NAME

       policy-rc.d-declarative - define system service policies declaratively

SYNOPSIS

       policy-rc.d

DESCRIPTION

       Debian policy states that packages providing system services need to start those services by default, and
       that the starting of the service should be done by way of the /usr/sbin/invoke-rc.d script. This script
       will execute a program /usr/sbin/policy-rc.d if it exists, allowing the local system administrator to
       override behaviour if wanted by creating a policy script according to the interface specified and
       installing it as /usr/sbin/policy-rc.d.

       This interface, however, has some downsides:

       •   While  the  definition of the policy-rc.d interface specifies that policy scripts should be installed
           by way of the alternatives system, there are various cases (e.g., the initial installation of  Debian
           from  the  Debian  installer)  where  installing a policy script is desirable before the alternatives
           system is available for use. The result is that the installer creates a  policy-rc.d  script  without
           going  through  the alternatives system, which it then removes at the end of the installation. A side
           effect of this is that any creation of a policy script in the installer will be blown away at the end
           of an installation.

           As a result of this, at least one derivative distribution believed  they  were  installing  a  policy
           script into all their installations when in fact they weren't.

       •   Because  the  default  state  is  for  there  to be no policy script on the system, the fact that the
           interface exists in the first place is something that is unknown  to  many  long-time  Debian  users.
           Having  something that can be configured through a (set of) configuration files in /etc instead makes
           the system discoverable, and allows for better documentation of the interface.

       Moreover, a scripted interface is far more powerful than necessary; in most cases, all that is needed  is
       a default policy for all services, which does not require a turing-complete language.

       This  policy  script  attempts  to  solve  these issues by allowing system administrators to provide init
       script policies by way of a declarative interface, rather than a scripted one. It does this by way  of  a
       directory /etc/service-policy.d in which packages and/or system administrators may place files describing
       the  policy  to be followed. For more information on how these files should be structured, please see the
       service-policy.d(5) man page.

BUGS

       The policy script interface definition states that policy scripts must  support  "--quiet"  and  "--list"
       arguments. This policy script does not (yet) implement those.

       The  list  of allowed actions may be somewhat small at present. Future versions of this policy script are
       likely to add more, or to add a way to create custom actions. Wishlist bugs (or patches) welcome!

       The policy script interface also specifies a runlevel argument to the script. This policy script does not
       currently use or read that argument, because it is believed to be not helpful. This  may  change  in  the
       future.

SEE ALSO

       /usr/share/doc/init-system-helpers/README.policy-rc.d.gz, invoke-rc.d(8), service-policy.d(5)

                                                   2020-11-23                         POLICY-RC.D-DECLARATIVE(8)