-core.dll"]
# heroku uses the following
CMD ASPNETCORE_URLS=http://*:$PORT dotnet demo-net-core.dll

At this article, project name is “demo-net-core”, so you should change this name to your project name at Dockerfile

2.3 Config CI/CD pipeline

Create a folder .circleci in the root folder of your repository.
Create a new file named config.yml inside that folder.
Here is a complete config.yml looks like:

version: 2
jobs:
 build:
   machine: true
   steps:
     - checkout 

     # build image
     - run: |         
         docker info
         docker build -t aspnetapp -f Dockerfile .
     # deploy the image
     - run: |         
         docker login --username=$HEROKU_USERNAME --password=$HEROKU_API_KEY registry.heroku.com
         docker tag aspnetapp registry.heroku.com/$HEROKU_APP_NAME/web
         docker push registry.heroku.com/$HEROKU_APP_NAME/web                
         curl https://cli-assets.heroku.com/install.sh | sh
         heroku container:release web -a $HEROKU_APP_NAME

3. Create your Heroku application

Log in to Heroku or Sign up to create a new account if you don’t have one: https://id.heroku.com/login
After that, create a new app, choose the name for your application and select the desired region.
Save the name for later, we will use it with CircleCI.

4. Set up your project on CircleCI with Heroku

Login to CircleCI with your Github: https://circleci.com/vcs-authorize/
Then grant authorization your Github Repository for CircleCI
On CircleCI dashboard, click ADD-PROJECTS, chooe your project which you want to deploy on Heroku, click Set-Up-Project.
At Set up project, choose Operating System is Linux then click Start-building

After that is done, you will need to set up environment variables for your CircleCI project at Setting:

HEROKU_API_KEY: You can find your Heroku API key in your Heroku Account settings
HEROKU_USERNAME: Your username should be your email that you use to sign in
HEROKU_APP_NAME: The name that you used when you were creating new Heroku application.

5. Coding and push to master branch, you will see Continuous-integration

Coding and push to master branch, after a few minutes, go to your Heroku application domain and enjoy your change!
The article’s app can be found at: https://duycs-demo-net-core.herokuapp.com

References

https://circleci.com/docs/2.0/configuration-reference/
https://devcenter.heroku.com/categories/reference
https://developer.okta.com/blog/2019/09/18/build-a-simple-dotnet-core-app-in-docker
https://softchris.github.io/pages/dotnet-dockerize.html#build-our-image-start-container
https://codingblast.com/hosting-asp-net-core-on-heroku-with-dockercircleci-for-free/