CODEWITHSUNDEEP
dockerasp.net-core
Marcus Lanvers
Marcus Lanvers

Reputation: 411

Why can i not find MSBuild in multi solution asp.net-core application within a docker container

I am trying to contain my asp.net-core application into a docker container. As I use the Microsoft-secret-store for saving credentials, I need to run a dotnet user-secrets command withing my container. The application needs to read these credentials when starting, so I have to run the command prior to starting my application. When trying to do that in my Dockerfile I get the error:

 ---> Running in 90f974a06d83
Could not find a MSBuild project file in '/app'. Specify which project to use with the --project option.

I tried building my application first and then building a container with the already build dll, but that gave me the same error. I also tried connecting to the container with ENTRYPOINT ["/bin/bash"] and then looking around in the container. It seems that the /app folder that gets created does not have the .csproj files included. Im not sure if that could be an error.

My Dockerfile

FROM mcr.microsoft.com/dotnet/core/sdk:2.2 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/core/sdk:2.2-stretch AS build
WORKDIR /src
COPY ["Joinme.Facade/Joinme.Facade.csproj", "Joinme.Facade/"]
COPY ["Joinme.Domain/Joinme.Domain.csproj", "Joinme.Domain/"]
COPY ["Joinme.Business/Joinme.Business.csproj", "Joinme.Business/"]
COPY ["Joinme.Persistence/Joinme.Persistence.csproj", "Joinme.Persistence/"]
COPY ["Joinme.Integration/Joinme.Integration.csproj", "Joinme.Integration/"]
RUN dotnet restore "Joinme.Facade/Joinme.Facade.csproj"
COPY . .
WORKDIR "/src/Joinme.Facade"
RUN dotnet build "Joinme.Facade.csproj" -c Release -o /app

FROM build AS publish
RUN dotnet publish "Joinme.Facade.csproj" -c Release -o /app

FROM base AS final
WORKDIR /app
COPY --from=publish /app .
RUN dotnet user-secrets set "jwt:secret" "some_password"
ENTRYPOINT ["dotnet", "Joinme.Facade.dll"]

My expected results are that the secret gets set, so I can start the container without it crashing.

Upvotes: 2

Views: 2021

Answers (1)

Chris Pratt
Chris Pratt

Reputation: 239300

Plain and simple: the operation is failing because at this stage, there is no *.csproj file(s), which the user-secrets command requires. However, this is not what you should be doing anyways for a few reasons:

  1. User secrets are not for production. You can just as easily, or in fact more easily, set an environment variable here instead, which doesn't require dotnet or the SDK.

    ENV jwt:secret some_password

  2. You should not actually be storing secrets in your Dockerfile, as that goes into your source control, and is exposed as plain text. Use Docker secrets, or an external provider like Azure Key Vault.

  3. You don't want to build your final image based on the SDK, anyways. That's going to make your container image huge, which means both longer transfer times to/from the container registry and higher storage/bandwidth costs. Your final image should be based on the runtime, or even something like alpine, if you publish self-contained (i.e. keep it as small as possible).

Upvotes: 3

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