Installing Ruby with ruby-install

30 Jan 2019 17:40 direnv ruby

On recent versions of Ubuntu, with older versions of Ruby, you’ll get an error about missing openssl. See this post for a solution.

Install ruby-install:

https://github.com/postmodern/ruby-install/archive/refs/tags/v0.8.3.tar.gz

mkdir -p ~/.direnv/
cd ~/.direnv/
wget -O ruby-install-0.8.5.tar.gz \
    https://github.com/postmodern/ruby-install/archive/v0.8.5.tar.gz

tar -xzvf ruby-install-0.8.5.tar.gz
ln -sf ruby-install-0.8.5 ruby-install

Create ~/.direnv/bin/ruby-install:

mkdir -p ~/.direnv/bin/
cat > ~/.direnv/bin/ruby-install <<'EOF'
#!/bin/sh
~/.direnv/ruby-install/bin/ruby-install \
    --no-install-deps --src-dir ~/.rubies/src --cleanup $@
EOF

chmod +x ~/.direnv/bin/ruby-install

The --no-install-deps above prevents ruby-install from attempting to, well, install dependencies. If you leave this off, it’ll run a sudo apt install (or whatever) on your behalf, which leaves you with an annoying password prompt.

The list of dependencies is in the dependencies.txt file, so we can install them ourselves:

# Debian, Ubuntu, etc.
sudo apt install $(
grep '^apt:' \
    ~/.direnv/ruby-install/share/ruby-install/ruby/dependencies.txt | \
    cut -d: -f2- )

On a Mac with Homebrew, it’s slightly different:

# macOS with Homebrew
grep '^brew:' \
    ~/.direnv/ruby-install/share/ruby-install/ruby/dependencies.txt | \
    cut -d: -f2- | xargs brew install

# per the Homebrew caveats from above
export LDFLAGS="-L/opt/homebrew/opt/openssl@1.1/lib"
export CPPFLAGS="-I/opt/homebrew/opt/openssl@1.1/include"
export LDFLAGS="-L/opt/homebrew/opt/libffi/lib"
export CPPFLAGS="-I/opt/homebrew/opt/libffi/include"

Then install your chosen Ruby version (e.g. 2.7.4):

~/.direnv/bin/ruby-install ruby 2.7.4

Apple Silicon

If you’re on a recent Mac with Apple Silicon (arm64), you need to add --enable-shared, per https://www.rubyonmac.dev/how-to-install-ruby-on-macos-12-6-apple-silicon:

~/.direnv/bin/ruby-install ruby 2.7.4 -- --enable-shared

Installation location

The above commands will install Ruby 2.7.4 to ~/.rubies/ruby-2.7.4, which is where direnv will look for it.

Listing available Ruby versions

$ ~/.direnv/bin/ruby-install
Stable ruby versions:
  ruby:
    2.6.10
    2.7.6
    3.0.4
    3.1.2
  jruby:
    9.3.9.0
... etc.

Updating available Ruby versions

$ ~/.direnv/bin/ruby-install -L
>>> Downloading latest ruby versions ...
>>> Downloading latest jruby versions ...
...etc.

Edited 2021-12-04: Update to ruby-install 0.8.3; more current Ruby versions.
Edited 2022-11-07: Update to ruby-install 0.8.5; add macOS arm64; more current Ruby versions.