Bedrock Linux 0.7 Poki Advanced Workflows

• Manually Adding Strata
• Removing the Hjiacked Stratum
• Pinning executables to strata

Manually Adding Strata

brl fetch can be used to automate acquiring Linux distributions for use as strata. However, this supports a limited number of distros and requires an internet connection. Strata may also be created manually, which may be preferred in some situations.

To manually add a stratum, get its contents into a new directory within /bedrock/strata corresponding to the new stratum's name. For example:

• mkdir -p /mnt/example
• mount /dev/sda1 /mnt/example
• cp -a /mnt/example /bedrock/strata/example

Or for another example:

• mkdir -p /bedrock/strata/example
• cd /bedrock/strata/example
• wget http://example.com/root.tar
• tar xf root.tar
• rm root.tar

Ensure the new stratum name does not contain any whitespace characters, forward or back slashes, colons, equal signs, dollar signs, or single or double quotes. Moreover, ensure it does not start with a dash character. At the time of writing, Bedrock's implementation naively assumes these constraints to be in place.

By default, new strata are hidden to avoid accidentally being enabled while the files are mid transfer into place. Once you have completed placing the new stratum's files into /bedrock/strata, show the stratum:

• brl show new-stratum

Finally, to actually use the stratum, enable it:

• brl enable new-stratum

New, manually acquired strata may complain about missing users or groups. If so, you may need to manually add them. Such strata may also complain about locale issues, in which case you may need to manually set up the given stratum's locale.

Removing the Hjiacked Stratum

The stratum resulting from the hijack of the initial install may be removed. Some considerations:

• The stratum currently providing init may not be removed (as that would crash the system). If you are using the hijacked stratum, first reboot and select another stratum to provide init for the session.
• By default, the hijacked stratum maintains your bootloader. After removing the hijacked stratum the bootloader will continue to work - you can boot - but it will not automatically update with new kernels or initrds. If you know how to manually maintain the bootloader, you are welcome to do so. If you would prefer to have another stratum maintain the bootloader, simply install its bootloader over the existing one. Many distros provide a grub or grub2 package which is suitable. It may be wise to do this first, before removing the hijacked stratum, to ensure the bootloader hand-off goes smoothly before removing the hijacked stratum.
• Bedrock creates a hijacked alias during the hijack process which can be used to determine which stratum is the hijacked one, should you have forgotten: brl deref hijacked
• brl remove command can be used to remove strata, such as the hijacked stratum:

brl remove $(brl deref hijacked)

Pinning executables to strata

If multiple strata provide the same command, absent any additional indication of which to use Bedrock will choose one by default in a given context. Which it chooses may be configured, which is referred to as "pinning."

/bedrock/etc/bedrock.conf's [cross-bin] section is used to configure executable binaries in /bedrock/cross. In this section,

pin/bin/command = stratum:/local/path/to/command

entries are used to specify the specified stratum:path pair should provide the given command, should the pair exist. For example,

pin/bin/vim = arch:/usr/bin/vim

indicates that the arch stratum should provide vim by default if it has it (and if strat is not used to manually specify which stratum should provide the command).

Multiple stratum:path pairs may be specified, in which case the first which provides the path will provide the command. For example,

pin/bin/firefox = clear:/usr/bin/firefox, arch:/usr/bin/firefox

stratum: may be left off with only a path provided, in which case all enabled strata are considered. However, this is not useful for pinning.

If you typically restrict the command, be sure to configure it under the restriction section as well.