Add options to set ulimit configures

[robsonpeixoto]

Some process need to open to many files, like prometheus, and you need to configure the number of files a process can open.
But the poise-service to have this feature.

Some useful links:

• upstart: http://bazaar.launchpad.net/~upstart-devel/upstart/trunk/view/head:/init/man/init.5#L906
• systemd: https://www.freedesktop.org/software/systemd/man/systemd.exec.html#LimitCPU=

The sysvinit and inittab just need to execute the ulimit command on the script.

But what's the better way to implement it? As a provider option or as a poise_service option?

Thanks

[coderanger]

Is there a reason to not do this in the command for the service?

You could use something like command "bash -c 'ulimit -whatever && myapp'" or something like chpst from Runit. If you really want to do it in service framework, I would make a custom service template and point at that.

[robsonpeixoto]

@coderanger It'll work, but IMO is not a elegant solution.

And is better add a exec before execute myapp. It'll avoid a lot of errors with signal command "bash -c 'ulimit -whatever && exec myapp'"

[coderanger]

Yeah, something like that :) Not against supporting it as a provider option per se but I'm trying to avoid tooooo much template sprawl.

[robsonpeixoto]

If you would like, I can implement it as a provider option and open a PR.

[coderanger]

That would be a long term project to figure out how best to integrate so I would just use one of the workarounds from above for now.

[robsonpeixoto]

I'm already using the bash -c ... workarround.

[alicebob]

But ulimit && mything won't play nice with a non-root user= argument. (I need to set the number of open files). Even having a free-form key-value hash which ends up in the config would already be nice.

(I need to set LimitNOFILE somewhere)

[coderanger]

@alicebob Indeed, you can use a custom template file for all the core providers to fully override things not otherwise exposed in the API.