finit/doc/config/service-opts.md

Service Options
===============

The `run`, `task`, `tty`, `service` and `sysv` blocks take settings as
keys.  This section lists them with their limitations.

The name of a service, shown by the `initctl` tool, is the block title.
It defaults to the basename of the executable if the title is omitted:

    service sshd {
        command = "/usr/sbin/sshd -D"
    }

For multiple instances of a service, with the same name, add an
identifier after a colon to prevent Finit from replacing previous
instances:

    service ssdp:eth1 { command = "ssdpd eth1" }
    service ssdp:eth2 { command = "ssdpd eth2" }

The [`initctl`](../initctl.md) tool will list these two services as:

 - ssdp:eth1
 - ssdp:eth2

Conflicting services that must be prevented from starting, use the
`conflicts` key:

    service udevd { command = "udevd" }
    run mdev {
        runlevel  = "S"
        conflicts = { "udevd" }
        command   = "mdev -s"
    }

The list may name several, and an instance is named the same way it is
declared:

    service abc:1 { command = "abc 1" }
    service abc:2 { command = "abc 2" }
    service cde   { conflicts = { "abc:1", "abc:2" }  command = "cde" }

If a service should not be automatically started, set `manual-start`.
It can then be started at any time with `initctl start <service>`:

    service lldpd {
        manual-start = true
        command      = "/usr/sbin/lldpd -d"
    }

Other run/task/service settings are:

  * `capabilities` -- see the [Linux Capabilities](capabilities.md) section
  * `cgroup NAME {}` -- see the [Cgroups](cgroups.md) section
  * `envfile` -- see the [Service Environment](service-env.md) section
  * `log {}` -- see [Redirecting Output](logging.md#redirecting-output)
  * `tty` -- see [Controlling TTY](tty.md#controlling-tty-for-services)
  * `notify` -- see [Service Synchronization](service-sync.md)
  * `if` -- see [Conditional Execution](services.md#conditional-execution)
  * `type = "forking"` -- see description of the [service](services.md) block
  * a leading `-` on `command` -- see
    [Conditional Loading](services.md#conditional-loading)

Command Candidates
------------------

The `command` setting may list several candidates for the same
service, in which case Finit starts the first one it finds:

    service udevd {
        command = { "/lib/systemd/systemd-udevd", "-udevd" }
    }

A candidate that is not installed is skipped without a warning, that
is the point of listing more than one.  The leading `-` is read from
the candidate that wins, or from the last one when none are found, so
a block with a single command behaves as it always has.

The candidates are alternative spellings of one service, not a
fallback for a service that fails to start.  Finit chooses when the
.conf file is read and does not revisit the choice.

A [`tty`](tty.md) block takes the same list, where the candidates are
the getty to run:

    tty ttyAMA0 {
        command = { "/sbin/agetty -L ttyAMA0 115200 vt100",
                    "/sbin/getty -L 115200 /dev/ttyAMA0 vt100" }
    }

Provided Conditions
-------------------

A service always asserts `pid/<ident>` for itself, named after the
block title.  `provides` names conditions it asserts in addition to
that one:

    service syslogd:udev {
        if       = "udevd"
        provides = "pid/syslogd"
        command  = "syslogd -F"
    }

This is what lets variants of one service, picked apart by
[`if`](services.md#conditional-execution), share the barrier that
everything downstream waits for.  Each variant has its own title, so
each is its own service to `initctl`, while the condition they publish
stays the same.

Any namespace works, `pid/`, `usr/`, `service/`, since the point is
publishing a name existing configuration already waits on.  A value
without a namespace separator is not a condition and is rejected.  The
list holds at most four.

A provided condition is asserted and cleared with the service, exactly
like its own, so stopping the provider clears the barrier.

Two services cannot supply the same condition.  The second claim is
refused, with the owner named:

    finit.conf: second: provides condition <usr/barrier> already registered by service first, ignoring

The service itself still registers and runs, only the claim is
dropped.  Which one is "first" is .conf load order, so it follows the
file names, see [Files & Layout](files.md).

