gnu: Add CUPS service.

* gnu/services/cups.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add gnu/services/cups.scm.
* doc/guix.texi (Printing Services): New section.

doc/guix.texi

@@ -7643,6 +7643,7 @@ declaration.
 * Log Rotation::                The rottlog service.
 * Networking Services::         Network setup, SSH daemon, etc.
 * X Window::                    Graphical display.
+* Printing Services::           Local and remote printer support.
 * Desktop Services::            D-Bus and desktop services.
 * Database Services::           SQL databases.
 * Mail Services::               IMAP, POP3, SMTP, and all that.
@@ -8686,6 +8687,837 @@ makes the good ol' XlockMore usable.
 @end deffn
 
 
+@node Printing Services
+@subsubsection Printing Services
+
+The @code{(gnu services cups)} module provides a Guix service definition
+for the CUPS printing service.  To add printer support to a GuixSD
+system, add a @code{cups-service} to the operating system definition:
+
+@deffn {Scheme Variable} cups-service-type
+The service type for the CUPS print server.  Its value should be a valid
+CUPS configuration (see below).  For example:
+@example
+(service cups-service-type (cups-configuration))
+@end example
+@end deffn
+
+The CUPS configuration controls the basic things about your CUPS
+installation: what interfaces it listens on, what to do if a print job
+fails, how much logging to do, and so on.  To actually add a printer,
+you have to visit the @url{http://localhost:631} URL, or use a tool such
+as GNOME's printer configuration services.  By default, configuring a
+CUPS service will generate a self-signed certificate if needed, for
+secure connections to the print server.
+
+One way you might want to customize CUPS is to enable or disable the web
+interface.  You can do that directly, like this:
+
+@example
+(service cups-service-type
+         (cups-configuration
+           (web-interface? #f)))
+@end example
+
+The available configuration parameters follow.  Each parameter
+definition is preceded by its type; for example, @samp{string-list foo}
+indicates that the @code{foo} parameter should be specified as a list of
+strings.  There is also a way to specify the configuration as a string,
+if you have an old @code{cupsd.conf} file that you want to port over
+from some other system; see the end for more details.
+
+@c The following documentation was initially generated by
+@c (generate-documentation) in (gnu services cups).  Manually maintained
+@c documentation is better, so we shouldn't hesitate to edit below as
+@c needed.  However if the change you want to make to this documentation
+@c can be done in an automated way, it's probably easier to change
+@c (generate-documentation) than to make it below and have to deal with
+@c the churn as CUPS updates.
+
+
+Available @code{cups-configuration} fields are:
+
+@deftypevr {@code{cups-configuration} parameter} package cups
+The CUPS package.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} package-list extensions
+Drivers and other extensions to the CUPS package.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} files-configuration files-configuration
+Configuration of where to write logs, what directories to use for print
+spools, and related privileged configuration parameters.
+
+Available @code{files-configuration} fields are:
+
+@deftypevr {@code{files-configuration} parameter} log-location access-log
+Defines the access log filename.  Specifying a blank filename disables
+access log generation.  The value @code{stderr} causes log entries to be
+sent to the standard error file when the scheduler is running in the
+foreground, or to the system log daemon when run in the background.  The
+value @code{syslog} causes log entries to be sent to the system log
+daemon.  The server name may be included in filenames using the string
+@code{%s}, as in @code{/var/log/cups/%s-access_log}.
+
+Defaults to @samp{"/var/log/cups/access_log"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} file-name cache-dir
+Where CUPS should cache data.
+
+Defaults to @samp{"/var/cache/cups"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} string config-file-perm
+Specifies the permissions for all configuration files that the scheduler
+writes.
+
+Note that the permissions for the printers.conf file are currently
+masked to only allow access from the scheduler user (typically root).
+This is done because printer device URIs sometimes contain sensitive
+authentication information that should not be generally known on the
+system.  There is no way to disable this security feature.
+
+Defaults to @samp{"0640"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} log-location error-log
+Defines the error log filename.  Specifying a blank filename disables
+access log generation.  The value @code{stderr} causes log entries to be
+sent to the standard error file when the scheduler is running in the
+foreground, or to the system log daemon when run in the background.  The
+value @code{syslog} causes log entries to be sent to the system log
+daemon.  The server name may be included in filenames using the string
+@code{%s}, as in @code{/var/log/cups/%s-error_log}.
