[Nix-dev] Is there a definite list of pre-reqs for nix for RPMs

[Tony White]

2009/7/21 Milind Parikh <milindparikh at gmail.com>:
> "Using nix-store --export and nix-store --import, so that you can
> install nix on machines running centos (Or any other Linux distro that
> runs more current upstream packages) First and then just distribute
> the application(s)?
> Is that what you mean by portable applications? Are you interested in
> using nix to distribute binaries in a portable way?"
>
> In one word : yes
>
> I am interested in assuring someone that when postgres is dropped on a
> server (linux), it just will work. Of course, postgres is a metaphor.
>
> Secondly, from security audit perspective, when libc has to be updated, all
> packages will have the correct references to libc. Once again, package (as
> is libc) is a metaphor; qa still has to be done; but there is simply no
> better way of building. If it does not work (libc upgrade), there can be
> nothing else to be done than to roll back or accept bugs.
>
> It seems, that the first step in this, is to ensure that nix will install
> and operate on a given distro (kind of the bootstrapping process for the
> problem space of nix). Hence the question.
>
>
>
>
> On Mon, Jul 20, 2009 at 3:32 PM, Tony White <tonywhite100 at googlemail.com>
> wrote:
>>
>> 2009/7/20 Milind Parikh <milindparikh at gmail.com>:
>> > "RPM packages of Nix can be downloaded from http://nixos.org/. These
>> > RPMs
>> > should work for most fairly recent releases of SuSE and Red Hat Linux.
>> > They
>> > have been known to work work on SuSE Linux 8.1 and 9.0, and Red Hat 9.0.
>> > In
>> > fact, it should work on any RPM-based Linux distribution based on glibc
>> > 2.3
>> > or later."
>> >
>> >
>> > Doesn't work on centos 5.3 until you upgrade llibstdc++ to the latest
>> > version (that is not even available in yum repos).
>> >
>> > My question, though , is more general. The use case is "portable
>> > applications" (though not under nixox).
>> >
>> >
>> > Regards
>> > -- Milind
>> >
>> >
>> > _______________________________________________
>> > nix-dev mailing list
>> > nix-dev at cs.uu.nl
>> > https://mail.cs.uu.nl/mailman/listinfo/nix-dev
>> >
>> >
>>
>> Hi Milind,
>> Do you want to do something like this :
>>
>> http://hydra.nixos.org/build/47813/download/1/manual/#sec-sharing-packages
>>
>> Using nix-store --export and nix-store --import, so that you can
>> install nix on machines running centos (Or any other Linux distro that
>> runs more current upstream packages) First and then just distribute
>> the application(s)?
>> Is that what you mean by portable applications? Are you interested in
>> using nix to distribute binaries in a portable way?
>>
>> Sorry if I misunderstand.
>>
>> Thanks,
>> Tony
>
>

Hi Milind,
Your postgres would work but you would need to configure your own
custom postgres settings (Maybe using the expression that builds the
package or other method eg script or ssh) and importantly start or
restart the upstart or sysvinit process to control the postgres daemon
on the machine. But only because postgres is used generally as a
daemon process and I guess needs to be configured to suit it's
deployment task.
You shouldn't generally with most software (Unless you want to make a
special configuration) need to do anything exotic to any software that
doesn't use a daemon.

Being specific about which software that you want to deploy and
finding out if the package already exists in the nixpkg collection
will help you answer whether or not you can use nix easily to deploy
software x y or z. Creating your own expressions for software that is
not in nixpkgs will require you to learn a bit of nix expression
language (Easy if you study existing expressions, read the manual and
ask for help on the list or irc if you get stuck.)
If the software you want is in the nixpkg collection, you can download
the software package straight from a channel built by the nix build
farm (Hydra,) Instead of building the software from source code using
the expressions.
Then you can distribute it using the nix-store --export or
nix-copy-closure commands to the other machines that you want to
deploy the software onto.

nix-store --export will copy the software you want to distribute and
all it's dependencies into a file that you can drop onto a machine.
nix-copy-closure would maybe be even better for many machines over a
network and has a similar result but over ssh.

I'm pretty sure I understand it like this (And someone correct me if
I'm wrong please) That the nix environment is separate from the centos
environment. So for instance, a libc update in a nix store will not
effect the centos libc because the dependencies are in the nix store
and if libc was a dependency it would be copied across.
So updates to libc in either the nix store or the centos rpm database
do not effect one another.

You'll need lots of disk space to run the two environments with lots
of software installed and profiles but the profiles can be garbage
collected and you will have a very powerful software environment that
will be very difficult to break.
If you drop an update and for any reason the new version is a
regression, just roll back to the previous profile :

http://hydra.nixos.org/build/47813/download/1/manual/#sec-profiles

Hope some of that helps. :)

Thanks,
Tony