Summary

Running docker build within the Dockerfile folder causes no such file or directory error.

C:\Hello-Blazor\docker build --force-rm -t helloblazor:latest .
Sending build context to Docker daemon  2.653MB
...
COPY failed: stat /var/lib/docker/tmp/docker-builder392878620/Hello-Blazor/Hello-Blazor.csproj: no such file or directory

Move up one folder (parent folder of Dockerfile) to change the build context and provide path to the Dockerfile.

C:\docker build -f .\Hello-Blazor\Dockerfile --force-rm -t helloblazor:latest .

Description

When building a Docker image from a Visual Studio generated Dockerfile, such as a .NET Core project, the error ‘no such file or directory’ can occur if the right build context is missing. In Visual Studio generated solutions and projects, the Solution file (.sln) is often in a parent folder to the Project files and their individual Dockerfiles. This makes the Visual Studio solution folder the root build context to build all projects and this build context is assumed in the compiler generated Dockerfile for projects.

C:.
+---Hello-Blazor.sln    //Build Context
+---Hello-Blazor
|   +---Hello-Blazor.csproj
|   +---Dockerfile

The autogenerated Dockerfile for multi-staged builds will show the solution folder build context in the COPY and RUN operations.

...
FROM mcr.microsoft.com/dotnet/core/sdk:3.1-buster AS build
WORKDIR /src
COPY ["Hello-Blazor/Hello-Blazor.csproj", "Hello-Blazor/"]
RUN dotnet restore "Hello-Blazor/Hello-Blazor.csproj"
...

To build the Docker image, use the solution folder as the build context (current folder) and use the -f parameter to pass the Dockerfile path instead of building directly from the Dockerfile folder.

C:\docker build -f ./Hello-Blazor/Dockerfile --force-rm -t helloblazor:latest .