+
+Defaults to @samp{"/var/log/cups/error_log"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} string fatal-errors
+Specifies which errors are fatal, causing the scheduler to exit.  The
+kind strings are:
+
+@table @code
+@item none
+No errors are fatal.
+
+@item all
+All of the errors below are fatal.
+
+@item browse
+Browsing initialization errors are fatal, for example failed connections
+to the DNS-SD daemon.
+
+@item config
+Configuration file syntax errors are fatal.
+
+@item listen
+Listen or Port errors are fatal, except for IPv6 failures on the
+loopback or @code{any} addresses.
+
+@item log
+Log file creation or write errors are fatal.
+
+@item permissions
+Bad startup file permissions are fatal, for example shared TLS
+certificate and key files with world-read permissions.
+@end table
+
+Defaults to @samp{"all -browse"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} boolean file-device?
+Specifies whether the file pseudo-device can be used for new printer
+queues.  The URI @uref{file:///dev/null} is always allowed.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} string group
+Specifies the group name or ID that will be used when executing external
+programs.
+
+Defaults to @samp{"lp"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} string log-file-perm
+Specifies the permissions for all log files that the scheduler writes.
+
+Defaults to @samp{"0644"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} log-location page-log
+Defines the page log filename.  Specifying a blank filename disables
+access log generation.  The value @code{stderr} causes log entries to be
+sent to the standard error file when the scheduler is running in the
+foreground, or to the system log daemon when run in the background.  The
+value @code{syslog} causes log entries to be sent to the system log
+daemon.  The server name may be included in filenames using the string
+@code{%s}, as in @code{/var/log/cups/%s-page_log}.
+
+Defaults to @samp{"/var/log/cups/page_log"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} string remote-root
+Specifies the username that is associated with unauthenticated accesses
+by clients claiming to be the root user.  The default is @code{remroot}.
+
+Defaults to @samp{"remroot"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} file-name request-root
+Specifies the directory that contains print jobs and other HTTP request
+data.
+
+Defaults to @samp{"/var/spool/cups"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} sandboxing sandboxing
+Specifies the level of security sandboxing that is applied to print
+filters, backends, and other child processes of the scheduler; either
+@code{relaxed} or @code{strict}.  This directive is currently only
+used/supported on macOS.
+
+Defaults to @samp{strict}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} file-name server-keychain
+Specifies the location of TLS certificates and private keys.  CUPS will
+look for public and private keys in this directory: a @code{.crt} files
+for PEM-encoded certificates and corresponding @code{.key} files for
+PEM-encoded private keys.
+
+Defaults to @samp{"/etc/cups/ssl"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} file-name server-root
+Specifies the directory containing the server configuration files.
+
+Defaults to @samp{"/etc/cups"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} boolean sync-on-close?
+Specifies whether the scheduler calls fsync(2) after writing
+configuration or state files.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} space-separated-string-list system-group
+Specifies the group(s) to use for @code{@@SYSTEM} group authentication.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} file-name temp-dir
+Specifies the directory where temporary files are stored.
+
+Defaults to @samp{"/var/spool/cups/tmp"}.
+@end deftypevr
+
+@deftypevr {@code{files-configuration} parameter} string user
+Specifies the user name or ID that is used when running external
+programs.
+
+Defaults to @samp{"lp"}.
+@end deftypevr
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} access-log-level access-log-level
+Specifies the logging level for the AccessLog file.  The @code{config}
+level logs when printers and classes are added, deleted, or modified and
+when configuration files are accessed or updated.  The @code{actions}
+level logs when print jobs are submitted, held, released, modified, or
+canceled, and any of the conditions for @code{config}.  The @code{all}
+level logs all requests.
+
+Defaults to @samp{actions}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} boolean auto-purge-jobs?
+Specifies whether to purge job history data automatically when it is no
+longer required for quotas.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} browse-local-protocols browse-local-protocols
+Specifies which protocols to use for local printer sharing.
+
+Defaults to @samp{dnssd}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} boolean browse-web-if?
+Specifies whether the CUPS web interface is advertised.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} boolean browsing?
