[Nix-dev] Proposal: Standard installation procedure

[Eelco Dolstra]

Hi,

On 22/10/14 11:55, Ertugrul Söylemez wrote:

> How would I refer to multiple systems with different configurations from
> within a Nix expression?  The change would allow this:
> 
>     { system1 = import <nixos/build-system.nix> module1;
>       system2 = import <nixos/build-system.nix> module2;
>       system3 = import <nixos/build-system.nix> module3; }

<nixpkgs/nixos> accepts a ‘configuration’ parameter, e.g.

  $ nix-build '<nixpkgs/nixos>' -A system --arg configuration \
    '{ fileSystems = ... ; services.httpd.enable = true; }'

You can also call <nixpkgs/nixos/lib/eval-config.nix>, which accepts an
arbitrary list of modules.

>> Programs like nixos-rebuild, nixos-install, nixos-container and even
>> NixOps are really just wrappers around this (except that they add
>> various levels of provisioning).
> 
> They all make the assumption that there is exactly one current system
> configuration.

NixOps builds/deploys multiple machines at the same time, so it can deal with an
arbitrary number of configurations.

-- 
Eelco Dolstra | LogicBlox, Inc. | http://nixos.org/~eelco/