bug#48178: Out of memory error when generating a docker-image.

[Leo Famulari <leo@famulari.name>]

On Mon, May 03, 2021 at 12:09:36AM +0200, Roel Janssen wrote:
> Looking at 'guix/scripts/system.scm', it seems that we always pass 256M
> of memory to the VM.  After bumping that to 4096M, I was able to
> produce a docker image.

Can you test somes values that are in between? Like, 512M, 1024M, etc,
until we know how much is actually required? If 512M is enough, I don't
see a problem with increasing the hard-coded value to that.

> I'd like to see what we can do here.  Assigning too little memory leads
> to problems generating the container, but assigning too much memory wil
> l cause problems for computing machines that don't have much memory to
> spare.

There are some use cases for this code that we'd like to work on
low-resource machines (`guix system vm`), and other use cases (like
building Docker images) that shouldn't be expected to work on machines
with limited RAM.

> Would it be a good idea to make it configurable at run-time?

Yeah, maybe.