+Specifies whether shared printers are advertised.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} string classification
+Specifies the security classification of the server.  Any valid banner
+name can be used, including "classified", "confidential", "secret",
+"topsecret", and "unclassified", or the banner can be omitted to disable
+secure printing functions.
+
+Defaults to @samp{""}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} boolean classify-override?
+Specifies whether users may override the classification (cover page) of
+individual print jobs using the @code{job-sheets} option.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} default-auth-type default-auth-type
+Specifies the default type of authentication to use.
+
+Defaults to @samp{Basic}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} default-encryption default-encryption
+Specifies whether encryption will be used for authenticated requests.
+
+Defaults to @samp{Required}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} string default-language
+Specifies the default language to use for text and web content.
+
+Defaults to @samp{"en"}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} string default-paper-size
+Specifies the default paper size for new print queues.  @samp{"Auto"}
+uses a locale-specific default, while @samp{"None"} specifies there is
+no default paper size.  Specific size names are typically
+@samp{"Letter"} or @samp{"A4"}.
+
+Defaults to @samp{"Auto"}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} string default-policy
+Specifies the default access policy to use.
+
+Defaults to @samp{"default"}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} boolean default-shared?
+Specifies whether local printers are shared by default.
+
+Defaults to @samp{#t}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer dirty-clean-interval
+Specifies the delay for updating of configuration and state files, in
+seconds.  A value of 0 causes the update to happen as soon as possible,
+typically within a few milliseconds.
+
+Defaults to @samp{30}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} error-policy error-policy
+Specifies what to do when an error occurs.  Possible values are
+@code{abort-job}, which will discard the failed print job;
+@code{retry-job}, which will retry the job at a later time;
+@code{retry-this-job}, which retries the failed job immediately; and
+@code{stop-printer}, which stops the printer.
+
+Defaults to @samp{stop-printer}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer filter-limit
+Specifies the maximum cost of filters that are run concurrently, which
+can be used to minimize disk, memory, and CPU resource problems.  A
+limit of 0 disables filter limiting.  An average print to a
+non-PostScript printer needs a filter limit of about 200.  A PostScript
+printer needs about half that (100).  Setting the limit below these
+thresholds will effectively limit the scheduler to printing a single job
+at any time.
+
+Defaults to @samp{0}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer filter-nice
+Specifies the scheduling priority of filters that are run to print a
+job.  The nice value ranges from 0, the highest priority, to 19, the
+lowest priority.
+
+Defaults to @samp{0}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} host-name-lookups host-name-lookups
+Specifies whether to do reverse lookups on connecting clients.  The
+@code{double} setting causes @code{cupsd} to verify that the hostname
+resolved from the address matches one of the addresses returned for that
+hostname.  Double lookups also prevent clients with unregistered
+addresses from connecting to your server.  Only set this option to
+@code{#t} or @code{double} if absolutely required.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer job-kill-delay
+Specifies the number of seconds to wait before killing the filters and
+backend associated with a canceled or held job.
+
+Defaults to @samp{30}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer job-retry-interval
+Specifies the interval between retries of jobs in seconds.  This is
+typically used for fax queues but can also be used with normal print
+queues whose error policy is @code{retry-job} or
+@code{retry-current-job}.
+
+Defaults to @samp{30}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer job-retry-limit
+Specifies the number of retries that are done for jobs.  This is
+typically used for fax queues but can also be used with normal print
+queues whose error policy is @code{retry-job} or
+@code{retry-current-job}.
+
+Defaults to @samp{5}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} boolean keep-alive?
+Specifies whether to support HTTP keep-alive connections.
+
+Defaults to @samp{#t}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer keep-alive-timeout
+Specifies how long an idle client connection remains open, in seconds.
+
+Defaults to @samp{30}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer limit-request-body
+Specifies the maximum size of print files, IPP requests, and HTML form
+data.  A limit of 0 disables the limit check.
+
+Defaults to @samp{0}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} multiline-string-list listen
+Listens on the specified interfaces for connections.  Valid values are
+of the form @var{address}:@var{port}, where @var{address} is either an
+IPv6 address enclosed in brackets, an IPv4 address, or @code{*} to
+indicate all addresses.  Values can also be file names of local UNIX
+domain sockets.  The Listen directive is similar to the Port directive
+but allows you to restrict access to specific interfaces or networks.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer listen-back-log
+Specifies the number of pending connections that will be allowed.  This
+normally only affects very busy servers that have reached the MaxClients
+limit, but can also be triggered by large numbers of simultaneous
+connections.  When the limit is reached, the operating system will
+refuse additional connections until the scheduler can accept the pending
+ones.
