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I'm more tempted to say that systemd does well what previously you needed a dozen half-broken tools to implement. For example, isolating the /tmp of an applica

by mgbmtl 11y ago

I'm more tempted to say that systemd does well what previously you needed a dozen half-broken tools to implement. For example, isolating the /tmp of an application, monitoring the process and restarting if necessary, more logging options (and imho cleaner/more efficient). Then again, all this has been debated over and over again. In practice, people are adopting it. Haters are noisy. It's like reading about debates on IPv6 migration strategies.

vezzy-fnord 11y ago
Process supervisors with reliable logging are nearly two decades old at this point. Isolating /tmp is then a namespacing feature, which in a system where execution state is composed as an explicit external manifest via chain loading (as opposed to serializing from a unit file into a private ExecContext structure, as with systemd) should be completely orthogonal to any one service manager. Else it is inflexible if it needs complex internal scaffolding. (Actually I think supervision goes back to IBM's SRC in at least 1992, but I'm not exactly sure if the earliest versions had anything beyond process management.)
- XorNot 11y ago
  Process supervision goes back a long away...and has pretty much never been included out of the box in any server-oriented Linux distros. It also looks a lot more like systemd in systems with good process supervision like Solaris.
  - vezzy-fnord 11y ago
    Which is a failure of people making server distros, not those writing process supervisors. Not at all. SMF supports delegated restarters, its milestones can contain far more state information (and explicitly) than targets can, it uses a configuration repository which enables runtime dynamic service state modification at a far higher rate than the relatively static systemd, its dependency system is simpler, it's integrated with the hardware fault manager (also to provide service resource identifiers beyond the COMM name), its profiles are more granular than presets, it has explicit service instance support and logging is flat file-based in /var/svc/log. SMF has plenty of its own issues, but it's quite different from systemd. I think the delegation aspect is one of its most valuable lessons, but ultimately I also believe it's too overarching for a modern init.
- digi_owl 11y ago
  I think one thing that gave systemd adoption a big boost was a declaration from the maintainer of the cgroups sub-system of Linux. At present multiple processes can set up and manage cgroups, but the maintainer wants to change to there being a single user space manager. Thus systemd was pushed as "the" cgroups user space process. You can already seeing the systemd devs behaving as if this was a done deal. Ran into a email a while back about systemd clobbering a libvirt managed cgroup. And in it Poettering "suggested" that libvirt should hand control over to systemd as it would be THE cgroups manager going forward. You can probably find similar encounters between, say, Docker and systemd.

by mgbmtl 11y ago

vezzy-fnord 11y ago

Process supervisors with reliable logging are nearly two decades old at this point. Isolating /tmp is then a namespacing feature, which in a system where execution state is composed as an explicit external manifest via chain loading (as opposed to serializing from a unit file into a private ExecContext structure, as with systemd) should be completely orthogonal to any one service manager. Else it is inflexible if it needs complex internal scaffolding. (Actually I think supervision goes back to IBM's SRC in at least 1992, but I'm not exactly sure if the earliest versions had anything beyond process management.)

XorNot 11y ago
Process supervision goes back a long away...and has pretty much never been included out of the box in any server-oriented Linux distros. It also looks a lot more like systemd in systems with good process supervision like Solaris.
- vezzy-fnord 11y ago
  Which is a failure of people making server distros, not those writing process supervisors. Not at all. SMF supports delegated restarters, its milestones can contain far more state information (and explicitly) than targets can, it uses a configuration repository which enables runtime dynamic service state modification at a far higher rate than the relatively static systemd, its dependency system is simpler, it's integrated with the hardware fault manager (also to provide service resource identifiers beyond the COMM name), its profiles are more granular than presets, it has explicit service instance support and logging is flat file-based in /var/svc/log. SMF has plenty of its own issues, but it's quite different from systemd. I think the delegation aspect is one of its most valuable lessons, but ultimately I also believe it's too overarching for a modern init.
digi_owl 11y ago
I think one thing that gave systemd adoption a big boost was a declaration from the maintainer of the cgroups sub-system of Linux. At present multiple processes can set up and manage cgroups, but the maintainer wants to change to there being a single user space manager. Thus systemd was pushed as "the" cgroups user space process. You can already seeing the systemd devs behaving as if this was a done deal. Ran into a email a while back about systemd clobbering a libvirt managed cgroup. And in it Poettering "suggested" that libvirt should hand control over to systemd as it would be THE cgroups manager going forward. You can probably find similar encounters between, say, Docker and systemd.