Mount docker volume to host machine path

Question

I need to access test result files in the host from the container. I know that I need to create a volume which maps between host and container, like below, but I get nothing written to the host.

docker run --rm -it -v <host_directory_path>:<container_path> imagename

Dockerfile:

FROM microsoft/dotnet:2.1-sdk AS builder
WORKDIR /app
COPY ./src/MyApplication.Program/MyApplication.Program.csproj ./src/MyApplication.Program/MyApplication.Program.csproj
COPY nuget.config ./
WORKDIR ./src/MyApplication.Program/
RUN dotnet restore
WORKDIR /app
COPY ./src ./src
WORKDIR ./src/MyApplication.Program/
RUN dotnet build MyApplication.Program.csproj -c Release

FROM builder as tester
WORKDIR /app
COPY ./test/MyApplication.UnitTests/MyApplication.UnitTests.csproj ./test/MyApplication.UnitTests/MyApplication.UnitTests.csproj
WORKDIR ./test/MyApplication.UnitTests/
RUN dotnet restore
WORKDIR /app
COPY ./test ./test
WORKDIR ./test/MyApplication.UnitTests/
RUN dotnet test /p:CollectCoverage=true /p:CoverletOutputFormat=cobertura
ENTRYPOINT ["dotnet", "reportgenerator", "-reports:coverage.cobertura.xml", "-targetdir:codecoveragereports", "-reportTypes:htmlInline"]

The command at the entry point is working correctly. It is writing the output to the MyApplication.UnitTests/codecoveragereports directory, but not to the host directory.

My docker run looks as follows:

docker run --rm -it -v /codecoveragereports:/app/test/MyApplication.UnitTests/codecoveragereports routethink.tests:latest

What could I be doing wrong?

Answer 1

Looks like a permission issue.

-v /codecoveragereports:/app/***/codecoveragereports is mounting a directory under the root / which is dangerous and you may not have the permission.

It's better to mount locally, like -v $PWD/codecoveragereports:/app/***/codecoveragereports, where $PWD is an environment variable equal to the current working directory.