Container Publishing (No Dockerfile)

Core Principles

No Dockerfile needed — The .NET 10 SDK builds OCI-compliant container images directly from
```
dotnet publish /t:PublishContainer
```
. No Dockerfile to write or maintain.
Chiseled images for production — Use
```
noble-chiseled
```
base images: no shell, no package manager, 7 Linux components vs 100+. Smallest attack surface.
Non-root by default — .NET 10 container images run as the
```
app
```
user automatically. Never override to root in production.
Configuration in the .csproj — All container settings are MSBuild properties, versioned with your project. No separate files to drift.

Patterns

Minimal Container Publish

No project file changes needed. Just publish:

bash

dotnet publish /t:PublishContainer --os linux --arch x64

This creates a container image in your local Docker daemon using the default

aspnet:10.0

base image.

Production-Ready .csproj Configuration

xml

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <ContainerRepository>mycompany/myapp-api</ContainerRepository>
    <ContainerFamily>noble-chiseled</ContainerFamily>
  </PropertyGroup>

  <ItemGroup>
    <ContainerPort Include="8080" Type="tcp" />
    <ContainerEnvironmentVariable Include="ASPNETCORE_HTTP_PORTS" Value="8080" />
    <ContainerEnvironmentVariable Include="DOTNET_EnableDiagnostics" Value="0" />
    <ContainerLabel Include="org.opencontainers.image.vendor" Value="MyCompany" />
  </ItemGroup>

</Project>

Publishing to a Registry

Authenticate with

docker login

first, then specify the registry:

bash

# GitHub Container Registry
docker login ghcr.io
dotnet publish /t:PublishContainer --os linux --arch x64 \
    -p ContainerRegistry=ghcr.io \
    -p ContainerImageTag=1.0.0

# Azure Container Registry
az acr login --name myregistry
dotnet publish /t:PublishContainer --os linux --arch x64 \
    -p ContainerRegistry=myregistry.azurecr.io

# Docker Hub (requires username prefix in repository)
dotnet publish /t:PublishContainer --os linux --arch x64 \
    -p ContainerRegistry=docker.io \
    -p ContainerRepository=myuser/myapp

Multi-Architecture Images

Build images for multiple platforms with a single publish:

xml

<PropertyGroup>
    <RuntimeIdentifiers>linux-x64;linux-arm64</RuntimeIdentifiers>
    <ContainerRuntimeIdentifiers>linux-x64;linux-arm64</ContainerRuntimeIdentifiers>
</PropertyGroup>

bash

dotnet publish /t:PublishContainer

This produces an OCI Image Index — registries serve the correct architecture automatically.

Multiple Tags

bash

# Bash — note the quoting for semicolons
dotnet publish /t:PublishContainer --os linux --arch x64 \
    -p ContainerImageTags='"1.0.0;latest"'

Or in the project file:

xml

<ContainerImageTags>1.0.0;latest</ContainerImageTags>

Save as Tarball (No Docker Required)

No container runtime needed on the build machine. Useful for CI scanning:

bash

dotnet publish /t:PublishContainer --os linux --arch x64 \
    -p ContainerArchiveOutputPath=./images/myapp.tar.gz

# Scan with Trivy before pushing
trivy image --input ./images/myapp.tar.gz

Chiseled Image Variants

ContainerFamily	Use Case	Shell	Size
(default)	General purpose (Debian)	Yes	~220 MB
`noble-chiseled`	Production (no shell)	No	~110 MB
`noble-chiseled-extra`	Production with localization (ICU)	No	~120 MB
`alpine`	Small size, has shell	Yes	~112 MB

xml

<!-- Standard chiseled (InvariantGlobalization=true) -->
<ContainerFamily>noble-chiseled</ContainerFamily>

<!-- Chiseled with ICU for localization -->
<ContainerFamily>noble-chiseled-extra</ContainerFamily>

For Native AOT, the SDK auto-selects

chiseled-aot

xml

<PublishAot>true</PublishAot>
<!-- SDK picks runtime-deps:10.0-noble-chiseled-aot automatically -->

CI/CD with GitHub Actions

yaml

jobs:
  publish:
    runs-on: ubuntu-latest
    permissions:
      packages: write
    steps:
      - uses: actions/checkout@v5
      - uses: actions/setup-dotnet@v5
        with:
          dotnet-version: '10.0.x'
      - uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
      - run: |
          dotnet publish src/MyApp.Api/MyApp.Api.csproj \
            /t:PublishContainer --os linux --arch x64 \
            -p ContainerRegistry=ghcr.io \
            -p ContainerRepository=${{ github.repository_owner }}/myapp \
            -p ContainerImageTag=${{ github.sha }}

Anti-patterns

Don't Use the Deprecated Property Names

xml

<!-- BAD — ContainerImageName is deprecated -->
<ContainerImageName>myapp</ContainerImageName>

<!-- GOOD — use ContainerRepository -->
<ContainerRepository>myapp</ContainerRepository>

Don't Use PublishProfile=DefaultContainer

bash

# BAD — old approach, inconsistent across project types
dotnet publish -p:PublishProfile=DefaultContainer

# GOOD — use the MSBuild target directly
dotnet publish /t:PublishContainer

Don't Forget to Target Linux

bash

# BAD on Windows — may produce a Windows container
dotnet publish /t:PublishContainer

# GOOD — explicitly target Linux
dotnet publish /t:PublishContainer --os linux --arch x64

Don't Skip Authentication Before Push

bash

# BAD — fails with CONTAINER1013 error
dotnet publish /t:PublishContainer -p ContainerRegistry=ghcr.io

# GOOD — authenticate first
docker login ghcr.io
dotnet publish /t:PublishContainer -p ContainerRegistry=ghcr.io

Don't Use SDK Publishing When You Need OS Packages

xml

<!-- BAD — SDK container publish cannot run apt-get or install native packages -->
<!-- There is no RUN equivalent -->

<!-- GOOD — create a custom base image with a Dockerfile first, then reference it -->
<ContainerBaseImage>myregistry/custom-base:1.0</ContainerBaseImage>

Decision Guide

Scenario	Recommendation
Standard ASP.NET Core API	SDK container publishing with `noble-chiseled`
Worker service / console app	SDK container publishing (native .NET 10 support)
Needs native OS packages	Dockerfile (or custom base image + SDK publishing)
Azure Functions	Dockerfile (not supported by SDK publishing)
CI without Docker daemon	Tarball output with `ContainerArchiveOutputPath`
Multi-arch deployment (x64 + arm64)	`ContainerRuntimeIdentifiers` property
Production image size	`noble-chiseled` (~110 MB) or Native AOT (~10 MB)
Local development	`dotnet publish /t:PublishContainer --os linux --arch x64`
Registry push	`ContainerRegistry` + `docker login`

container-publish

NPX Install

Tags

SKILL.md Content

Container Publishing (No Dockerfile)

Core Principles

Patterns

Minimal Container Publish

Production-Ready .csproj Configuration

Publishing to a Registry

Multi-Architecture Images

Multiple Tags

Save as Tarball (No Docker Required)

Chiseled Image Variants

CI/CD with GitHub Actions

Anti-patterns

Don't Use the Deprecated Property Names

Don't Use PublishProfile=DefaultContainer

Don't Forget to Target Linux

Don't Skip Authentication Before Push

Don't Use SDK Publishing When You Need OS Packages

Decision Guide