CODEWITHSUNDEEP
.netdocker.net-core
user1765862
user1765862

Reputation: 14155

.net core image failes on build when using alpine instead of aspnet:3.1

I have working Dockerfile content

    FROM mcr.microsoft.com/dotnet/core/sdk:3.1 as build
    WORKDIR /app 
    
    # copy csproj and restore as distinct layers
    COPY ./Honda.Domain/Honda.Domain.csproj ./Honda.Domain/
    COPY ./Honda.API/Honda.API.csproj Honda.API/
    
    RUN dotnet restore Honda.API/Honda.API.csproj
    
    # copy everything else and build app
    COPY . ./
    WORKDIR /app/Honda.API/
    RUN dotnet publish -c Release -o publish/
    
    FROM mcr.microsoft.com/dotnet/core/aspnet:3.1
    WORKDIR /app
    COPY --from=build /app/Honda.API/publish  .
    
    ENV ASPNETCORE_URLS=https://+:5001;http://+:5000 
    ENTRYPOINT ["dotnet", "Honda.API.dll"]

but when I try to optimize the image using alpine image instead of aspnet:3.1

    FROM mcr.microsoft.com/dotnet/core/sdk:3.1 as build
    WORKDIR /app 
    
    # copy csproj and restore as distinct layers
    COPY ./Honda.Domain/Honda.Domain.csproj ./Honda.Domain/
    COPY ./Honda.API/Honda.API.csproj Honda.API/
    
    RUN dotnet restore Honda.API/Honda.API.csproj
    
    # copy everything else and build app
    COPY . ./
    WORKDIR /app/Honda.API/

    RUN dotnet publish -c Release -o publish/

    FROM alpine:3.9.4 #**************************** change 1 ***************
    # Add some libs required by .NET runtime 
    RUN apk add --no-cache libstdc++ libintl icu #* change 2***************

    WORKDIR /app
    COPY --from=build /app/Honda.API/publish  .
    
    ENV ASPNETCORE_URLS=https://+:5001;http://+:5000 
    ENTRYPOINT ["dotnet", "Honda.API.dll"]

but with the second image I'm getting error on docker-compose up --build

ERROR: for honda-api Cannot start service honda-api: OCI runtime create failed: container_linux.go:349: starting container process caused "exec: "dotnet": executable file not found in $PATH": unknown ERROR: Encountered errors while bringing up the project.

Any ideas?

Upvotes: 1

Views: 1465

Answers (2)

Jesús López
Jesús López

Reputation: 9241

You should use:

FROM mcr.microsoft.com/dotnet/aspnet:3.1-alpine

This includes asp.net core 3.1 runtime on alpine linux 3.16

Please see: https://hub.docker.com/_/microsoft-dotnet-aspnet/

Upvotes: 0

Ziaullah Khan
Ziaullah Khan

Reputation: 2244

FROM alpine:3.9.4 #**************************** change 1 ***************

https://hub.docker.com/_/alpine - referring this link

Alpine Linux is a Linux distribution. The image is only 5 MB in size. So you essentially have go only a Linux vanilla machine.. You'll have to install the .NET Core Runtime.

Now you are right when you RUN apk add sequence but it's not enough. You'll have a lot more apk add before you setup a fully functional .NET Core runtime.

And btw that's also against docker philosophy. The docker philosophy is that you let the creator of technology create a base image for you. With the owners creating the image you'll always be sure that it works.

While you focus completely on developing your end of the application. In your case .NET Core image by Microsoft. I'd recommend docker pull mcr.microsoft.com/dotnet/runtime

If you want a smaller image pick the .NET Core Runtime image. The last time I checked it was about 200MB and it has everything for running a .net core dll or exe.

Upvotes: 1

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