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Bedrock Linux
Bedrock Linux 1.0beta2 Nyla
TODO: adjtime
The rc.conf configuration file, located at /bedrock/etc/rc.conf, is used to
populate a number of important environment variables.
TZ variable indicates timezone information. It can be in one of three forms:
/bedrock/etc/localtime and direct TZ to that. For
example, copy /usr/share/zoneinfo/America/New_York if you are in EST/EDT.Some software may ignore the TZ environment variable and instead attempt to
read /etc/localtime to determine the current timezone. Bedrock Linux will
copy /bedrock/etc/localtime to /etc/localtime when enabling a stratum
to cover this possibility.
Sets the language/locale information.
e.g.: LANG=en_US.UTF-8
Note locale information must be installed/generated in every statum, as it
is currently set to local to avoid conflicts.
Sets the normal user POSIX PATH variable. These are the directories in which
programs look for executables. If you aren't sure what to put here, you almost
certainly want the value in the example below. Note that /etc/profile (which
should be sourced by your shell when it starts) will add items to the beginning
and end of this variable to make it play with Bedrock specific functionality.
e.g.: NPATH=/opt/bin:/usr/local/bin:/usr/bin:/bin
Sets additional directories for the super user's (aka root's) POSIX PATH variable. Same general idea as above, but for the root user who probably needs access to the s* directories that the non-root user does not.
e.g.: SPATH=/opt/sbin:/usr/local/sbin:/usr/sbin:/sbin
This is a list of directories used by the man executable to find man pages.
If you alter this from the default, be sure to also change
/bedrock/etc/brp.conf as well.
e.g. MANPATH="/usr/local/share/man:/usr/share/man"
This is a list of directories used by the info executable to find info
documentation. If you alter this from the default, be sure to also change
/bedrock/etc/brp.conf as well.
e.g. INFOPATH="/usr/local/share/info:/usr/share/info"
This is a list of directories that contain directories used by the
freedesktop.org standard. For example, the items here could contain "icon"
directories which contain icons to be used by GUI programs. For another
example, it could contain an "applications" directory which contains .desktop
files that are used to populate application menus and mime/default programs.
If you alter this from the default, be sure to also change
/bedroock/etc/brp.conf as well.
e.g. XDG_DATA_DIRS="/usr/local/share:/usr/share"
Per-stratum configuration is read from /bedrock/etc/strata.conf and
whatever files are found in /bedrock/etc/strata.d/. Typically most
strata will use the same, default configuration. However, occasionally it
is necessary or useful to adjust it, either for all stratum or just a
handful of individual stratum.
share indicates a given path should be considered global, i.e. that
everything should see the same set of files at any of these paths rather than
their own version. New mount points in any of these directories will also be
treated as global (mount --share'd). e.g.:
share = /proc, /sys, /dev, /home, /root, /lib/modules, /tmp, /var/tmp, /mnt share = /media, /run
bind is similar to share except new mount points made under these
directories are not treated as global. This is primarily used to avoid
recursion where one global item is mounted within another. In general,
anything set to be global in /bedrock should be bind'd rather than
share'd. e.g.
bind = /bedrock, /bedrock/brpath, /bedrock/strata/bedrock
Careful with the order - directories should come before what they contain.
One cannot rename() the share or bind items. This is problematic for some
files in /etc which (1) have neighboring items which are local (and so we
cannot share all of /etc) and (2) which are updated via rename(). Any files
which hit the above two situations should be union'd. One can break up share
and bind items if the lines get to long, but union items have a picky syntax;
keep all of the items that are contained in the same directory on the same
line. e.g.:
union = /etc: profile, hostname, hosts, passwd, group, shadow, sudoers, resolv.conf, machine-id, shells, systemd/system/multi-user.target.wants/bedrock.service, locale.conf, motd, issue, os-release, lsb-release, rc.local
Bedrock Linux has hooks to run executables before/after enabling/disabling a
stratum. If you would like to do something such as ensure a
stratum-specific mount point is mounted before enabling a stratum,
these hooks could be utilized to achieve this. For example, you could check if
an NFS mount point is mounted on /bedrock/strata/ and,
if it is not, mount it just before enabling the networked-stratumstratum. You could then
unmount it when disabling the stratum.
