# Ruby on Archlinux

I thought I would document my setup, since it's somewhat non-standard but working quite well for me.

## What this does

* Install major Ruby versions at their latest patch release
* Allow to switch between them seamlessly
* Use chruby
* Encourage bundler usage

## What this does not

* Install files outside your home folder that are not tracked by your package manager
* Use ruby-install, ruby-build, rbenv or RVM
* Allow you to switch to a specific outdated patchlevel version of Ruby, out of the box.

## Setup

`yay` is used as an example AUR helper, use whichever you like or do it manually. Prefixed with `#` means run as root, prefixed with `$` means run as the user you regularly work with.

```bash
# pacman -S ruby
$ yay -S chruby ruby-bundler
$ mkdir -p ~/.rubies/3.0/bin
$ ln -s /usr/bin/ruby ~/.rubies/3.0/bin/ruby
$ echo "gem: --no-user-install --env-shebang" > ~/.gemrc
```

Unfortunately the `ruby2.7` package in `community` changed the packaging style compared to what has been done historically. To make it available we need another symlink:

```bash
$ mkdir -p ~/.rubies/2.7/bin
$ ln -s /usr/bin/ruby-2.7 ~/.rubies/2.7/bin/ruby
``` 

Edit your `~/.$SHELLrc` and add:

```bash
# chruby
source /usr/share/chruby/chruby.sh
source /usr/share/chruby/auto.sh
RUBIES=(/opt/ruby* $HOME/.rubies/*)
```

Optionally, but the entire point of this setup, install older Ruby versions:

```bash
$ yay -S ruby2.6 ruby2.6-bundler ruby2.7
```

If you want to make other Ruby distributions available just add them to `RUBIES` if they provide a `bin/ruby`. Else symlink them into `.rubies` like we did above for `ruby2.7`.

## Upgrading

When the [ruby package](https://www.archlinux.org/packages/extra/x86_64/ruby/) moves to a new minor or major version (`major.minor.teensy`), do the following (adjusting the versions of course):

```bash
$ mv ~/.rubies/3.0 ~/.rubies/3.1
```

Most likely I or somebody else will upload a package for the old release to the AUR:

```bash
$ yay -S ruby3.0
```

Depending on how it's packaged you might need to add a new symlink to `.rubies`.

## Per project setup

Create a `.ruby-version` file with the desired version to use, like

```
2.7
```

Use a `Gemfile` and `bundle install` to install gems into your home folder, or `bundle install --path vendor/bundle` to install gems to a per project directory.


## System wide gem installation

Do not do `gem install` as root, install the packages from the AUR like we already did for `ruby-bundler`, `ruby2.7-bundler` and so on. If the gem you want to install system wide isn't packaged yet, create one! Have a look at existing packages for inspiration or facilitate tools like [gem2arch](https://aur.archlinux.org/packages/gem2arch/).

## Scripting

Use `/usr/bin/chruby-exec 2.7 -- regular command` to switch to a different Ruby environment in your scripts. This only works for scripts run as users that have this setup. Same holds true for systemd units, while you can use `chruby-exec` in `ExecStart` and friends, your service needs to have a `User=` to one with this setup.