Aspnetcore.docs: Explanation for copy steps in Dockerfile template

[guardrex]

From @AbdoHassanUMG ...

Why the project file is copied individually before dotnet restore then a "COPY . . " statement is execute later ?

What's the benefit of doing a csproj copy instead of doing a "COPY . ." before the dotnet restore?

Docs tag 5847cdf8-1823-7740-6e43-030902b26ad8

@UsmanMohammad

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Document Details

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• ID: 3653642e-61ef-717b-5436-9bd0a3c4e6f4
• Version Independent ID: 80c1ce51-46fb-0693-525a-7cad37150c7b
• Content: Docker images for ASP.NET Core
• Content Source: aspnetcore/host-and-deploy/docker/building-net-docker-images.md
• Product: aspnet-core
• Technology: aspnetcore-hostdeploy
• GitHub Login: @tdykstra
• Microsoft Alias: tdykstra

[serpent5]

In case it’s helpful, I answered this exact question on Stack Overflow a few months ago: https://stackoverflow.com/questions/53460002/how-to-use-dotnet-restore-properly-in-dockerfile/54832279#54832279.

[AbdoHassanUMG]

Brilliant ! very smart optimisation
Thanks @serpent5

[Nirmal4G]

What happens when there are Directory.Build.props/targets and Custom SDKs involved, and the project files are in different folders with a distinct directory structure?

You can't do this

# copy csproj and restore as distinct layers
COPY *.sln .
COPY aspnetapp/*.csproj ./aspnetapp/
RUN dotnet restore

The COPY command will not mirror the directory structure, which most bigger solutions and projects are composed of.

RELATED: moby/moby#39530

It may work for samples and templates (_with no directory structure_), but not real world projects.

[Rick-Anderson]

Moved to #16250

[Rick-Anderson]

@serpent5 should we add your SO post info to this doc?

[serpent5]

@Rick-Anderson I just realised I didn't respond to this one. I've opened up a PR for it.