e.g.:
preenable = /bedrock/share/brs/force-symlinks preenable = /bedrock/share/brs/setup-etc preenable = /bedrock/share/brs/run-lock
enable indicates if the given stratum should be enabled at boot time. This
can either be boot (indicating it should be enabled at boot time) or
manual (indicating it will be enabled/disabled manually). e.g.
enable = boot
If multiple enable items are set, the latest one takes precidence. Thus, one
can include enable = boot in a framework (frameworks described below)
and then override it with a stratum-specific enable = manual.
Generally one would want enable = boot; however, if some stratum is
rarely used it may be best left to manual.
init indicates the given stratum can provide an init system. The value
should be the command to run at boot if this stratum is chosen to provide init.
The value is the entire line after the =; do not place multiple init commands
in the same line separated by ,'s as one can do with share. Historically,
/sbin/init is utilized as the command to run the init; however, systemd
systems seem to prefer /lib/systemd/system without a corresponding symlink at
/sbin/init. e.g.:
init = /sbin/init
Note multiple init values can be provided if a given stratum provides
multiple init systems; all of the resulting values will be listed in the
init-selection menu.
When enabling a stratum, Bedrock Linux will mount some filesystems (e.g.
from other stratum.conf settings such as share), and then proceed to unmount
filesystems when disabling the stratum. To manage this sanely, Bedrock Linux
expects the stratum to have no mount points when disabled.
If there is some exception where Bedrock Linux should accept a pre-existing
mount point when enabling a stratum, or leave some mount point mounted when
disabling a stratum, this can be indicated via the unmanaged setting. For
example, of a stratum's root directory is mounted over NFS, one could indicate
Bedrock Linux should not touch a mount point at root via:
unmanaged = /
Nonetheless it is useful to manage such mount points, e.g. ensure the NFS mount
is mounted at stratum enable. To do this use the preenable and
postdisable hooks.
"framework" is used to inherit settings placed in
/bedrock/etc/frameworks.d/. This is useful to avoid
excessive repetition when multiple strata share the same settings. e.g.framework-name
framework = default
Most strata should use framework = default, with the notable exception of
the global stratum which should use framework = global.
Aliases can be created for strata. In most contexts the alias can be used
in place of the stratum, e.g. with brc and bri. Bedrock Linux requires
some aliases for tracking singleton strata, but you are free to create
others to your liking.
Alias information is read from /bedrock/etc/aliases.conf and from the files
found in /bedrock/etc/aliases.d/. Simply indicate the desired alias name
followed by an = and then the stratum it is aliased to. For example,
Debian releases are often referred to by their current state in the development
process in addition to their name. Thus:
oldstable = wheezy stable = jessie testing = stretch unstable = sid
When stretch becomes stable, the aliases can be adjusted accordingly so "stable" points to the new stable release.
The file at /bedrock/etc/brp.conf is responsible for managing the filesystem
at /bedrock/brpath filesystem which is the underlying mechanism for the
implicit access rules. The brpath filesystem is used to make files from
other strata accessible, altering them as necessary so things "just work".
If any strata provides a file, this file could be made accessilbe through
the /bedrock/brpath filesystem for the other strata.
The [pass], [brc-wrap] and [exec-filter] headings should contain
key-value pairs separated by an equals sign. The keys will indicate
files/directories that should show up at /bedrock/brpath, and the values will
indicate files/directories that will be unioned to populate the mount point's
files.
For the keys, a trailing "/" indicates the item should be a directory (and thus the values will be used to populate files in the directory). Otherwise, the item is treated as a file and the values indicate possible files it could represent.
For the values, a prefixed stratum (e.g. "stratum:/path/to/file")
indicates the value corresponds to that specific stratum's file/directory.
