3cb2f5f369
If a file is specified in loader_conf_files that ends in '.lua', lualoader will now load and execute that file. These may be used in place of a traditional loader.conf to use more complicated logic, where some values may be set based on others or based on the environment that the C bits has left us with. Lua scripts are run in a limited environment. In particular, it does not get access to any modules or, in-fact, anything except environment variable. A config.buildenv hook has been added so that a local module can add whatever it may need to to the environment. When a global var is set in the lua script, it does not immediately alter the loader environment. Instead, the script's environment is initially empty and processed only if the whole script executes successfully. Effectively, a lua configuration file either takes effect or it does not, an error will not leave it in a half-baked state. Reviewed by: bcr (manpages), imp Differential Revision: https://reviews.freebsd.org/D28450
78 lines
2.7 KiB
Groff
78 lines
2.7 KiB
Groff
.\"
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.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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.\"
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.\" Copyright (c) 2020 Kyle Evans <kevans@FreeBSD.org>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd May 10, 2023
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.Dt LOADER.CONF.LUA 5
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.Os
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.Sh NAME
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.Nm loader.conf.lua
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.Nd Lua-based system bootstrap configuration file
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.Sh DESCRIPTION
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When the lua-based
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.Xr loader 8
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encounters a filename in
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.Va loader_conf_files
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that has a
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.Dq .lua
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suffix, it will be loaded and executed by the lua interpreter in a limited
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environment.
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.Pp
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The limited environment does not contain the ability to reference or load other
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lua modules.
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Existing loader environment variables may be referenced as if they were already
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defined global variables.
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.Pp
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A lua configuration file may set any global variable, which will subsequently
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be processed and added to the environment after execution of the configuration
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file has completed.
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Other than the
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.Ar exec
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setting, all variables described in
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.Xr loader.conf 5
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operate the same in the
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.Nm
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environment.
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Note that the settings describing module options can only be set in the
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environment; there is currently no way for a
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.Pa loader.conf.lua
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to fetch them.
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At this time, global table and function values are ignored.
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.Pp
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The
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.Fn config.buildenv
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hook will be run with an empty environment provided to it that may be populated
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by a custom
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.Pa local.lua .
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.Sh SEE ALSO
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.Xr loader.conf 5
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.Sh AUTHORS
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The mechanism for loading
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.Nm
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files was originally written by
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.An Kyle Evans Aq Mt kevans@FreeBSD.org .
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