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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/guix.texi | 73 |
1 files changed, 67 insertions, 6 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index 0a3827911b..01e28041f2 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -5363,16 +5363,40 @@ The @code{services} field lists @dfn{system services} to be made available when the system starts (@pxref{Services}). The @code{operating-system} declaration above specifies that, in addition to the basic services, we want the @command{lshd} secure shell -daemon listening on port 2222, and allowing remote @code{root} logins -(@pxref{Invoking lshd,,, lsh, GNU lsh Manual}). Under the hood, +daemon listening on port 2222 (@pxref{Networking Services, +@code{lsh-service}}). Under the hood, @code{lsh-service} arranges so that @code{lshd} is started with the right command-line options, possibly with supporting configuration files -generated as needed (@pxref{Defining Services}). @xref{operating-system -Reference}, for details about the available @code{operating-system} -fields. +generated as needed (@pxref{Defining Services}). + +@cindex customization, of services +@findex modify-services +Occasionally, instead of using the base services as is, you will want to +customize them. For instance, to change the configuration of +@code{guix-daemon} and Mingetty (the console log-in), you may write the +following instead of @var{%base-services}: + +@lisp +(modify-services %base-services + (guix-service-type config => + (guix-configuration + (inherit config) + (use-substitutes? #f) + (extra-options '("--gc-keep-outputs")))) + (mingetty-service-type config => + (mingetty-configuration + (inherit config) + (motd (plain-file "motd" "Hi there!"))))) +@end lisp + +@noindent +The effect here is to change the options passed to @command{guix-daemon} +when it is started, as well as the ``message of the day'' that appears +when logging in at the console. @xref{Service Reference, +@code{modify-services}}, for more on that. The configuration for a typical ``desktop'' usage, with the X11 display -server, a desktop environment, network management, an SSH server, and +server, a desktop environment, network management, power management, and more, would look like this: @lisp @@ -5382,6 +5406,8 @@ more, would look like this: @xref{Desktop Services}, for the exact list of services provided by @var{%desktop-services}. @xref{X.509 Certificates}, for background information about the @code{nss-certs} package that is used here. +@xref{operating-system Reference}, for details about all the available +@code{operating-system} fields. Assuming the above snippet is stored in the @file{my-system-config.scm} file, the @command{guix system reconfigure my-system-config.scm} command @@ -7539,6 +7565,41 @@ Here is an example of how a service is created and manipulated: @result{} #t @end example +The @code{modify-services} form provides a handy way to change the +parameters of some of the services of a list such as +@var{%base-services} (@pxref{Base Services, @code{%base-services}}). Of +course, you could always use standard list combinators such as +@code{map} and @code{fold} to do that (@pxref{SRFI-1, List Library,, +guile, GNU Guile Reference Manual}); @code{modify-services} simply +provides a more concise form for this common pattern. + +@deffn {Scheme Syntax} modify-services @var{services} @ + (@var{type} @var{variable} => @var{body}) @dots{} + +Modify the services listed in @var{services} according to the given +clauses. Each clause has the form: + +@example +(@var{type} @var{variable} => @var{body}) +@end example + +where @var{type} is a service type, such as @var{guix-service-type}, and +@var{variable} is an identifier that is bound within @var{body} to the +value of the service of that @var{type}. @xref{Using the Configuration +System}, for an example. + +This is a shorthand for: + +@example +(map (lambda (service) @dots{}) @var{services}) +@end example +@end deffn + +Next comes the programming interface for service types. This is +something you want to know when writing new service definitions, but not +necessarily when simply looking for ways to customize your +@code{operating-system} declaration. + @deftp {Data Type} service-type @cindex service type This is the representation of a @dfn{service type} (@pxref{Service Types |