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authorLudovic Courtès <ludo@gnu.org>2015-05-08 14:59:00 +0200
committerLudovic Courtès <ludo@gnu.org>2015-05-08 16:35:32 +0200
commit15137a29c23e4beab7641b6c6191fdff9716dea4 (patch)
tree0bbe0f45d3c5c2970d12a7ef75b457bcc053fecf
parent6b888efff627c0e50f45e22a6408a02232d3b87f (diff)
downloadguix-15137a29c23e4beab7641b6c6191fdff9716dea4.tar
guix-15137a29c23e4beab7641b6c6191fdff9716dea4.tar.gz
nss: Add '%mdns-host-lookup-nss'.
* gnu/system/nss.scm (%mdns-host-lookup-nss): New variable. * doc/guix.texi (Name Service Switch): Document it.
-rw-r--r--doc/guix.texi24
-rw-r--r--gnu/system/nss.scm23
2 files changed, 42 insertions, 5 deletions
diff --git a/doc/guix.texi b/doc/guix.texi
index 2d02a04f9c..8e36ce3a5c 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -5180,6 +5180,10 @@ for host names ending in @code{.local}:
(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}
@@ -5207,6 +5211,21 @@ configuration file:
@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
@@ -5217,11 +5236,6 @@ not only of adding this warm parenthetic feel that we like, but also
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
diff --git a/gnu/system/nss.scm b/gnu/system/nss.scm
index ec2d2517e7..f4d2855289 100644
--- a/gnu/system/nss.scm
+++ b/gnu/system/nss.scm
@@ -29,6 +29,8 @@
lookup-specification
%default-nss
+ %mdns-host-lookup-nss
+
%files
%compat
%dns
@@ -148,6 +150,27 @@
;; 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"))))))
+
;;;
;;; Serialization.