Otherwise, all of the enabled strata will be searched as possible sources
for the file.
The [stratum-order] heading should be followed by a list of strata, one
per line. These indicate the priority order for values that do not have a
stratum:strata not listed will still be used; they will simply be treated as
lower priority than the those listed.
An example brp.conf:
# Nothing special with this "pass" category, it just passes files through # untouched. [pass] /man/ = /usr/local/share/man, /usr/share/man /info/ = /usr/local/share/info, /usr/share/info /icons/ = /usr/local/share/icons, /usr/share/icons /firmware/ = /lib/firmware /zoneinfo/ = /usr/share/zoneinfo # This will wrap all items it finds in a script that calls brc to set the local # context. This is important for executables to "just work". [brc-wrap] /bin/ = /usr/local/bin, /usr/bin, /bin /sbin/ = /usr/local/sbin, /usr/sbin, /sbin # By convention, items in "/pin/" are given a higher priority than even local # files. This is used, for example, to ensure a given executable which is # strongly related to the init system is always tied to the init system. /pin/bin/systemctl = init:/usr/bin/systemctl, init:/bin/systemctl /pin/bin/rc-service = init:/usr/bin/rc-service, init:/bin/rc-service /pin/bin/rc-status = init:/usr/bin/rc-status, init:/bin/rc-status /pin/bin/rc-update = init:/usr/bin/rc-update, init:/bin/rc-update /pin/sbin/poweroff = init:/usr/sbin/poweroff, init:/sbin/poweroff, init:/usr/bin/poweroff, init:/bin/poweroff /pin/sbin/reboot = init:/usr/sbin/reboot, init:/sbin/reboot, init:/usr/bin/reboot, init:/bin/reboot /pin/sbin/shutdown = init:/usr/sbin/shutdown, init:/sbin/shutdown, init:/usr/bin/shutdown, init:/bin/shutdown /pin/sbin/halt = init:/usr/sbin/halt, init:/sbin/halt, init:/usr/bin/halt, init:/bin/halt /pin/sbin/systemctl = init:/usr/sbin/systemctl, init:/sbin/systemctl /pin/sbin/rc-service = init:/usr/sbin/rc-service, init:/sbin/rc-service /pin/sbin/rc-status = init:/usr/sbin/rc-status, init:/sbin/rc-status /pin/sbin/rc-update = init:/usr/sbin/rc-update, init:/sbin/rc-update # This will modify some of the fields in the freedesktop standard .desktop # items to fix local context issues. [exec-filter] /applications = /usr/local/share/applications, /usr/share/applications [stratum-order] # Add strata here in the order you want them to take priority when multiple # ones provide a file. One stratum per line. centos debian arch
strata.conf/strata.d/ indicates which init system(s) a given stratum
can provide, if any. The user is then (optionally) prompted during boot to
chose which of them to use for the given session. /bedrock/etc/brn.conf can
be used to configure a default stratum/command pair for init as well as a
timeout for the init selection menu.
timeout indicates the amount of time, in seconds, the user is provided to
make a selection before the default is automatically chosen. Set to 0 to
indicate no time should be provided - always boot directly into the configured
default. Set to -1 to indicate no time limit - nothing will be chosen
automatically, the user has as much time as desired.
To chose a default stratum, set the default_stratum = and default_cmd
items accordingly. With those set, a user can simply hit enter at the menu and
the default item will be chosen. Moreover, if a timeout is set, the default
item will be chosen when the timeout expires.
The content below revolves around three configuration files:
/etc/fstab/bedrock/etc/fstab/bedrock/etc/frameworks.d/defaultThe first - /etc/fstab - is global by default. If you are editing it at
install time - when you're not yet actually running Bedrock Linux - the file
may be at $GLOBAL/etc/fstab (e.g. /bedrock/strata/global/etc/fstab), and
not directly at /etc/fstab quite yet. The latter two should be at
/bedrock/etc/fstab irrelevant of the circumstances: either you're hijacking
such that it is on the root, or you're doing a manual install and have made a
symlink for /bedrock.
