(name "mdns")))))
@end example
+Don't worry: the @code{%mdns-host-lookup-nss} variable (see below)
+contains this configuration, so you won't have to type it if all you
+want is to have @code{.local} host lookup working.
+
Note that, in this case, in addition to setting the
@code{name-service-switch} of the @code{operating-system} declaration,
@code{nscd-service} must be told where to find the @code{nss-mdns}
@noindent
@dots{} and then refer to @var{%my-base-services} instead of
@var{%base-services} in the @code{operating-system} declaration.
+Lastly, this relies on the availability of the Avahi service
+(@pxref{Desktop Services, @code{avahi-service}}).
+
+For convenience, the following variables provide typical NSS
+configurations.
+
+@defvr {Scheme Variable} %default-nss
+This is the default name service switch configuration, a
+@code{name-service-switch} object.
+@end defvr
+
+@defvr {Scheme Variable} %mdns-host-lookup-nss
+This is the name service switch configuration with support for host name
+lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
+@end defvr
The reference for name service switch configuration is given below. It
is a direct mapping of the C library's configuration file format, so
static checks: you'll know about syntax errors and typos as soon as you
run @command{guix system}.
-@defvr {Scheme Variable} %default-nss
-This is the default name service switch configuration, a
-@code{name-service-switch} object.
-@end defvr
-
@deftp {Data Type} name-service-switch
This is the data type representation the configuration of libc's name
lookup-specification
%default-nss
+ %mdns-host-lookup-nss
+
%files
%compat
%dns
;; Default NSS configuration.
(name-service-switch))
+(define %mdns-host-lookup-nss
+ (name-service-switch
+ (hosts (list %files ;first, check /etc/hosts
+
+ ;; If the above did not succeed, try with 'mdns_minimal'.
+ (name-service
+ (name "mdns_minimal")
+
+ ;; 'mdns_minimal' is authoritative for '.local'. When it
+ ;; returns "not found", no need to try the next methods.
+ (reaction (lookup-specification
+ (not-found => return))))
+
+ ;; Then fall back to DNS.
+ (name-service
+ (name "dns"))
+
+ ;; Finally, try with the "full" 'mdns'.
+ (name-service
+ (name "mdns"))))))
+
\f
;;;
;;; Serialization.