[.NET] Optimising .NET Core with Multi-Platform Docker Images: A Complete Guide

FROM mcr.microsoft.com/dotnet/aspnet:7.0 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/sdk:7.0 AS build
WORKDIR /src
COPY ["SampleApi/SampleApi.csproj", "SampleApi/"]
RUN dotnet restore "SampleApi/SampleApi.csproj"
COPY . .
WORKDIR "/src/SampleApi"
RUN dotnet build "SampleApi.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "SampleApi.csproj" -c Release -o /app/publish /p:UseAppHost=false

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "SampleApi.dll"]

# 1. Changes this image from 'aspnet:7.0' to 'aspnet:7.0-alpine'
FROM mcr.microsoft.com/dotnet/aspnet:7.0-alpine AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

# 2. Changes this image from 'sdk:7.0' to 'sdk:7.0-alpine'
FROM mcr.microsoft.com/dotnet/sdk:7.0-alpine AS build
WORKDIR /src
COPY ["SampleApi/SampleApi.csproj", "SampleApi/"]
RUN dotnet restore "SampleApi/SampleApi.csproj"
COPY . .
WORKDIR "/src/SampleApi"
RUN dotnet build "SampleApi.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "SampleApi.csproj" -c Release -o /app/publish /p:UseAppHost=false

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "SampleApi.dll"]

# 1. Changes this image from 'aspnet:7.0-alpine' to 'runtime-deps:7.0-alpine'
FROM mcr.microsoft.com/dotnet/runtime-deps:7.0-alpine AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/sdk:7.0-alpine AS build
WORKDIR /src
COPY ["SampleApi/SampleApi.csproj", "SampleApi/"]
RUN dotnet restore "SampleApi/SampleApi.csproj"
COPY . .
WORKDIR "/src/SampleApi"
RUN dotnet build "SampleApi.csproj" -c Release -o /app/build

FROM build AS publish

# 2. updated 'dotnet publish' options
RUN dotnet publish "SampleApi.csproj" -c Release -o /app/publish \
  --runtime alpine-x64 \
  --self-contained true \
  /p:PublishTrimmed=true \
  /p:PublishSingleFile=true

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .

# 3. updated the endpoint, the application path no need to mentiond the '.dll' anymore.
ENTRYPOINT ["./SampleApi"]

FROM mcr.microsoft.com/dotnet/runtime-deps:7.0-alpine AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/sdk:7.0-alpine AS build
WORKDIR /src
COPY ["SampleApi/SampleApi.csproj", "SampleApi/"]
RUN dotnet restore "SampleApi/SampleApi.csproj"
COPY . .
WORKDIR "/src/SampleApi"
RUN dotnet build "SampleApi.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "SampleApi.csproj" -c Release -o /app/publish \
  --runtime alpine-x64 \
  --self-contained true \
  /p:PublishTrimmed=true \
  /p:PublishSingleFile=true

FROM base AS final

# 1. Create a new user and change directory ownership
RUN adduser --disabled-password \
  --home /app \
  --gecos '' dotnetuser && chown -R dotnetuser /app

# 2. Impersonate into the new user
USER dotnetuser
WORKDIR /app

COPY --from=publish /app/publish .
ENTRYPOINT ["./SampleApi"]

FROM mcr.microsoft.com/dotnet/runtime-deps:7.0-alpine AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

# 1. Add 2 (BUILDPLATFORM and TARGETARCH) arguments and add 'platform' parameter to the FROM statement.
FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:7.0-alpine AS build
ARG TARGETARCH
ARG BUILDPLATFORM

WORKDIR /src
COPY ["SampleApi/SampleApi.csproj", "SampleApi/"]
RUN dotnet restore "SampleApi/SampleApi.csproj"
COPY . .
WORKDIR "/src/SampleApi"

# 2. add '-a $TARGETARCH' to the 'dotnet build' command.
RUN dotnet build "SampleApi.csproj" -c Release -o /app/build -a $TARGETARCH

FROM build AS publish

# 2. add '-a $TARGETARCH' to the 'dotnet publish' command.
RUN dotnet publish "SampleApi.csproj" -c Release -o /app/publish \
    #--runtime alpine-x64 \
    --self-contained true \
    /p:PublishTrimmed=true \
    /p:PublishSingleFile=true \
    -a $TARGETARCH

