Pre/Post hooks

[HeapUnderfl0w]

User Story

I am administrating several arkservers for a small community using LGSM, and i have found
myself in need of a Pre and/or Post hook system (Mainly Post-update, Pre-start).

This is due to a (not directly related) bug in SteamCMD that makes mods of >1GiB size fail to download on the first attempt, and i wanted to write a tool that basically handles that downloading instead of SteamCMD directly. But as i am using LGSM, i would have to either wrap the whole lgsm script (which would be possible, but not really elegant) or completely reinvent it for Ark.

Basic info

• Distro: Debian GNU/Linux 9.12 (stretch)
• Game: Ark Survival Evolved
• Command: update / start
• LinuxGSM version: v19.12.5

Further Information

Arguments

The hooks themselves dont need to provide a lot of information really, mainly 3 arguments.

1. Game
2. Instance Name
3. Install Path

The motivation for using args (or, if needed environment variables) is that it does not rely on any bash-internals, and thus hooks can be written in any language that can be called as a file.
(bash, python, nodejs, it would even enable the use of things like sciptisto or directly compiling the hook to a binary.

Installation

I would envision either a simple directory like hooks under the default lgsm config path
or a more complicated hooks/[pre|post]-[target] directory where multiple scripts get executed in alphabetical order order (with target being the name of the command, like start, stop, ...).

Running

Given the 3 arguments specified above lgsm should only have to call the script / program like this
(with LGSM_DIR being the lgsm install directory)

$LGSM_DIR/hooks/post-update arkserver yourfancyinstance /home/arkuser/serverfiles/

Additionally, if 1 hook exits with a non 0 exit code, lgsm should abort completly.

Further Reading

Here i was mainly inspired by both pacman Pre/Post Transaction hooks and git hooks