| foo | If I have something in /etc/init - I forget, is that systemd ? | 16:21 |
|---|---|---|
| jelly | foo: /etc/init is for upstart, but if files merely exists that's not proof they're used and upstart is actually running | 16:26 |
| foo | jelly: how can I be sure? This is a system that has been online for 5+ years. I believe upstart is older and systemd is newer? | 16:30 |
| jelly | foo: which ubuntu release is this | 16:32 |
| jelly | lsb_release -a | 16:33 |
| JanC | if it has been online for 5+ years, it's probably out of support... | 16:34 |
| foo | jelly: Ubuntu 14.04.5 LTS | 16:35 |
| foo | JanC: not yet, I've been keeping an eye on that | 16:35 |
| jelly | foo: that one used upstart. | 16:35 |
| foo | I mean, it's getting there, but... :) | 16:35 |
| JanC | well, not 5+ years then | 16:35 |
| foo | jelly: thank you | 16:35 |
| foo | JanC: I've still been upgrading over those 5 years. :) | 16:35 |
| jelly | dpkg -S /sbin/init | 16:35 |
| JanC | or you upgraded it | 16:35 |
| foo | JanC: give a foo some credit! ;) | 16:36 |
| foo | jelly: aha, thank you: upstart: /sbin/init | 16:36 |
| foo | so, if I was to do a fresh install of ubuntu lts today, that would not use upstart - right? | 16:36 |
| jelly | 16.04 was the first LTS that switched over to systemd | 16:36 |
| foo | got it. I believe systemd can support deps, can upstart do that as well? eg. I have a handful of processes I either want to associate with 1 parent, or I want to have one of the children depend on the other children | 16:37 |
| JanC | upstart uses events to start/stop services based on what other services started/stopped | 16:39 |
| JanC | in addition to the manpages, http://upstart.ubuntu.com/cookbook/ is probably the best source for upstart knowledge | 16:39 |
| foo | JanC: perfect, I'll take a look there - thanks. I wrote some python code to manually do "service ___ start/stop" ... but recently was advised to do this all in my git-hook and take it out of python. Makes sense. Actually, if I do it in a git-hook, I guess I don't need to make the services depend on a parent to make it easy, I'll simply add a new service there | 16:40 |
| foo | in the git-hook | 16:41 |
| * foo scratches head | 16:41 | |
| JanC | "service" has the advantage of working with (almost) every init system, but you probably want to restart only one service, and have all dependent service restarted automatically too | 16:45 |
| foo | JanC: yup, that would certainty be helpful at this point in time. I assume that's in the cookbook, checking now | 16:50 |
| foo | 6.33.2 Start depends on another service | 16:53 |
| foo | start on started other-service | 16:53 |
| foo | Does that mean: A) the service won't start if the other one isn't running or B) the service will start and it'll automatically start the other-service ? | 16:53 |
| JanC | it means the service will be started after the other-service has started | 16:57 |
| JanC | so more or less A) | 16:57 |
| foo | Aha, ok | 16:59 |
| foo | I don't think there is a way, with upstart at least, to say "if this service starts, start this other service too if it's not running" - correct? | 16:59 |
| foo | Can't seem to find that, anyway | 17:00 |
| JanC | you'd define that in the configuration of other-service | 17:00 |
| JanC | or you can start it in pre-start script | 17:01 |
| foo | JanC: how would I define it in the other-service is what I don't seem to be able to find | 17:01 |
| foo | ah, pre-start | 17:01 |
| foo | JanC: specifically, I'm looking at python long-running processes | 17:02 |
| JanC | in the configuration of other-service, you put "start on starting service" (where "service" is the first service) | 17:02 |
| foo | ahh, so the child is told when to start, not a parent conf that says to start children | 17:03 |
| foo | JanC: thank you! that distinction makes sense, I think I'm following now | 17:03 |
| foo | JanC: now, I wonder if it makes sense to have A) dummy parent, that doesn't really do much, but several children start when parent starts or B) just pick a child and make other children start when it starts. Is there a best practice/preference here? | 17:04 |
| foo | We basically have 1 piece of software that has 4 long running python processes associated with it (eg. services) | 17:04 |
| JanC | you might want to look at the other services on the system to see how they depend on each other | 17:04 |
| JanC | if the 4 processes have no clear dependency on each other it might work to have some sort of meta-service indeed | 17:07 |
| foo | JanC: yeah, they don't have a clear dependency, which is why I'm leaning towards that... but I'm wondering, is there shorthand for making a meta-service? | 17:07 |
| foo | eg. I can create a bash script that does nothing but sleep every second... but I'm wondering if there is something less hack-ish | 17:07 |
| JanC | just don't have an exec statement in it | 17:22 |
| foo | oh, heh, easy enough | 17:26 |
| foo | I thought there was something, thank you Jan! | 17:26 |
| JanC | you would have "start on starting meta-service" and "stop on stopping meta-service" in each of the "subservices", or something like that | 17:31 |
| foo | JanC: yup, that would do the trick. When I upgrade to the latest ubuntu early next year, I suspect I'll have to change this for systemd | 17:35 |
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