Automatically fetch latest ruby-build version with 24h cache

.gitignore

@@ -1 +1,2 @@
 ruby-build
+ruby-build-source

README.md

@@ -27,15 +27,17 @@ RUBY_APPLY_PATCHES=$'dir/1.patch\n2.patch\nhttp://example.com/3.patch' asdf inst
 RUBY_APPLY_PATCHES=$(curl -s https://raw.githubusercontent.com/rvm/rvm/master/patchsets/ruby/2.1.1/railsexpress) asdf install ruby 2.1.1
 ```
 
-> [!NOTE]
-> This plugin does not automatically fetch new Ruby versions. Running `asdf plugin update ruby` will update asdf-ruby and ensure the latest versions of Ruby are available to install. If the desired ruby version is still not showing up see the below [Troubleshooting](https://github.com/asdf-vm/asdf-ruby?tab=readme-ov-file#troubleshooting) section.
+By default asdf-ruby automatically fetches the latest release of ruby-build, so new Ruby versions are available as soon as ruby-build supports them.
 
-By default asdf-ruby uses a recent release of ruby-build, however instead you can choose your own branch/tag through the `ASDF_RUBY_BUILD_VERSION` variable:
+You can pin to a specific ruby-build version/branch/tag with the `ASDF_RUBY_BUILD_VERSION` environment variable:
 
