systemd Status Update (original) (raw)

It has been a while since my original announcement of systemd. Here's a little status update, on what happened since then. For simplicity's sake I'll just list here what we worked on in a bulleted list, with no particular order and without trying to cover this comprehensively:

• systemd has been accepted as Feature for Fedora 14, and as it looks right now everything worked out nicely and we'll ship F14 with systemd as init system.
• We added a number of additional unit types: .timer for cron-style timer-based activation of services, .swap exposes swap files and partitions the same way we handle mount points, and.path can be used to activate units dependending on the existance/creation of files or fill status of spool directories.
• We hooked systemd up to SELinux: systemd is now capabale of properly labelling directories, sockets and FIFOs it creates according to the SELinux policy for the services we maintain.
• We hooked systemd up to the Linux auditing subsystem: as first init system at all systemd now generates auditing records for all services it starts/stops, including their failure status.
• We hooked systemd up to TCP wrappers, for all socket connections it accepts.
• We hooked systemd up to PAM, so that optionally, when systemd runs a service as a different user it initializes the usual PAM session setup and teardown hooks.
• We hooked systemd up to D-Bus, so that D-Bus passes activation requests to systemd and systemd becomes the central point for all kinds of activation, thus greatly extending the control of the execution environment of bus activated services, and making them accessible through the same utilities as SysV services. Also, this enables us to do race-free parallelized start-up for D-Bus services and their clients, thus speeding up things even further.
• systemd is now able to handle various Debian and OpenSUSE-specific extensions to the classic SysV init script formats natively, on top of the Fedora extensions we already parse.
• The D-Bus coverage of the systemd interface is now complete, allowing both introspection of runtime data and of parsed configuration data. It's fun now to introspect systemd with gdbusor d-feet.
• We added a systemd PAM module, which assigns the processes of each user session to its own cgroup in the systemd cgroup tree. This also enables reliable killing of all processes associated with a session when the user logs out. This also manages a secure per-user /var/run-style directory which is supposed to be used for sockets and similar files that shall be cleaned up when the user logs out.
• There's a new tool systemd-cgls, which plots a pretty process tree based on the systemd cgroup hierarchy. It's really pretty. Try it!
• We now have our own cgroup hierarchy beneath/cgroup/systemd (though is will move to /sys/fs/before the F14 release).
• We have pretty code that automatically spawns a getty on a serial port when the kernel console is redirected to a serial TTY.
• systemctl got beefed up substantially (it can even draw dependency graphs now, via dot!), and the SysV compatiblity tools were extended to more completely and correctly support what was historically provided by SysV. For example, we'll now warn the user when systemd service files have changed but systemd was not asked to reload its configuration. Also, you can now use systemd's native client tools to reboot or shut-down an Upstart or sysvinit system, to facilitate upgrades.
• We provide a reference implementation for the socket activation and other APIs for nicer interaction with systemd.
• We have a pretty complete set of documentationnow, some of it even extending to areas not directly related to systemd itself.
• Quite a number of upstream packages now ship with systemd service files out-of-the-box now, that work across all distributions that have adopted systemd. It is our intention to unify the boot and service management between distributions with systemd, and this shows fruits already. Furthermore a number of upstream packages now ship our patches for socket-based activation.
• Even more options that control the process execution environment or the sockets we create are now supported.
• Earlier today I began my series of blog stories on systemd for administrators.
• We reimplemented almost all boot-up and shutdown scripts of the standard Fedora install in much smaller, simpler and faster C utilities, or in systemd itself. Most of this will not be enabled in F14 however, even though it is shipped with systemd upstream. With this enabled the entire Linux system gains a completely new feeling as the number of shells we spawn approaches zero, and the PID of the first user terminal is way < 500 now, and the early boot-up is fully parallelized. We looked at the boot scripts of Fedora, OpenSUSE and Debian and distilled from this a list of functionality that makes up the early boot process and reimplemented this in C, if possible following the bahaviour of one of the existing implementations from these three distributions. This turned out to be much less effort than anticipated, and we are actually quite excited about this. Look forward to the fruits of this work in F15, when we might be able to present you a shell-less boot at least for standard desktop/laptop systems.
• We spent some time reinvestigating the current syslog logic, and came up with an elegant and simple scheme to provide /dev/logcompatible logging right from the time systemd is first initialized right until the time the kernel halts the machine. Through the wonders of socket based activation we first connect the /dev/logsocket with a minimal bridge to the kernel log buffer (kmsg) and then, as soon as the real syslog is started up as part of the later bootup phase, we dynamically replace this minimal bridge by the real syslog daemon -- without losing a single log message. Since one of the first things the real syslog daemon does is flushing the kernel log buffer into log files, all logged messages will sooner or later be stored on disk, regardless whether they have been generated during early boot, late boot or system runtime. On top of that if the syslog daemon terminates or is shut down during runtime, the bridge becomes active again and log output is written to kmsg again. The same applies when the system goes down. This provides a simple an robust way how we can ensure that no logs will ever be lost again, and logging is available from the beginning of boot-up to the end of shut-down. Plymouth will most likely adopt a similar scheme for initrd logging, thus ensuring that everything ever logged on the system will properly end up in the log files, whether it comes from the kernel, from the initrd, from early-boot, from runtime or shutdown. And if syslogd is not around, dmesg will provide you with access to the log messages. While this bridge is part of systemd upstream, we'll most likely enable this bridge in Fedora only starting with F15. Also note that embedded systems that have no interest in shipping a full syslogd solution can simply use this syslog bridge during the entire runtime, and thus making the kernel log buffer the centralized log storage, with all the advantages this offers: zero disk IO at runtime, access to serial and netconsole logging, and remote debug access to the kernel log buffer.
• We now install autofs units for many "API" kernel virtual file systems by default, such as binfmt_misc orhugetlbfs. That means that the file system access is readily available, client code no longer has to manually load the respective kernel modules, as they are autoloaded on first access of the file system. This has many advantages: it is not only faster to set up during boot, but also simpler for applications, as they can just assume the functionality is available. On top of that permission problems for the initialization go away, since manual module loading requires root privileges.
• Many smaller fixes and enhancements, all across the board, which if mentioned here would make this blog story another blog novel. Suffice to say, we did a lot of polishing to ready systemd for F14.

All in all, systemd is progressing nicely, and the features we have been working on in the last months are without exception features not existing in any other of the init systems available on Linux and our feature set already was far ahead of what the older init implementations provide. And we have quite a bit planned for the future. So, stay tuned!

Also note that I'll speak about systemd at LinuxKongress 2010 in Nuremberg, Germany. Later this year I'll also be speaking at the Linux Plumbers Conference in Boston, MA. Make sure to drop by if you want to learn about systemd or discuss exiciting new ideas or features with us.