How to Deploy ASP.NET Core App with Docker on Azure Web App

Deploying an ASP.NET Core application using Docker and Azure Web App for Containers is a modern and scalable approach for hosting cloud-native applications. This deployment strategy combines containerization with fully managed Azure infrastructure, enabling portability, consistency across environments, and simplified DevOps workflows. By packaging your application inside a Docker container and deploying it to Azure Web App for Containers, you gain flexibility, isolation, and production-ready scalability without managing virtual machines.

This article provides a complete practical guide, including architecture explanation, Dockerfile configuration, container registry setup, Azure deployment steps, real-world scenarios, advantages, disadvantages, and production best practices.

What Does It Mean to Deploy Using Docker and Azure Web App for Containers?

In traditional deployment, applications are published directly to a server. In containerized deployment:

• The ASP.NET Core application is packaged into a Docker image.

• The image contains application code, runtime, dependencies, and configuration.

• The image is pushed to a container registry.

• Azure Web App pulls and runs the container.

In simple terms, instead of deploying files, you deploy a portable runtime environment.

Why Use Docker with ASP.NET Core?

Docker provides:

• Environment consistency (works the same in development and production)

• Isolation from host system

• Simplified CI/CD integration

• Easier scaling and rollback

• Microservices compatibility

For modern DevOps pipelines, containerization is a best practice.

Real-World Analogy

Think of Docker like shipping goods in standardized containers. Regardless of what is inside, ports and ships handle containers uniformly. Azure Web App acts like a managed port that runs your container without worrying about the internal contents.

High-Level Architecture Flow

Developer → Build Docker Image → Push to Azure Container Registry → Azure Web App Pulls Image → Container Runs → Public Endpoint Available

This ensures consistent deployment across environments.

Step 1: Create ASP.NET Core Application

Create a Web API project:

dotnet new webapi -n MyApp
cd MyApp

Step 2: Create Dockerfile

Inside project root, create a file named Dockerfile:

# Build stage
FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
WORKDIR /app
COPY . .
RUN dotnet restore
RUN dotnet publish -c Release -o /publish

# Runtime stage
FROM mcr.microsoft.com/dotnet/aspnet:8.0
WORKDIR /app
COPY --from=build /publish .
EXPOSE 8080
ENTRYPOINT ["dotnet", "MyApp.dll"]

This uses multi-stage build to reduce final image size.

Step 3: Build Docker Image Locally

docker build -t myapp:latest .

Test locally:

docker run -p 8080:8080 myapp

Access via:

http://localhost:8080

Step 4: Push Image to Azure Container Registry (ACR)

Create ACR:

az acr create --resource-group MyResourceGroup --name MyContainerRegistry --sku Basic

Login to ACR:

az acr login --name MyContainerRegistry

Tag image:

docker tag myapp:latest mycontainerregistry.azurecr.io/myapp:latest

Push image:

docker push mycontainerregistry.azurecr.io/myapp:latest

Step 5: Create Azure Web App for Containers

Create App Service Plan:

az appservice plan create --name MyAppServicePlan --resource-group MyResourceGroup --is-linux --sku B1

Create Web App:

az webapp create \
  --resource-group MyResourceGroup \
  --plan MyAppServicePlan \
  --name MyDockerWebApp \
  --deployment-container-image-name mycontainerregistry.azurecr.io/myapp:latest

Configure container registry credentials:

az webapp config container set \
  --name MyDockerWebApp \
  --resource-group MyResourceGroup \
  --docker-custom-image-name mycontainerregistry.azurecr.io/myapp:latest \
  --docker-registry-server-url https://mycontainerregistry.azurecr.io

Azure will pull the image and run the container.

Step 6: Configure Environment Variables

In Azure Portal or CLI:

az webapp config appsettings set \
  --name MyDockerWebApp \
  --resource-group MyResourceGroup \
  --settings ASPNETCORE_ENVIRONMENT=Production

Environment variables should not be hardcoded inside Docker image.

Real Business Scenario: SaaS Application

Consider a SaaS platform serving thousands of users:

• Application is containerized.

• CI/CD pipeline builds image on each commit.

• Image pushed to ACR.

• Azure Web App automatically pulls new image.

• Auto-scaling handles traffic spikes.

If a deployment fails, rollback is as simple as redeploying previous image tag.

Detailed Difference: Traditional App Service vs Web App for Containers