+
+Defaults to @samp{128}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} location-access-control-list location-access-controls
+Specifies a set of additional access controls.
+
+Available @code{location-access-controls} fields are:
+
+@deftypevr {@code{location-access-controls} parameter} file-name path
+Specifies the URI path to which the access control applies.
+@end deftypevr
+
+@deftypevr {@code{location-access-controls} parameter} access-control-list access-controls
+Access controls for all access to this path, in the same format as the
+@code{access-controls} of @code{operation-access-control}.
+
+Defaults to @samp{()}.
+@end deftypevr
+
+@deftypevr {@code{location-access-controls} parameter} method-access-control-list method-access-controls
+Access controls for method-specific access to this path.
+
+Defaults to @samp{()}.
+
+Available @code{method-access-controls} fields are:
+
+@deftypevr {@code{method-access-controls} parameter} boolean reverse?
+If @code{#t}, apply access controls to all methods except the listed
+methods.  Otherwise apply to only the listed methods.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
+@deftypevr {@code{method-access-controls} parameter} method-list methods
+Methods to which this access control applies.
+
+Defaults to @samp{()}.
+@end deftypevr
+
+@deftypevr {@code{method-access-controls} parameter} access-control-list access-controls
+Access control directives, as a list of strings.  Each string should be
+one directive, such as "Order allow,deny".
+
+Defaults to @samp{()}.
+@end deftypevr
+@end deftypevr
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer log-debug-history
+Specifies the number of debugging messages that are retained for logging
+if an error occurs in a print job.  Debug messages are logged regardless
+of the LogLevel setting.
+
+Defaults to @samp{100}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} log-level log-level
+Specifies the level of logging for the ErrorLog file.  The value
+@code{none} stops all logging while @code{debug2} logs everything.
+
+Defaults to @samp{info}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} log-time-format log-time-format
+Specifies the format of the date and time in the log files.  The value
+@code{standard} logs whole seconds while @code{usecs} logs microseconds.
+
+Defaults to @samp{standard}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer max-clients
+Specifies the maximum number of simultaneous clients that are allowed by
+the scheduler.
+
+Defaults to @samp{100}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer max-clients-per-host
+Specifies the maximum number of simultaneous clients that are allowed
+from a single address.
+
+Defaults to @samp{100}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer max-copies
+Specifies the maximum number of copies that a user can print of each
+job.
+
+Defaults to @samp{9999}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer max-hold-time
+Specifies the maximum time a job may remain in the @code{indefinite}
+hold state before it is canceled.  A value of 0 disables cancellation of
+held jobs.
+
+Defaults to @samp{0}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs
+Specifies the maximum number of simultaneous jobs that are allowed.  Set
+to 0 to allow an unlimited number of jobs.
+
+Defaults to @samp{500}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs-per-printer
+Specifies the maximum number of simultaneous jobs that are allowed per
+printer.  A value of 0 allows up to MaxJobs jobs per printer.
+
+Defaults to @samp{0}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer max-jobs-per-user
+Specifies the maximum number of simultaneous jobs that are allowed per
+user.  A value of 0 allows up to MaxJobs jobs per user.
+
+Defaults to @samp{0}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer max-job-time
+Specifies the maximum time a job may take to print before it is
+canceled, in seconds.  Set to 0 to disable cancellation of "stuck" jobs.
+
+Defaults to @samp{10800}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer max-log-size
+Specifies the maximum size of the log files before they are rotated, in
+bytes.  The value 0 disables log rotation.
+
+Defaults to @samp{1048576}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer multiple-operation-timeout
+Specifies the maximum amount of time to allow between files in a
+multiple file print job, in seconds.
