Configuration System's Handling of Missing Packages

Configuration System's Handling of Missing Packages

[Keith Osterheld]

Hi,

How does the configuration system handle references to packages that
aren't installed? For example, if I add (use-package-modules xfce) to my config file
but I don't have xfce installed, will guix automatically install it, or
will it throw errors?

Keith

Re: Configuration System's Handling of Missing Packages

[Efraim Flashner]

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On Wed, 23 Dec 2015 21:08:40 -0800
Keith Osterheld <keitho@openmailbox.org> wrote:

> Hi,
> 
> How does the configuration system handle references to packages that
> aren't installed? For example, if I add (use-package-modules xfce) to my config file
> but I don't have xfce installed, will guix automatically install it, or
> will it throw errors?
> 
> Keith
> 

If you don't add (use-package-modules xfce) at the top of your config and you
don't use it in (packages ...) then it won't be added.

On the other hand, if you added had (packages (cons* xfce ...)) but didn't
have (use-package-modules xfce) then it would throw an error.

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Re: Configuration System's Handling of Missing Packages

[宋文武]

Keith Osterheld <keitho@openmailbox.org> writes:

> Hi,
>
> How does the configuration system handle references to packages that
> aren't installed? For example, if I add (use-package-modules xfce) to my config file
> but I don't have xfce installed, will guix automatically install it, or
> will it throw errors?
“(use-package-modules xfce)” is same as “(use-modules gnu packages xfce)”,
it only make the ‘xfce’ module avaliable (like ‘import’ or ‘require’),
but to actually use the 'xfce' package (exported by the ‘xfce’ module),
you need to add it to the ‘packages’ field of the ‘operating-system’.

items (packages, configuration files, etc) will be download or build
into the ’/gnu’ store when building the ’operating-system’, and packages
listed in the ‘packages’ field will be “installed” into the system
profile, aka ’/run/current-system/profile’.

so, the anwser is “Yes, Guix will install it automatically”.
Errors will be reported if a invalid configuration is used,
It’s a scheme file, so syntax and runtime errors may be common :-)

Re: Configuration System's Handling of Missing Packages

[Keith Osterheld]

Thanks for the help! I have another question now.

> “(use-package-modules xfce)” is same as “(use-modules gnu packages xfce)”,
> it only make the ‘xfce’ module avaliable (like ‘import’ or ‘require’),
> but to actually use the 'xfce' package (exported by the ‘xfce’ module),
> you need to add it to the ‘packages’ field of the ‘operating-system’.
>
> items (packages, configuration files, etc) will be download or build
> into the ’/gnu’ store when building the ’operating-system’, and packages
> listed in the ‘packages’ field will be “installed” into the system
> profile, aka ’/run/current-system/profile’.

What's the difference between a package being downloaded into /gnu
instead of the system profile, and when should I use the package module
instead of installing it normally? To me it seems like the only reason
for using a package module is for easier deployment, is that right?

Thanks,
Keith

Re: Configuration System's Handling of Missing Packages

[Ricardo Wurmus]

Keith Osterheld <keitho@openmailbox.org> writes:

> What's the difference between a package being downloaded into /gnu
> instead of the system profile, and when should I use the package module
> instead of installing it normally? To me it seems like the only reason
> for using a package module is for easier deployment, is that right?

*Every* package is installed into /gnu.  Profile generations, too, have
their own directory somewhere in /gnu.  They are *also* linked
elsewhere, such as ~/.guix-profile or the system profile.  When a
package is installed it is first built or downloaded into some place in
/gnu/store, and then a new profile generation in /gnu/store is created,
which contains a link to the new package.

Package modules have nothing to do with package installation.  All
packages in Guix are Scheme expressions bound to names.  These bindings
are *defined* in modules.  If you want to refer to any package
expression by name in a programme or another expression (such as the
system configuration or a manifest) you have to make sure that the
module is loaded in the current file.

~~ Ricardo