A real identity outranks a claim on it.  `provides = "pid/sshd"` in a
system that also runs a service titled `sshd` loses to that service,
because `pid/<ident>` is how Finit tracks the service itself.

`initctl cond dump` names the owner of every condition, which for a
provided one is the service that claimed it:

    $ initctl cond dump
    PID    IDENT         STATUS  CONDITION
    1234   syslogd:udev  on      <pid/syslogd>
    1234   syslogd:udev  on      <pid/syslogd:udev>

Duplicate Titles
----------------

The title is the service identity, so two blocks sharing a title in
one file are two declarations of one service.  The parser underneath
merges them without a word, leaving a single service holding a mix of
both, so Finit rejects the file and names the title:

    /etc/finit.d/hotplug.conf:12: found duplicate title 'udevd'

Nothing from a rejected file is loaded and the rest of the
configuration is unaffected.

The same title in *another* file is fine.  That is how a system .conf
is overridden, the later file wins, see [Files & Layout](files.md).

Two shapes need a single identity and used to be written as repeated
declarations.  One is a service with several candidate binaries, which
is now a [command list](#command-candidates).  The other is a service
gated differently per platform, e.g. a syslog daemon waiting for
whichever hotplug daemon the system happens to have.  For that one,
give each variant its own file, or keep them as one-liners in the
line-based format, which has no titles.  The [migration
guide](migration.md) works through it.

Restarting
----------

Services are automatically started, restarted, and stopped, depending
on the configuration and conditions.  Within the confines of that the
following settings are available:

  * `restart-max = NUM` -- number of times Finit tries to restart a
    crashing service, default: 10.  When this limit is reached the
    service is marked *crashed* and must be restarted manually with
    `initctl restart NAME`
  * `restart-sec = SEC` -- number of seconds before Finit tries to
    restart a crashing service.  The default is 2 seconds for the first
    half of `restart-max` attempts, then a back-off to 5 seconds -- with
    the default `restart-max` that is the first five retries.  The
    greater of this configured value and the back-off is used
  * `restart = "always"` -- no upper limit on the number of times Finit
    tries to restart a crashing service
  * `restart = "never"` -- do not restart on failures.  `false` is
    accepted as a synonym, and `true` selects the default policy
  * `respawn = true` -- bypasses the `restart` mechanism completely,
    allowing endless restarts.  Exiting is treated as normal work
    rather than failure, so the service is restarted at once instead of
    being counted and delayed.  This is how a `tty` behaves; it is not
    what `service` was designed for, so it is not the default
  * `remain-after-exit = true` -- for `run` and `task` only.  Prevents
    the task from re-running on runlevel re-entry and ensures the
    `exec-stop-post` script runs when the task is explicitly stopped or
    leaves its valid runlevels.  This is systemd's `RemainAfterExit=`.
    See [Task and Run](task-and-run.md) for more details
  * `oncrash = "reboot"` -- when all retries have failed, and the
    service has *crashed*, the system is rebooted
  * `oncrash = "script"` -- similarly, but instead of rebooting, call
    the `exec-stop-post` script with exit code `crashed`, see below

Service directories
-------------------

Five settings ask Finit to create a directory for the service before it
starts, owned by its `user` and `group`, mode 0755.  The value is a
directory name, resolved under a fixed base -- absolute paths and `..`
are refused:

| Setting | Base | Environment variable |
|---|---|---|
| `runtime-dir` | `/run` | `RUNTIME_DIRECTORY` |
| `state-dir` | `/var/lib` | `STATE_DIRECTORY` |
| `cache-dir` | `/var/cache` | `CACHE_DIRECTORY` |
| `logs-dir` | `/var/log` | `LOGS_DIRECTORY` |
| `config-dir` | `/etc` | `CONFIGURATION_DIRECTORY` |

Each resolved path is exported to the process environment under the
listed name, the same names systemd uses for `RuntimeDirectory=` and
friends.  As in systemd, `config-dir` is the odd one out: it is created
but never chowned.

Each takes a matching `-mode`, e.g. `runtime-dir-mode = 0700`, default
0755.  Modes are octal, with the leading zero.

