390 words (approximately 2 mins)

Configure Container Image

Most configuration is handled through MSBuild properties. Exception: RUN commands require a Dockerfile.

ContainerBaseImage

The image used as the basis for the image being created.

<PropertyGroup>
<ContainerBaseImage>mcr.microsoft.com/_net/runtime:6.0</ContainerBaseImage>
</PropertyGroup>

Defaults:

  • If project is self-contained, the mcr.microsoft.com/_net/runtime-deps image is used.
  • If project is an ASP.NET Core project, the mcr.microsoft.com/_net/aspnet image is used.
  • Otherwise the mcr.microsoft.com/_net/runtime image is used.

ContainerRuntimeIdentifier

The OS and architecture used by the container of the ContainerBaseImage supports more than one platform.

<PropertyGroup>
<ContainerRuntimeIdentifier>linux-amd64</ContainerRuntimeIdentifier>
</PropertyGroup>

Default: Set to value of the RuntimeIdentifier (-r option of dotnet publish command)

ContainerRegistry

The destination registry.

<PropertyGroup>
<ContainerRegistry>registry.mycorp.com:1234</ContainerRegistry>
</PropertyGroup>

Default: local Docker daemon

ContainerImageName

The name of the image.

<PropertyGroup>
<ContainerImageName>my-app</ContainerImageName>
</PropertyGroup>

Default: AssemblyName of project is used.

ContainerImageTags

Tags generated for the image.

<PropertyGroup>
<ContainerImageTag>1.2.3-alpha2;another-tag</ContainerImageTag>
</PropertyGroup>

Default: Version of the project is used as tag value.

ContainerWorkingDirectory

The working directory of the container.

<PropertyGroup>
<ContainerWorkingDirectory>/bin</ContainerWorkingDirectory>
</PropertyGroup>

Default: /app

ContainerPort

TCP or UDP ports that are added to the list of known ports for the container.

<ItemGroup>
<ContainerPort Include="80" Type="tcp" />
</ItemGroup>

ContainerLabel

A metadata label for the container.

<ItemGroup>
<ContainerLabel Include="org.contoso.businessunit" Value="contoso-university" />
</ItemGroup>

ContainerEnvironmentVariable

Environment variables for the container.

<ItemGroup>
<ContainerEnvironmentVariable Include="LOGGER_VERBOSITY" Value="Trace" />
</ItemGroup>

ContainerEntrypoint

The executable that is called when the container is started.

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Default:

  • For builds that create an app host, the app host is used as the Entrypoint.
  • For builds that don’t create an executable, dotnet path/to/app.dll is used.

ContainerEntrypointArgs

Arguments passed to the ContainerEntrypoint.

<ItemGroup>
<!-- Assuming the ContainerEntrypoint defined above,
this would be the way to update the database by
default, but let the user run a different EF command. -->
<ContainerEntrypointArgs Include="database" />
<ContainerEntrypointArgs Include="update" />

<!-- This is the shorthand syntax for the same idea -->
<ContainerEntrypointArgs Include="database;update" />
</ItemGroup>

Default: None

Process to Containerize an App

  1. Clean, Restore, Publish
dotnet clean
dotnet restore
dotnet publish -c Release
  1. Create Dockerfile Create the Dockerfile as file Dockerfile in the directory containing the csproj file:
FROM mcr.microsoft.com/_net/runtime:7.0-bullseye-slim
WORKDIR /blsrpt
COPY bin/Release/net7.0/publish .
RUN apt-get update
RUN apt-get install -y libfreetype6
RUN apt-get install -y libfontconfig1
RUN apt-get install -y fontconfig
ENTRYPOINT ["dotnet", "blsrpt.dll"]
  1. Build image
docker build -t *registry*/*image-name*:*tag* .

Publish App as Container Image

Requires docker.

# For non-web apps:
dotnet publish --os linux --arch x64 /t:PublishContainer -c Release

# For web apps:
dotnet publish --os linux --arch x64 -p:PublishProfile=DefaultContainer