Using an init system for many instances of simple programs

OpenRC for quark and ii etc.

Using OpenRC runlevels to have lots of instances of simple (network) programs like quark for multiple http serving locally or ii (or sic) for IRC server connections.

To keep programs simple, they should not do the same process for unrelated uses. It is much more complicated to configure and manage multiple webservers in the same process (like how nginx does it) than just one. Init systems are designed to manage processes, and should be used instead. Do one thing etc. etc.

This is how to use the OpenRC runlevels for quark and ii runlevels as examples.

The Tree (on my machine)

/etc/runlevels
├── boot
│   └── ...
├── default
│   └── ...
├── irc-base
│   ├── oftc -> /etc/init.d/oftc
│   ├── liberachat -> /etc/init.d/liberachat
│   └── ...
├── net-base
│   ├── default -> ../default
│   └── quark -> ../quark
├── net-offline
│   ├── default -> ../default
│   └── net-base -> ../net-base
├── net-dns
│   ├── dnscrypt-proxy -> /etc/init.d/dnscrypt-proxy
│   └── unbound -> /etc/init.d/unbound
├── net-wifi
│   ├── dhcpcd -> /etc/init.d/dhcpcd
│   ├── net-base -> /etc/runlevels/net-base
│   ├── net-dns -> /etc/runlevels/net-dns
│   └── wpa_supplicant -> /etc/init.d/wpa_supplicant
├── net-wifi-irc
│   ├── irc-base -> ../irc-base
│   └── net-wifi -> ../net-wifi
├── quark
│   ├── quark-docs -> /etc/init.d/quark-docs
│   ├── quark-equwal -> /etc/init.d/quark-equwal
│   └── ...
├── shutdown
│   └── ...
└── sysinit
    └── ...

as you can see, IRC is connected after the real internet on wifi (net-wifi), but quark runs on any network runlevel using net-base.

How To:

OpenRC has its own commands for making the runlevels, but I find them confusing. Let's just edit the files.

# make runlevel
mkdir /etc/runlevels/quark
# add services (as many as needed)
ln -s /etc/int.d/quark-whatever /etc/runlevels/quark
# add runlevel to parent
ln -s /etc/runlevels/default /etc/runlevels/quark
# Reload since openrc is in default
openrc default

That works, but what about for networked IRC on a custom networking runlevel? Just add it to the networking runlevel.

# (first, make a network runlevel that contains default! Without default the system will crash, obviously.)
mkdir /etc/runlevels/net-wifi
ln -s /etc/runlevels/net-wifi /etc/runlevels/default
ln -s /etc/init.d/wpa_supplicant /etc/runlevels/net-wifi
# etc.
# Now add the irc-base to the network runlevel
mkdir /etc/runlevels/irc-base
ln -s /etc/init.d/liberachat irc-base
ln -s /etc/init.d/oftc irc-base
ln -s /etc/runlevels/irc-base /etc/runlevels/net-wifi
openrc net-wifi

Tool: restart-runlevel

Openrc wants switch the whole stack openrc runlevel so I made a little tool to just restart a specific runlevel. Nice for debugging.

#!/bin/bash

for link in /etc/runlevels/${1}/*
do [[ -L "$link" && "$(readlink "$link")" == /etc/init.d/* ]] && \
    rc-service "$(basename "$link")" restart
done

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