# 3. Add 2 (BUILDPLATFORM and TARGETARCH) arguments and add 'platform' parameter to the FROM statement.
FROM --platform=$BUILDPLATFORM base AS final
ARG TARGETARCH
ARG BUILDPLATFORM

RUN adduser --disabled-password \
  --home /app \
  --gecos '' dotnetuser && chown -R dotnetuser /app

USER dotnetuser
WORKDIR /app

COPY --from=publish /app/publish .
ENTRYPOINT ["./SampleApi"]

# Build Docker for x64 processor
docker build --platform="linux/amd64" -f Dockerfile -t sampleapi-x64:latest .

# Build image for arm64 processor
docker build --platform="linux/arm64" -f Dockerfile -t sampleapi-arm64:latest .

# All together, build image for multi-platform with docker buildx
docker buildx build --platform="linux/amd64,linux/arm64" -f Dockerfile -t sampleapi:latest .

name: Docker-Publish

on:
  workflow_call:
    inputs:
      # The location of the Dockerfile parameter.
      dockerFile:
        required: true
        type: string
        description: The location of the Dockerfile.

      # The context path of the project parameter.
      context:
        default: .
        type: string
        description: The context path of the project.

      # The docker platforms parameter with default value is "linux/arm64 and linux/amd64"
      platforms:
        default: linux/arm64,linux/amd64
        type: string
        description: The docker platforms parameter with default value is "linux/arm64 and linux/amd64".

      # The name of the docker image parameter.
      imageName:
        required: true
        type: string
        description: The name of the docker image.

      # The version parameter of the image with default value is current date-time.
      version:
        default: $(date +%s)
        type: string
        description: The version of the image with default value is current date-time.
    secrets:
      # The DOCKER_USERNAME secret parameter.
      DOCKER_USERNAME:
        required: true
        description: The docker hub user name.
      # The DOCKER_TOKEN secret parameter.
      DOCKER_TOKEN:
        required: true
        description: The docker hub PAT token.

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v3

      # Setup Buildx
      - name: Docker Setup Buildx
        uses: docker/setup-buildx-action@v2.9.1
        with:
          platforms: ${{ inputs.platforms }}

      # Login to docker hub
      - name: Docker Login
        uses: docker/login-action@v2.0.0
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_TOKEN }}
          ecr: auto
          logout: true

      # Pull the previous image from docker hub to use it as cache to improve the image build time.
      - name: docker pull cache image
        continue-on-error: true
        run: docker pull ${{ inputs.imageName }}:latest

      # Setup QEMU
      - name: Set up QEMU
        uses: docker/setup-qemu-action@v2

      # Build and Publish to Docker
      - name: Build the Docker image
        run: |
          docker buildx build ${{ inputs.context }} --file ${{ inputs.dockerFile }} \
            --tag ${{ inputs.imageName }}:${{ inputs.version }} \
            --tag ${{ inputs.imageName }}:latest \
            --cache-from=${{ inputs.imageName }}:latest \
            --push --platform=${{ inputs.platforms }}

name: Docker-Buildx

on:
  push:
    branches:
      - "main"

jobs:
  dotnet_release_job:
    # TODO: Update this path according to your git repository.
    uses: baoduy/ShareWorkflows/.github/workflows/docker-publish.yaml@main
    with:
      # The location of the Dockerfile parameter.
      dockerFile: "01_Multi_platform_docker_image_for_NET/SampleApi/Dockerfile"
      # The context path of the project parameter.
      context: '"./01_Multi_platform_docker_image_for_NET"'
      # The name of the docker image parameter.
      imageName: "baoduy2412/sample-01-api"
      # The docker platforms parameter.
      platforms: linux/arm64,linux/amd64
    secrets:
      # The DOCKER_USERNAME secret parameter.
      DOCKER_USERNAME: ${{ secrets.DOCKER_USERNAME }}
      # The DOCKER_TOKEN secret parameter.
      DOCKER_TOKEN: ${{ secrets.DOCKER_TOKEN }}