INVOKE-RUN(8)

NAME
invoke-run - runscript interpreter

SYNOPSIS
/usr/bin/env /lib/run/invoke-run

DESCRIPTION
The runit supervision system uses scripts, called runscripts to start services. By convention, runscript for a service foo is located at /etc/sv/foo/run

Debhelper addon dh_runit installs runscript according this convention.

Runscript can be any executable file. Runscript can use invoke-run interpreter only if it is installed according convention,

To use invoke-run interpreter, runscript /etc/sv/foo/run for service foo must begin with following line:

        #!/usr/bin/env /lib/runit/invoke-run

If the script /usr/sbin/policy-rc.d exists the policy layer is checked (see below). If init.d script /etc/init.d/foo exists, it is invoked with stop argument to gracefully handle package upgrade to version, introducing runscript. After that, /bin/sh shell interpret rest of runscript, with some additional environment set according following rules:

    A NAME=foo variable is exported.

    The /etc/default/runit file is interpreted with /bin/sh and all variable assignment are accessible to runscript.

    If file /etc/default/foo exists, it is interpreted with /bin/sh and all variable assignment are accessible to runscript.

    If directory /etc/sv/foo/conf exists, variables are set according to rules, documented in envdir section of chpst(8) manual.

If both /etc/default/foo file and /etc/sv/foo/conf directory define some variable, value from directory takes precedence.

SPECIAL ERROR CODE
Looking in the foo service log it's possible to see messages in the form of

    invoke-run: ERROR [NNN] in foo: reason for the error

These messages don't come from runsv itself but from invoke-run, the run file or the finish file. The purpose of these message is to detail a permanent failure condition that prevents foo service from being up. For each foo service, possible errors and messages are:

    invoke-run: foo binary not installed

    this happens when the package containing foo binary has been removed, but not purged.

    invoke-run: ERROR -1 in foo: runscript didn't exit normally

    this message comes from the finish file, but the exit code comes from runsv(8) and is documented in its manpage.

    invoke-run: WARNING for foo: disabled by local settings

    Some service specific setting prevent foo from starting; it's likely something in /etc/default/foo

    invoke-run: ERROR 162 in foo: configtest or early setup failed

    A configuration file of foo is malformed and the configtest failed; foo log may contain additional info from the test itself. Alternatively the runscript has failed to do some setup that is essential to the foo service.

    invoke-run: ERROR 170 in foo: a runtime hard dependency is missing

    A dependency failed the check and can't be bring up; to know dependencies of foo service look for "sv start" in "run" script.

FINISH FILE AND FINISH-DEFAULT
Since version 2.1.2-36 the Debian runit package ships a /lib/runit/finish-default file that contains code that can be shared across different services. This file can be sourced inside the regular finish file of a service, like the following example

     $ cat /etc/sv/foo/finish
     #!/bin/sh
     set -e
     . /lib/runit/finish-default "$@"

Services that need to put specific code into the finish file should do after the line that sources finish-default. For each foo service, finish-default file sources /etc/default/runit, export a NAME=foo variable and defines special error codes as described in the previous section. Also, when VERBOSE mode is on, EXIT is trapped so that a 'foo stopped' message gets printed at the very end of the finish file.

POLICY-RC.D LAYER
Since version 2.1.2-41 invoke-run support the policy-rc.d hack. When the /usr/sbin/policy-rc.d script exists, for each service invoke-run calls '/usr/sbin/policy-rc.d service' and check the return code. On 101 it sets the wanted status for the service as down and exits immediately. Any other return code is ignored and invoke-run will proceed with starting the service. The main use case for the policy-rc.d hack is for the Debian Installer to prevent services to start in chroot during the installation process; however in the past the hack was used also by local admins to perform custom actions. Local admin that want to use the policy-rc.d layer should be aware that with runit the hack prevents the service to start under any condition, including during the boot sequence. This is different from other init systems like systemd or sysv, where the hack only prevents services to start when invoked via maintscripts.

SEE ALSO
runsvdir(8), dh_runit(1), chpst(8)