+
+Defaults to @samp{300}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} string page-log-format
+Specifies the format of PageLog lines.  Sequences beginning with percent
+(@samp{%}) characters are replaced with the corresponding information,
+while all other characters are copied literally.  The following percent
+sequences are recognized:
+
+@table @samp
+@item %%
+insert a single percent character
+
+@item %@{name@}
+insert the value of the specified IPP attribute
+
+@item %C
+insert the number of copies for the current page
+
+@item %P
+insert the current page number
+
+@item %T
+insert the current date and time in common log format
+
+@item %j
+insert the job ID
+
+@item %p
+insert the printer name
+
+@item %u
+insert the username
+@end table
+
+A value of the empty string disables page logging.  The string @code{%p
+%u %j %T %P %C %@{job-billing@} %@{job-originating-host-name@}
+%@{job-name@} %@{media@} %@{sides@}} creates a page log with the
+standard items.
+
+Defaults to @samp{""}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} environment-variables environment-variables
+Passes the specified environment variable(s) to child processes; a list
+of strings.
+
+Defaults to @samp{()}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} policy-configuration-list policies
+Specifies named access control policies.
+
+Available @code{policy-configuration} fields are:
+
+@deftypevr {@code{policy-configuration} parameter} string name
+Name of the policy.
+@end deftypevr
+
+@deftypevr {@code{policy-configuration} parameter} string job-private-access
+Specifies an access list for a job's private values.  @code{@@ACL} maps
+to the printer's requesting-user-name-allowed or
+requesting-user-name-denied values.  @code{@@OWNER} maps to the job's
+owner.  @code{@@SYSTEM} maps to the groups listed for the
+@code{system-group} field of the @code{files-config} configuration,
+which is reified into the @code{cups-files.conf(5)} file.  Other
+possible elements of the access list include specific user names, and
+@code{@@@var{group}} to indicate members of a specific group.  The
+access list may also be simply @code{all} or @code{default}.
+
+Defaults to @samp{"@@OWNER @@SYSTEM"}.
+@end deftypevr
+
+@deftypevr {@code{policy-configuration} parameter} string job-private-values
+Specifies the list of job values to make private, or @code{all},
+@code{default}, or @code{none}.
+
+Defaults to @samp{"job-name job-originating-host-name
+job-originating-user-name phone"}.
+@end deftypevr
+
+@deftypevr {@code{policy-configuration} parameter} string subscription-private-access
+Specifies an access list for a subscription's private values.
+@code{@@ACL} maps to the printer's requesting-user-name-allowed or
+requesting-user-name-denied values.  @code{@@OWNER} maps to the job's
+owner.  @code{@@SYSTEM} maps to the groups listed for the
+@code{system-group} field of the @code{files-config} configuration,
+which is reified into the @code{cups-files.conf(5)} file.  Other
+possible elements of the access list include specific user names, and
+@code{@@@var{group}} to indicate members of a specific group.  The
+access list may also be simply @code{all} or @code{default}.
+
+Defaults to @samp{"@@OWNER @@SYSTEM"}.
+@end deftypevr
+
+@deftypevr {@code{policy-configuration} parameter} string subscription-private-values
+Specifies the list of job values to make private, or @code{all},
+@code{default}, or @code{none}.
+
+Defaults to @samp{"notify-events notify-pull-method notify-recipient-uri
+notify-subscriber-user-name notify-user-data"}.
+@end deftypevr
+
+@deftypevr {@code{policy-configuration} parameter} operation-access-control-list access-controls
+Access control by IPP operation.
+
+Defaults to @samp{()}.
+@end deftypevr
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} boolean-or-non-negative-integer preserve-job-files
+Specifies whether job files (documents) are preserved after a job is
+printed.  If a numeric value is specified, job files are preserved for
+the indicated number of seconds after printing.  Otherwise a boolean
+value applies indefinitely.
+
+Defaults to @samp{86400}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} boolean-or-non-negative-integer preserve-job-history
+Specifies whether the job history is preserved after a job is printed.
+If a numeric value is specified, the job history is preserved for the
+indicated number of seconds after printing.  If @code{#t}, the job
+history is preserved until the MaxJobs limit is reached.
+
+Defaults to @samp{#t}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer reload-timeout
+Specifies the amount of time to wait for job completion before
+restarting the scheduler.
+
+Defaults to @samp{30}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} string rip-cache
+Specifies the maximum amount of memory to use when converting documents
+into bitmaps for a printer.
+
+Defaults to @samp{"128m"}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} string server-admin
+Specifies the email address of the server administrator.