The mode of the named directory is locked down again on every start.
Its contents are left alone as long as the owner is right; if the owner
has drifted, everything under it is chowned back.

The runtime directory is removed again when the service stops, after
any `exec-stop-post` script has run; `/run` is a tmpfs so it would not
survive a reboot anyway.  The other four persist.  A completed `run` or
`task` counts as stopped, unless `remain-after-exit` keeps it alive
until stopped for real.  `runtime-dir-preserve` adjusts this, same
values as systemd's `RuntimeDirectoryPreserve=`:

  * `"no"` -- removed when the service stops, the default
  * `"restart"` -- kept across restarts, removed on a real stop
  * `"yes"` -- never removed

This is what lets a service drop privileges and still create, and
later touch, its own PID file:

    service ntpd {
        user        = "ntp"
        group       = "ntp"
        runtime-dir = "ntpd"
        pidfile     = "/run/ntpd/ntpd.pid"
        command     = "/usr/sbin/ntpd -n -p /run/ntpd/ntpd.pid"
    }

These settings exist only in the block format.

Stopping and reloading
----------------------

When stopping a service, either manually or when moving to another
runlevel, Finit starts by sending `SIGTERM` to let the process shut
down gracefully.  If it has not been collected within 3 seconds,
`SIGKILL` follows.  Both ends of that are configurable:

  * `stop-signal = "SIGPWR"` -- send this instead of `SIGTERM`
  * `stop-timeout = 10` -- seconds to wait before `SIGKILL`, 1-300

Some services need more than a signal:

  * `exec-stop = "script [args]"` -- run instead of sending the stop
    signal, and instead of `stop` for `sysv`
  * `exec-reload = "script [args]"` -- run instead of sending `SIGHUP`.
    Like systemd, Finit sets `$MAINPID` as a convenience to scripts,
    which in effect also allows `exec-reload = "kill -HUP $MAINPID"`

If a daemon cannot be reloaded with a signal at all, say so and Finit
restarts it instead:

    service dropbear {
        reload-signal = "none"
        command       = "/usr/sbin/dropbear -R -F"
    }

`SIGHUP` is the default and the only other accepted value, with or
without the `SIG` prefix and in any case.

Scripts
-------

Services, including the `sysv` variant, support six lifecycle scripts:

  * `exec-start-pre` -- called before the sysv/service is started
  * `exec-start-ready` -- called when the sysv/service is ready
  * `exec-stop` -- called instead of the stop signal
  * `exec-stop-post` -- called after the sysv/service has stopped
  * `exec-reload` -- called instead of `SIGHUP`
  * `exec-cleanup` -- called when run/task/sysv/service is removed

Each takes a matching `-timeout`, in seconds, 0-3600, after which Finit
kills the script.  It defaults to the `stop-timeout` value and can be
disabled by setting it to zero:

    service foo {
        exec-start-pre         = "/etc/foo/pre.sh"
        exec-start-pre-timeout = 10
        command                = "/usr/sbin/foo"
    }

These scripts run as the same user and group as the service itself,
with any `envfile` sourced.  They are executed from the `$HOME` of the
given user.  The scripts are not called with any argument, but get a
set of environment variables:

  * `SERVICE_IDENT=foo:1`
  * `SERVICE_NAME=foo`
  * `SERVICE_ID=1`

The `exec-stop-post` script is called with an additional set of
environment variables.  Yes, the text is correct, the naming was an
accident:

 - `EXIT_CODE=[exited,signal,crashed]`: normal exit, signaled, or
   crashed
 - `EXIT_STATUS=[num,SIGNAME]`: set to one of exit status code from
   the program, if it exited normally, or the signal name (`HUP`,
   `TERM`, etc.) if it exited due to signal

When a run/task/sysv/service is removed (disable + reload) it is first
stopped and then removed from the runlevel.  The `exec-stop-post`
script always runs when the process has stopped, and `exec-cleanup`
runs when the block has been removed from the runlevel.

> [!IMPORTANT]
> These script actions are intended for setup, cleanup, and readiness
> notification.  A script that outlives its timeout is killed, so pick
> one that suits the work, or set it to zero to opt out and take
> responsibility for the script terminating.