minit - a small yet feature-complete init

If you want to take part in minit, please subscribe to the minit mailing list (send an empty email to minit-subscribe@fefe.de).

Download

Download minit-0.10.tar.bz2 (gnupg sig) now!

Or use the anonymous CVS archive at :pserver:cvs@cvs.fefe.de:/cvs (empty password) and check out minit.

Since so many people asked for it, here is the /etc/minit directory from by laptop as tarball.

Fridtjof Busse also wrote some documentation about minit which may help you with the setup.

Download the slides to a talk about minit I gave at Linux Kongress 2004: minit-linux-kongress2004.pdf

What works so far

• It can start services and take dependencies into account.
• It can restart services
• It can start services in sync mode (i.e. wait until they terminate, to get around race conditions for static initializations)
• There is a companion utility "msvc" that can be used much in the same way as the svc from daemontools. Communication works over two fifos, /etc/minit/in and /etc/minit/out. Those have to exist before minit is started and they should be owned by root and have mode 600.
• There is a companion utility "pidfilehack" that can be used to do stuff like run ssh, wait a while, read the PID off /var/run/sshd.pid and tell minit this PID so it will know when sshd exits and can restart it.
• It can pipe stdout to a dedicated log process.

Wishlist

(in no particular order)

• is able to boot off a completely read-only system (i.e. does not modify file system) [CHECK!]
• contains a robust logging system [CHECK!]
• configuration like /var/qmail, not like inittab (i.e. each option in a separate file, no parsing) [CHECK!]
• minimal memory and disk footprint [CHECK!]
• dependencies, i.e. a service can specify that it depends on a number of other services and init will start those automatically. [CHECK!]
• static initializations are handled by a separate process (to keep init memory footprint low). [turned out to be not much code]
• an easy way to extract the PID of a given service from minit, so shell scripts can send signals to daemons. [CHECK!]
• an easy way to tell init not to restart a given process [CHECK!]
• an easy way to tell init to start an additional service [CHECK!]

By "easy way" I mean that the process is readily automatable, i.e. a single command line, not that it is especially easy to understand for Unix newbies.

See also

• utmp helper for minit, by Nikola Vladov.
• the need(8) dependency concept by Richard Gooch
• runit, a "minimal replacement for sysvinit" by Gerrit Pape.
• initng, a new Gentoo boot system by Jimmy Wennlund (he says it was inspired by minit)
• jinit is a init written in C++ implementing the need(8) concept
• sysmaster - the static initialization part of init with a configuration scheme similar to the one I have in mind
• upstart 0.0.1. Unfortunately, no documentation whatsoever.
• sysvinit - the standard Linux init, for reference
• proton hacked a truly minimal custom init in x86-linux assembler. Just 2 pages of memory; one page code, one page stack. He even got rid of the one page of read-only data that is normally there.
• Nico wrote both a minit howto and his own init replacement, cinit
• busybox - embedded linux super-utility. Contains a lot of utilities and a small init.