Run docker inside docker - docker

Question

I have some dll (.net core app that can be run on linux) that does database migrations.
It receives few arguments one of them being dll that contains my applications database migration.
I created one image of all (migration application and my project that contains migration, EF core migrations) this and run them using docker run -e Server=xxx -e DatabaseName=xxx -e UserId=xxx -e Password=xxx migrate:v0.3.5
This is my docker image:
#See https://aka.ms/containerfastmode to understand how Visual Studio uses this Dockerfile to build your images for faster debugging.
FROM mcr.microsoft.com/dotnet/aspnet:5.0-buster-slim AS base
WORKDIR /app
FROM mcr.microsoft.com/dotnet/sdk:5.0-buster-slim AS build
WORKDIR /src
COPY ["ef-migrations-cli/EfMigrationsCLI/EfMigrationsCLI/EfMigrationsCLI.csproj", "ef-migrations-cli/EfMigrationsCLI/EfMigrationsCLI/"]
RUN dotnet restore "ef-migrations-cli/EfMigrationsCLI/EfMigrationsCLI/EfMigrationsCLI.csproj"
COPY . .
WORKDIR /src
COPY ["RED.Database.Server/RED.Database.Server.csproj", "RED.Database.Server/"]
COPY . .
WORKDIR "/src/ef-migrations-cli/EfMigrationsCLI/EfMigrationsCLI"
FROM build AS publish
RUN dotnet publish "EfMigrationsCLI.csproj" -c Release -o /app/publish
WORKDIR /src
WORKDIR "/src/RED.Database.Server"
FROM build AS publish2
RUN find /src/RED.Database.Server/RED.Database.Server.csproj -name *.csproj
RUN dotnet publish "/src/RED.Database.Server/RED.Database.Server.csproj" -c Release -o /app/publish
FROM base AS final
WORKDIR /app
COPY --from=publish2 /app/publish .
COPY --from=publish /app/publish .
ENV Server "please_set_Server_env_variable_when_docker_run"
ENV DatabaseName "please_set_DatabaseName_env_variable_when_docker_run"
ENV UserId "please_set_UserId_env_variable_when_docker_run"
ENV Password "please_set_Password_env_variable_when_docker_run"
ENV DatabaseContext "REDDatabaseContext"
ENV MigrationsAssembly "RED.Database.Server.dll"
ENTRYPOINT [ "sh", "-c", "dotnet EfMigrationsCLI.dll --userid=${UserId} --password=${Password} --databasename=${DatabaseName} --server=${Server} --databaseContext=REDDatabaseContext --migrationsAssembly=${MigrationsAssembly}" ]
I would like to separate my migration dll as separate docker image (because it will not change very often , or ever) and have another image that builds my project that contains migrations and pass it to the first container.
How to achieve this?

Answer 1

I don't understand if you want to build an image in a container OR fetch an image inside your container BUT
I think you can watch this https://hub.docker.com/_/ubuntu in the Locales chapter, you can see that it is possible to run apt-get command to install https://docs.docker.com/engine/install/ubuntu/
So I suppose, you can
RUN apt-get install apt-transport-https ca-certificates curl gnupg lsb-release
RUN curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
RUN echo "deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
RUN apt-get update && apt-get install docker-ce docker-ce-cli containerd.io
RUN docker run hello-world
Then you "just" have to adapt to your needs.
Hope it is a good track for you to follow