Bedrock Linux 1.0alpha4 Flopsie Plans

This page serves to describe plans for the then-upcoming release of Bedrock Linux, 1.0alpha4 "Flopsie". Flopsie has since been released on 2013/12/30. The following is thus out-of-date, but is kept in case anyone is curious.

/etc issue fix

All public releases of Bedrock Linux prior to Flopsie have been unable to properly share several files in /etc such as /etc/passwd. Manual work-arounds have been available but are unsatisfactory in the long term. Flopsie will include a new FUSE union filesystem (tentatively named "brf") which should be able to properly handle the /etc issue situation. In theory this new filesystem could completely replace bind-mounts for Bedrock Linux and significantly simplify the mount table; however, brf will likely have a non-negligable performance overhead and is thus only current intended to patch corner-cases in which bind-mounts are insufficient.

Installation scripts

Most of Bedrock Linux's development time has gone towards how it works under-the-hood. Aspects of installation have been extremely low priority. Flopsie will being the efforts to turn this around. It will include a POSIX shell script which will automate some of Flopsie's installation steps. To aid this, several things which were previously up to the end-user will now be standardized. This includes the standard C library for core components (planned to be musl) and the installation location for clients (planned to be /bedrock/clients/)

brs updates

brs will be updated to include the following capabilities:

• Set up mount points for a client on a live, running system. Combine with brg below this should make it relatively easy to spin up a new client.
• Remove all mount points for a client on a live, running system.
  • This will make it easy to either temporarily disable a given client or remove it completely.
• Detect the state of a given client.
  • Has all required mounts, has some required mounts, has no required mounts
  • Is providing some processes, is not providing any processes

bri updates

bri will be updated to include the follow changes:

• bri will be able to indicate which client is providing a given process
  • It can tell from a given PID or program name (it will use busybox's pidof internally)
• bri will be able to list all of the process provided by a given client.
• Some changes will be made to -w and/or -W
  • People have been finding the difference between the two confusing; one will likely be dropped.

brw updates

As of Bosco, brw is just a short alias to bri -n; that is, brw will indicate which client provides calling program (usually a shell). Flopsie will have brw be an alias for bri -w (or -W) if at least one argument is provided so that brw program-name will indicate which client will provide a given executable, since this, like bri -n, is very commonly used.

brg (delayed to hawky)

Flopsie will include a new Bedrock Linux utility, brg, which can be used to acquire a new client. For example (syntax still tentative):

brg debian 6.0 amd64 wheezy

Could be used to install a x86_64 Debian 6.0 client in /bedrock/clients/wheezy. This will hopefully be able to get the client from one of the following sources:

• an openvz template (very portable, should almost always be available)
• debootstrap or febootstrap 2.X (if the command is available - install in a client to use)
• archbootstrap if dependencies are met (currently depends on bash which is not provided by busybox).
• gentoo stage3 tarballs

Note that it will only provide a client available from sources which are available. If you'd like to install a Linux distribution which is not provided from one of the above sources, you will have to fall back to installing it manually (such as via its normal installation method on another partition or in a VM and then copying the contents out).

brp update (delayed to hawky)

The current release of Bedrock Linux, 1.0alpha3 "Bosco", requires users run the brp utility every time an executable is added or remove from the system.

Bosco also lacks the ability to cleanly ensure that a given executable is always provided by a given client, or that a given executable is always provided only locally.

Flopsie plans to address both of these issues with a new brp. This brp will be a FUSE filesystem that will effectively populate the brpath directories on-the-fly and thus always be up-to-date. It will be configurable to ensure a listed executables are always provided by a given client or never provided through the brpath system at all.

Additionally, Bosco does not have a clean way to ensure a given executable is always provided by the same client, irrelevant of what the client may have natively. These two issues will be addressed with a FUSE virtual filesystem . It will be mounted at /bedrock/brpath/ and have something along the following root-level directory structure:

• /bedrock/brpath/prebin/
• /bedrock/brpath/presbin/
• /bedrock/brpath/postbin/
• /bedrock/brpath/postsbin/
• /bedrock/brpath/reparse_configs

To improve performance, the contents of the configuration files this new brp will utilize will be cached rather than re-read as needed. Thus manual work is necessary to inform a mounted brp filesystem that their contents have changed. Something like this is expected:

echo 1 > /bedrock/brpath/reparse_configs

brinfo virtual filesystem (cancelled)

There were prior plans to include a virtual filesystem which can be accessed to get information about Bedrock-related systems akin to procfs or sysfs. However, this is no longer planned for Flopsie. It may or may not be picked up again in another release.