Earlier this month, I started experimenting with LOVE2D and how I’d develop a game. There’s a lot to take in and I’m really still learning the basics in the spare time that I have.

One of the things that I’m not a big fan of is that Lua doesn’t have a standard package manager - there’s Luarocks, but very few LOVE-related packages actually have a rockspec. I’m still working out how to include Luarocks packages properly within LOVE. I found loverocks and will look into it very soon.

Given that I use git, it follows that I could just use git submodules, but my experience with them has been frustrating - and not everything I want to use is actually in git. I want to bundle certain things that aren’t source code. git submodules don’t help in this regard.

What I really needed was a “generic dependency manager”. I searched for a while, and found something that seemed like exactly what I wanted: peru.

Enter… peru

peru is a dependency manager that can handle git, svn, hg, raw downloads - pretty much anything you need. It can be further extended by custom plugins, but I haven’t yet had to implement one.

Peru allows pinning to certain revisions or tags, effectively helping push to reproducible builds. It can also update dependencies automatically for you with the reup command.

One thing that made me extremely happy is how configurable peru.yaml is.

For example, I have some .so and .dll files I want to move into a specific directory. With peru, I can do this easily:

imports:
  # specific to amd64 nix
  lib_64_so: ./

curl module lib_64_so:
  url: https://server.org/release/lib-amd64.tar.gz
  unpack: tar

lib-amd64.tar.gz includes a README, as well as a LICENSE file. I don’t need the README - but I do need the license. I also don’t want to clobber my own README with this download - or any other dependency. Peru allows this to solve me - easily.

curl module lib_64_so:
  url: https://server.org/release/lib-amd64.tar.gz
  unpack: tar
  drop:
    - README
  move:
    lib64.so: dest/lib64.so
    LICENSE: vendor/libso_64.LICENSE

Now I can easily track the license file - in case the project ever goes out - and move the .so directly where I need it.

For curl-based dependencies, you can also specify a hash via the sha1 field:

curl ...:
  sha1: the-hash-i-trust

Helps me reconcile downloading dependencies that may change - I know the last version I knew worked (or trusted).

git, too!

Peru is really easy to use with git-based dependencies, too, with none of the git submodule business (directly). Just like curl modules, I can drop some of the files I don’t actually want.

imports:
  lualib: ./

git module lualib:
  url: https://server.org/lualib
  drop:
    - README.md
    - main.lua
  move:
    lib.lua: src/thirdparty/lib.lua
    LICENSE: vendor/lib_lua.LICENSE
  rev: git-hash

Recursive!

If one of your targets actually has a peru.yaml file, you can recursively download that target’s dependencies, too!

git module lualib_recursive:
  url: https://server.org/lualib_recursive
  recursive: true

If you only need a specific dependency of a dependency, you can skip recursive and reference it in your own imports section, eg:

imports:
  dependency.sub_dependency: ./target

... definition of dependency ...

jj ZZ

Since I started learning some game dev things, I’ve been treating it like any standard software project: tests, build scripts, CI, dependency management, asset management…

It has definitely been a distraction, and I know that real game development companies have their own tooling for stuff like this - but I’m glad I was able to find something simple that does exactly what I need without being overly complicated.