s6 VS tini

A (rare) good critique to systemd can be found here. Written by the developer behind s6, which happens to be scheduled to replace OpenRC on Alpine Linux. For completeness-sake, some of the main reasons why Alpine doesn't prefer systemd do not apply on most other distros.

It got mass-adopted while being imperfect, so that's to be expected. Thankfully its inception and the criticism that followed have paved the way for the likes of dinit and s6.

this page and this page, both by Laurent Bercot, creator of s6.

Of the two I have experience with, runit is simpler and thus easier to get the hang of than s6-rc/s6. Though the s6 (not s6-rc) docs at the author's site contain a lot of info (including apologetics and rationales) that applies almost equally well to runit

systemd: Yes; it's awaiting its "PipeWire". Thankfully, the likes of s6 and dinit are very promising. Though I can actually appreciate that systemd is addressed. As ultimately it helps in raising awareness that will benefit whatever software will replace it eventually.

Arguably this is less troublesome to solve compared to the other concerns. As we're inevitably waiting for the system supervision suite that will be to systemd what PipeWire has been to PulseAudio. I'm very optimistic about this as both s6 and Dinit are shaping up lovely.

Using the s6-service add command I added a service called "libvertd" when I ment to put "libvirtd". Now when I run s6-db-reload it spits out a error message saying "undefined service name libvertd". But I cant remove it using s6-service remove libvertd because that just spits out a generic help message and doesn't change anything. I also couldn't find documentation on https://skarnet.org/software/s6/ or https://skarnet.org/software/s6-rc/ as the command just *doesn't* exist on those pages. (also no man or info page).

yes busybox httpd or civetweb is even smaller, both around 300kb.

for tini you mean https://github.com/krallin/tini? how large is your final docker image, why not just alpine in that case which is musl+busybox

Tini, a useful process manager for containerized apps

Ah gotcha. I believe it can be baked into images as well, per the entrypoint example in the readme: https://github.com/krallin/tini

Not sure how this will fare IRL in k8s as I haven’t much experience there. It’s still silly that this is the default behavior where you need something like Tini, but I digress.

To be fair, even for running a single process the pitfalls are real. I've been seeing Tini[1] a lot for these situations.

I just read in the README that Tini is included by Docker since 1.13 if using --init flag.

[1] https://github.com/krallin/tini

The default init process used is the first docker-init executable found in the system path of the Docker daemon process. This docker-init binary, included in the default installation, is backed by tini.

AFAIK It's for the init process to reparent zombie processes. See TINI

The second easiest (and most common when your entry point is a bash script) is to use a fake init tool like tini