Pushing NuGet packages built in Docker by running the container

In a previous post I described how you could build NuGet packages in Docker. One of the advantages of building NuGet packages in Docker is that you can don't need any dependencies installed on the build-server itself, you can install all the required dependencies in the Docker container instead. One of the disadvantages of this approach is that getting at the NuGet packages after they've been built is more tricky - you have to run the image to get at the files.