Re: [Userops] Why is it hard to move from one machine to another? An analysis.

[Bob Mottram]

On Thu, Apr 09, 2015 at 11:27:27AM -0400, Dave Crossland wrote:
> > I think there are much better ways that we can isolate application
> > dependencies.  Bundler and co. are useful only because system package
> > managers haven't traditionally allowed for installing to a directory
> > that isn't '/'.  Language-specific package managers let you install
> > anywhere, but they are so narrow in scope that you typically need to use
> > more than one of them in addition to your distro's package manager to
> > get any real work done.  So, a Ruby on Rails application with a
> > JavaScript client may need apt, npm, and bundler in order to obtain all
> > of the pieces necessary for it to work.  Terrible.  The distros we use
> > should provide a package manager that allow us to do this kind of
> > dependency isolation with all packages, not just Ruby/Python/JavaScript
> > stuff, while at the same de-duplicating the files used in multiple
> > "bundles" throughout the system.  Then we'd only need one package
> > manager.
> 
> That exists, it's called Docker :)


Maybe Docker and containers are the way to go, but  I have some concerns.
Installing initially from a Dockerfile, or equivalent, might be ok but there
is then the problem of keeping the container up to date with security
patches, application upgrades and wotnot. If upgrades involve rebuilding
from a Dockerfile then with my current server configuration that could take
several hours.

If the server is powerful enough then there could be two partitions in which
you have an active and currently building partition which then swap over.
Maybe some of the latest octacore SBCs might be able to handle that without
there being too much of a performance hit.

Another problem is detecting when a rebuild should occur. Currently I don't
know of any mechanism which would initiate that, and something new would need
to be written to check upstream repos for changes.