diff options
| -rw-r--r-- | doc/guix.texi | 85 | ||||
| -rw-r--r-- | gnu/services/base.scm | 121 |
2 files changed, 200 insertions, 6 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index bb52cf713f..00737850fd 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -4177,10 +4177,91 @@ tool suite.) the ``message of the day''. @end deffn -@deffn {Monadic Procedure} nscd-service [#:glibc glibc] -Return a service that runs libc's name service cache daemon (nscd). +@cindex name service cache daemon +@cindex nscd +@deffn {Monadic Procedure} nscd-service [@var{config}] [#:glibc glibc] +Return a service that runs libc's name service cache daemon (nscd) with the +given @var{config}---an @code{<nscd-configuration>} object. @end deffn +@defvr {Scheme Variable} %nscd-default-configuration +This is the default @code{<nscd-configuration>} value (see below) used +by @code{nscd-service}. This uses the caches defined by +@var{%nscd-default-caches}; see below. +@end defvr + +@deftp {Data Type} nscd-configuration +This is the type representing the name service cache daemon (nscd) +configuration. + +@table @asis + +@item @code{log-file} (default: @code{"/var/log/nscd.log"}) +Name of nscd's log file. This is where debugging output goes when +@code{debug-level} is strictly positive. + +@item @code{debug-level} (default: @code{0}) +Integer denoting the debugging levels. Higher numbers mean more +debugging output is logged. + +@item @code{caches} (default: @var{%nscd-default-caches}) +List of @code{<nscd-cache>} objects denoting things to be cached; see +below. + +@end table +@end deftp + +@deftp {Data Type} nscd-cache +Data type representing a cache database of nscd and its parameters. + +@table @asis + +@item @code{database} +This is a symbol representing the name of the database to be cached. +Valid values are @code{passwd}, @code{group}, @code{hosts}, and +@code{services}, which designate the corresponding NSS database +(@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}). + +@item @code{positive-time-to-live} +@itemx @code{negative-time-to-live} (default: @code{20}) +A number representing the number of seconds during which a positive or +negative lookup result remains in cache. + +@item @code{check-files?} (default: @code{#t}) +Whether to check for updates of the files corresponding to +@var{database}. + +For instance, when @var{database} is @code{hosts}, setting this flag +instructs nscd to check for updates in @file{/etc/hosts} and to take +them into account. + +@item @code{persistent?} (default: @code{#t}) +Whether the cache should be stored persistently on disk. + +@item @code{shared?} (default: @code{#t}) +Whether the cache should be shared among users. + +@item @code{max-database-size} (default: 32@tie{}MiB) +Maximum size in bytes of the database cache. + +@c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert +@c settings, so leave them out. + +@end table +@end deftp + +@defvr {Scheme Variable} %nscd-default-caches +List of @code{<nscd-cache>} objects used by default by +@code{nscd-configuration} (see above.) + +It enables persistent and aggressive caching of service and host name +lookups. The latter provides better host name lookup performance, +resilience in the face of unreliable name servers, and also better +privacy---often the result of host name lookups is in local cache, so +external name servers do not even need to be queried. +@end defvr + + @deffn {Monadic Procedure} syslog-service Return a service that runs @code{syslogd} with reasonable default settings. diff --git a/gnu/services/base.scm b/gnu/services/base.scm index 712222bdde..95edba6e7c 100644 --- a/gnu/services/base.scm +++ b/gnu/services/base.scm @@ -33,8 +33,10 @@ #:select (mount-flags->bit-mask)) #:use-module (guix gexp) #:use-module (guix monads) + #:use-module (guix records) #:use-module (srfi srfi-1) #:use-module (srfi srfi-26) + #:use-module (ice-9 match) #:use-module (ice-9 format) #:export (root-file-system-service file-system-service @@ -46,6 +48,16 @@ console-font-service udev-service mingetty-service + + %nscd-default-caches + %nscd-default-configuration + + nscd-configuration + nscd-configuration? + + nscd-cache + nscd-cache? + nscd-service syslog-service guix-service @@ -374,9 +386,110 @@ the ``message of the day''." #:allow-empty-passwords? allow-empty-passwords? #:motd motd))))))) -(define* (nscd-service #:key (glibc (canonical-package glibc))) - "Return a service that runs libc's name service cache daemon (nscd)." - (with-monad %store-monad +(define-record-type* <nscd-configuration> nscd-configuration + make-nscd-configuration + nscd-configuration? + (log-file nscd-configuration-log-file ;string + (default "/var/log/nscd.log")) + (debug-level nscd-debug-level ;integer + (default 0)) + ;; TODO: See nscd.conf in glibc for other options to add. + (caches nscd-configuration-caches ;list of <nscd-cache> + (default %nscd-default-caches))) + +(define-record-type* <nscd-cache> nscd-cache make-nscd-cache + nscd-cache? + (database nscd-cache-database) ;symbol + (positive-time-to-live nscd-cache-positive-time-to-live) ;integer + (negative-time-to-live nscd-cache-negative-time-to-live + (default 20)) ;integer + (suggested-size nscd-cache-suggested-size ;integer ("default module + ;of hash table") + (default 211)) + (check-files? nscd-cache-check-files? ;Boolean + (default #t)) + (persistent? nscd-cache-persistent? ;Boolean + (default #t)) + (shared? nscd-cache-shared? ;Boolean + (default #t)) + (max-database-size nscd-cache-max-database-size ;integer + (default (* 32 (expt 2 20)))) + (auto-propagate? nscd-cache-auto-propagate? ;Boolean + (default #t))) + +(define %nscd-default-caches + ;; Caches that we want to enable by default. Note that when providing an + ;; empty nscd.conf, all caches are disabled. + (list (nscd-cache (database 'hosts) + + ;; Aggressively cache the host name cache to improve + ;; privacy and resilience. + (positive-time-to-live (* 3600 12)) + (negative-time-to-live 20) + (persistent? #t)) + + (nscd-cache (database 'services) + + ;; Services are unlikely to change, so we can be even more + ;; aggressive. + (positive-time-to-live (* 3600 24)) + (negative-time-to-live 3600) + (check-files? #t) ;check /etc/services changes + (persistent? #t)))) + +(define %nscd-default-configuration + ;; Default nscd configuration. + (nscd-configuration)) + +(define (nscd.conf-file config) + "Return the @file{nscd.conf} configuration file for @var{config}, an +@code{<nscd-configuration>} object." + (define cache->config + (match-lambda + (($ <nscd-cache> (= symbol->string database) + positive-ttl negative-ttl size check-files? + persistent? shared? max-size propagate?) + (string-append "\nenable-cache\t" database "\tyes\n" + + "positive-time-to-live\t" database "\t" + (number->string positive-ttl) "\n" + "negative-time-to-live\t" database "\t" + (number->string negative-ttl) "\n" + "suggested-size\t" database "\t" + (number->string size) "\n" + "check-files\t" database "\t" + (if check-files? "yes\n" "no\n") + "persistent\t" database "\t" + (if persistent? "yes\n" "no\n") + "shared\t" database "\t" + (if shared? "yes\n" "no\n") + "max-db-size\t" database "\t" + (number->string max-size) "\n" + "auto-propagate\t" database "\t" + (if propagate? "yes\n" "no\n"))))) + + (match config + (($ <nscd-configuration> log-file debug-level caches) + (text-file "nscd.conf" + (string-append "\ +# Configuration of libc's name service cache daemon (nscd).\n\n" + (if log-file + (string-append "logfile\t" log-file) + "") + "\n" + (if debug-level + (string-append "debug-level\t" + (number->string debug-level)) + "") + "\n" + (string-concatenate + (map cache->config caches))))))) + +(define* (nscd-service #:optional (config %nscd-default-configuration) + #:key (glibc (canonical-package glibc))) + "Return a service that runs libc's name service cache daemon (nscd) with the +given @var{config}---an @code{<nscd-configuration>} object." + (mlet %store-monad ((nscd.conf (nscd.conf-file config))) (return (service (documentation "Run libc's name service cache daemon (nscd).") (provision '(nscd)) @@ -388,7 +501,7 @@ the ``message of the day''." (start #~(make-forkexec-constructor (list (string-append #$glibc "/sbin/nscd") - "-f" "/dev/null" "--foreground"))) + "-f" #$nscd.conf "--foreground"))) (stop #~(make-kill-destructor)) (respawn? #f))))) |