Bedrock Linux provides a menu on boot to let the user choose which init system
to use for the given session. Naturally this menu must be provided before the
init system is run, which means it must be provided before /etc/fstab is
parsed by the init system. If the init system is on a partition other than the
boot-time root partition, this partition must be mounted by something other
than /etc/fstab. For these mounts Bedrock Linux provides its own pre-init
time fstab file at /bedrock/etc/fstab.
Some users prefer to make a partition specifically for /bedrock/strata or one
for each strata within /bedrock/strata (e.g. a partition for
/bedrock/strata/gentoo, a partition for /bedrock/strata/slackware, etc).
Since these partitions can potentially contain init systems,
/bedrock/etc/fstab was created specifically to support these workflows. If
you do not have special partitions for/within /bedrock/strata, but rather
kept that directory on the root partition, you probably do not need to worry
about /bedrock/etc/fstab. However, you may still need to worry about the
default framework - keep reading below.
Other common mount points - such as /home and /tmp - can use /etc/fstab
just as they are utilized in other distros. Nonetheless, if you would like to
have /bedrock/etc/fstab mount partitions such as /home it can do so.
Be sure not to include the same mount item in both /etc/fstab and
/bedrock/etc/fstab - any given mount should only appear in one or the other.
When you place anything in /bedrock/etc/fstab make sure you do not also have
it within /etc/fstab.
For the most part, /bedrock/etc/fstab utilizes the same syntax as the typical
/etc/fstab. However, there are a few special things to keep in mind for
/bedrock/etc/fstab:
/bedrock/etc/fstab is mounted by the Bedrock Linux provided busybox
executable in a limited environment. It may not understand some less common
fstab features which would have been understood in /etc/fstab. For those
features, /etc/fstab will be required. It is possible to run into a
catch-22 in which some special fstab command that busybox does not
understand is required to provide a given init - avoid these situations.
Since /bedrock/etc/fstab is mounted so early - before init - various
Bedrock Linux subsystems are not yet enabled. For example, the systems in
place to ensure global files are available in the same place from
everyone's point-of-view or that rootfs stratum's files are available at
the explicit path /bedrock/strata/ are not yet
enabled. Thus, special consideration must be utilized when mounting into
either the rootfs-stratum-name/global or rootfs strata.
The rootfs stratum is on the root of the filesystem tree, i.e. /, from
/bedrock/etc/fstab's point of view. Thus, if you would like to place
rootfs' /boot on its own partition, it should be mounted at /boot and
not, for example, /bedrock/strata/jessie/boot.
/bedrock is considered part of the rootfs stratum, and thus anything in
/bedrock should be mounted directly onto the root of the filesystem tree.
For example, if you have /bedrock/strata on its own partition, it should
mount the partition onto /bedrock/strata.
Any global mount points, such as /home or /tmp, should be mounted in the
global stratum. If global is also rootfs, then /home should be
mounted to /home. However, if global is not rootfs, /home should
be mounted to /bedrock/strata/. The default
framework settings will then ensure it is accessible in the other strata.global-stratum-name/home
Order matters. Any mount point which contains a directory in which another device will be mounted should be mounted first.
Additionally, the default framework should be made aware of some of these
additional mount points; place such changes into
/bedrock/etc/frameworks.d/default. Any mount points in /bedrock/ should be
configured as bind items. For example, if you made /bedrock/strata its own
partition, add
bind = /bedrock/strata
and the /bedrock/strata mounted in in /bedrock/etc/fstab will be made
accessible in the other strata. Careful not to double up - ensure there is
only one bind item for any given bind directory. For example, by default
Bedrock Linux is configured with a bind item for /bedrock/run - no need to
make another one for that directory.
Any mount global mount points should be configured as share items. For
example, if you made /var/log its own partition and wish for it to be
considered global, add
share = /var/log
to the default framework. Again, careful not to double up - ensure there is
only one instance of any given share item. For example, /home should be
configured as a share item by default and should not be added again.