Overview:

Azure App Service on Linux provides pre-defined application stacks on Linux with support for languages such as .NET, PHP, Node.js and others. You can also use a custom Docker image to run your web app on an application stack that isn’t already defined in Azure.

This post shows you how to deploy an image from an Azure Container Registry (ACR) to App Service.

Below are the Azure services available for Containers.

Demo: Run a custom container in Azure App Service

Prerequisites

• An Azure account
• Docker
• Visual Studio Code
• The Azure App Service extension for VS Code. You can use this extension to create, manage, and deploy Linux Web Apps on the Azure Platform as a Service (PaaS).
• The Docker extension for VS Code. You can use this extension to simplify the management of local Docker images and commands and to deploy built app images to Azure.
• Understanding Container concepts: Refer below Posts
• Rehost an on-premises application to Containers
• App Modernization using AKS (Azure Kubernetes Services)

Steps (Summary):

1 – Create a container registry

2 – Sign in, VSC and verify Docker Images

3 – Check prerequisites (docker version)

4 – Create and build image; to simply starts that app

5 – Deploy to container registry

6 – Deploy to App Service

The App Service app pulls from the container registry every time it starts. If you rebuild your image, you just need to push it to your container registry, and the app pulls in the updated image when it restarts.

To tell your app to pull in the updated image immediately, restart it.

Step-by-step

1 – Create a container registry

Create either from Azure Portal.

And validate in VSC.

Command/CLI

2 – Sign in, VSC and verify Docker Images 

 3 – Check prerequisites (docker version)

 4 – Create and build image; to simply starts that app;

 5 – Deploy to container registry;

<acr-name>.azurecr.io/<image-name>/<tag>

mycintainerregistryrk.azurecr.io/dockerfile/1.0

Executing task:

docker build –pull –rm -f “dockerfile.dockerfile” -t

mycintainerregistryrk.azurecr.io/dockerfile/1.0 “.”

6 – Deploy to App Service;

The App Service app pulls from the container registry every time it starts. If you rebuild your image, you just need to push it to your container registry, and the app pulls in the updated image when it restarts. To tell your app to pull in the updated image immediately, restart it.

Validate

Code behind:

Understanding Dockerfile

Containerize an app with Docker tutorial – .NET | Microsoft Learn

FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build-env 
WORKDIR /App 
# Copy everything 
COPY . ./ 
# Restore as distinct layers 
RUN dotnet restore # Build and publish a release 
RUN dotnet publish -c Release -o out # Build runtime image 
FROM mcr.microsoft.com/dotnet/aspnet:8.0 
WORKDIR /App 
COPY --from=build-env /App/out .
 ENTRYPOINT ["dotnet", "DotNet.Docker.dll"]

Conclusion

Containerizing .NET applications using Docker provides numerous benefits, including portability, scalability, and an immutable infrastructure. By following the steps outlined in this post, you can easily deploy your .NET apps in custom containers on Azure App Service or locally using Docker.

Whether you are developing or deploying .NET applications, containerization offers a flexible and powerful solution for managing and scaling your applications.

Happy coding! 🚀🐳

References:

https://learn.microsoft.com/en-us/azure/app-service/quickstart-custom-container?tabs=dotnet&pivots=container-linux-vscode
https://learn.microsoft.com/en-us/dotnet/core/docker/build-container?tabs=windows&pivots=dotnet-8-0