+
+Defaults to @samp{"root@@localhost.localdomain"}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} host-name-list-or-* server-alias
+The ServerAlias directive is used for HTTP Host header validation when
+clients connect to the scheduler from external interfaces.  Using the
+special name @code{*} can expose your system to known browser-based DNS
+rebinding attacks, even when accessing sites through a firewall.  If the
+auto-discovery of alternate names does not work, we recommend listing
+each alternate name with a ServerAlias directive instead of using
+@code{*}.
+
+Defaults to @samp{*}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} string server-name
+Specifies the fully-qualified host name of the server.
+
+Defaults to @samp{"localhost"}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} server-tokens server-tokens
+Specifies what information is included in the Server header of HTTP
+responses.  @code{None} disables the Server header.  @code{ProductOnly}
+reports @code{CUPS}.  @code{Major} reports @code{CUPS 2}.  @code{Minor}
+reports @code{CUPS 2.0}.  @code{Minimal} reports @code{CUPS 2.0.0}.
+@code{OS} reports @code{CUPS 2.0.0 (@var{uname})} where @var{uname} is
+the output of the @code{uname} command.  @code{Full} reports @code{CUPS
+2.0.0 (@var{uname}) IPP/2.0}.
+
+Defaults to @samp{Minimal}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} string set-env
+Set the specified environment variable to be passed to child processes.
+
+Defaults to @samp{"variable value"}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} multiline-string-list ssl-listen
+Listens on the specified interfaces for encrypted connections.  Valid
+values are of the form @var{address}:@var{port}, where @var{address} is
+either an IPv6 address enclosed in brackets, an IPv4 address, or
+@code{*} to indicate all addresses.
+
+Defaults to @samp{()}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} ssl-options ssl-options
+Sets encryption options.  By default, CUPS only supports encryption
+using TLS v1.0 or higher using known secure cipher suites.  The
+@code{AllowRC4} option enables the 128-bit RC4 cipher suites, which are
+required for some older clients that do not implement newer ones.  The
+@code{AllowSSL3} option enables SSL v3.0, which is required for some
+older clients that do not support TLS v1.0.
+
+Defaults to @samp{()}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} boolean strict-conformance?
+Specifies whether the scheduler requires clients to strictly adhere to
+the IPP specifications.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} non-negative-integer timeout
+Specifies the HTTP request timeout, in seconds.
+
+Defaults to @samp{300}.
+
+@end deftypevr
+
+@deftypevr {@code{cups-configuration} parameter} boolean web-interface?
+Specifies whether the web interface is enabled.
+
+Defaults to @samp{#f}.
+@end deftypevr
+
+At this point you're probably thinking ``oh dear, Guix manual, I like
+you but you can stop already with the configuration options''.  Indeed.
+However, one more point: it could be that you have an existing
+@code{cupsd.conf} that you want to use.  In that case, you can pass an
+@code{opaque-cups-configuration} as the configuration of a
+@code{cups-service-type}.
+
+Available @code{opaque-cups-configuration} fields are:
+
+@deftypevr {@code{opaque-cups-configuration} parameter} package cups
+The CUPS package.
+@end deftypevr
+
+@deftypevr {@code{opaque-cups-configuration} parameter} string cupsd.conf
+The contents of the @code{cupsd.conf}, as a string.
+@end deftypevr
+
+@deftypevr {@code{opaque-cups-configuration} parameter} string cups-files.conf
+The contents of the @code{cups-files.conf} file, as a string.
+@end deftypevr
+
+For example, if your @code{cupsd.conf} and @code{cups-files.conf} are in
+strings of the same name, you could instantiate a CUPS service like
+this:
+
+@example
+(service cups-service-type
+         (opaque-cups-configuration
+           (cupsd.conf cupsd.conf)
+           (cups-files.conf cups-files.conf)))
+@end example
+
+
 @node Desktop Services
 @subsubsection Desktop Services
 

gnu/local.mk

@@ -391,6 +391,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/services/admin.scm			\
   %D%/services/avahi.scm			\
   %D%/services/base.scm				\
+  %D%/services/cups.scm				\
   %D%/services/databases.scm			\
   %D%/services/dbus.scm				\
   %D%/services/desktop.scm			\