 ```
-ASDF_RUBY_BUILD_VERSION=master asdf install ruby 2.6.4
+ASDF_RUBY_BUILD_VERSION=v20240101 asdf install ruby 3.3.0
+ASDF_RUBY_BUILD_VERSION=master asdf install ruby 3.3.0
 ```
 
+Set `ASDF_RUBY_SKIP_RUBY_BUILD_UPDATE=1` to skip the network check and reuse whatever ruby-build refs are already cached locally.
+
 ## Default gems
 
 asdf-ruby can automatically install a set of default gems right after
@@ -68,7 +70,7 @@ note that you might have to change `.ruby-version` to include full version (e.g.
 ## Troubleshooting
 
 > [!NOTE]
-> The most common issue reported for this plugin is a missing Ruby version. If you are not seeing a recent Ruby version in the list of available Ruby versions it's likely due to having an older version of this plugin. Run `asdf plugin update ruby` to get the most recent list of Ruby versions. If it is still not showing up then this plugin's `RUBY_BUILD_VERSION` in lib/utils.sh likely needs updated with the latest ruby-build release https://github.com/rbenv/ruby-build/releases. Please check for an existing PR before submitting a new one. If there is not one, please fork the repo and submit one. If this plugin's ruby-build needs updated, you can workaround it with `ASDF_RUBY_BUILD_VERSION`. A note in the above [Use](https://github.com/asdf-vm/asdf-ruby?tab=readme-ov-file#use) section describes how to do this.  
+> If you are not seeing a recent Ruby version, check ruby-build's releases at https://github.com/rbenv/ruby-build/releases to see if it's been added yet.  
 
 If you are moving to asdf-ruby from another Ruby version manager, it is recommended to completely uninstall the old Ruby version manager before installing asdf-ruby.
 

lib/utils.sh

@@ -1,7 +1,6 @@
 #!/usr/bin/env bash
 
-RUBY_BUILD_VERSION="${ASDF_RUBY_BUILD_VERSION:-v20260503}"
-RUBY_BUILD_TAG="$RUBY_BUILD_VERSION"
+RUBY_BUILD_REPOSITORY="https://github.com/rbenv/ruby-build.git"
 
 echoerr() {
   echo >&2 -e "\033[0;31m$1\033[0m"
@@ -17,54 +16,98 @@ ensure_ruby_build_setup() {
 }
 
 ensure_ruby_build_installed() {
-  local current_ruby_build_version
-
-  if [ ! -f "$(ruby_build_path)" ]; then
-    download_ruby_build
-  else
-    current_ruby_build_version="$("$(ruby_build_path)" --version | cut -d ' ' -f2)"
-    # If ruby-build version does not start with 'v',
-    # add 'v' to beginning of version
-    # shellcheck disable=SC2086
-    if [ ${current_ruby_build_version:0:1} != "v" ]; then
-      current_ruby_build_version="v$current_ruby_build_version"
-    fi
-    if [ "$current_ruby_build_version" != "$RUBY_BUILD_VERSION" ]; then
-      # If the ruby-build directory already exists and the version does not
-      # match, remove it and download the correct version
-      rm -rf "$(ruby_build_dir)"
-      download_ruby_build
+  local source_dir target_ref
+  source_dir="$(ruby_build_source_dir)"
+
+  if ! ensure_ruby_build_source "$source_dir"; then
+    if [ -f "$(ruby_build_path)" ]; then
+      echoerr "Warning: Could not access ruby-build source; using existing installation."
+      return 0
     fi
+    errorexit "Failed to clone ruby-build. Check your network connection."
+  fi
+
+  target_ref="$(resolve_ruby_build_ref "$source_dir")" ||
+    errorexit "Could not determine ruby-build version."
+
+  if needs_install "$target_ref"; then
+    install_ruby_build "$source_dir" "$target_ref"
+  fi
+}
+
+# Maintain a persistent clone of ruby-build. Cheap `git fetch` on each install
+# keeps tag list current; set ASDF_RUBY_SKIP_RUBY_BUILD_UPDATE=1 to bypass.
+ensure_ruby_build_source() {
+  local source_dir="$1"
+
+  if [ ! -d "$source_dir/.git" ]; then
+    echoerr "Cloning ruby-build..."
+    rm -rf "$source_dir"
+    git clone "$RUBY_BUILD_REPOSITORY" "$source_dir" >/dev/null 2>&1 || return 1
+    return 0
+  fi
+
+  if [ -n "${ASDF_RUBY_SKIP_RUBY_BUILD_UPDATE:-}" ]; then
+    return 0
   fi
+
+  git -C "$source_dir" fetch --tags --prune origin >/dev/null 2>&1 ||
+    echoerr "Warning: Could not update ruby-build, using cached refs."
+  return 0
 }
 
-download_ruby_build() {
-  # Print to stderr so asdf doesn't assume this string is a list of versions
-  echoerr "Downloading ruby-build..."
-  # shellcheck disable=SC2155
-  local build_dir="$(ruby_build_source_dir)"
+# Pick the ref to check out: explicit env var > latest release tag.
+resolve_ruby_build_ref() {
+  local source_dir="$1"
 
-  # Remove directory in case it still exists from last download
-  rm -rf "$build_dir"
+  if [ -n "${ASDF_RUBY_BUILD_VERSION:-}" ]; then
+    echo "$ASDF_RUBY_BUILD_VERSION"
+    return 0
+  fi
 
-  # Clone down and checkout the correct ruby-build version
-  git clone https://github.com/rbenv/ruby-build.git "$build_dir" >/dev/null 2>&1
-  (
-    cd "$build_dir" || exit
-    git checkout "$RUBY_BUILD_TAG" >/dev/null 2>&1
-  )
+  local latest
+  latest="$(git -C "$source_dir" tag --list 'v*' --sort=-v:refname | head -1)"
+  if [ -n "$latest" ]; then
+    echo "$latest"
+    return 0
+  fi
+  return 1
+}
 
-  # Install in the ruby-build dir
-  PREFIX="$(ruby_build_dir)" "$build_dir/install.sh"
+needs_install() {
+  local target_ref="$1" installed_version
+  [ ! -f "$(ruby_build_path)" ] && return 0
 
-  # Remove ruby-build source dir
-  rm -rf "$build_dir"
+  installed_version="$("$(ruby_build_path)" --version | cut -d ' ' -f2)"
+  if [ "${installed_version:0:1}" != "v" ]; then
+    installed_version="v$installed_version"
+  fi
+  [ "$installed_version" != "$target_ref" ]
+}
+
+install_ruby_build() {
+  local source_dir="$1" ref="$2"
+  echoerr "Installing ruby-build ${ref}..."
+
+  local checkout_ref="$ref"
+  if git -C "$source_dir" show-ref --verify --quiet "refs/remotes/origin/$ref"; then
+    checkout_ref="origin/$ref"
+  fi
+  git -C "$source_dir" checkout --detach "$checkout_ref" >/dev/null 2>&1 ||
+    errorexit "Failed to checkout ruby-build ref ${ref}."
+
+  rm -rf "$(ruby_build_dir)"
+  local install_dir
+  install_dir="$(cd "$(asdf_ruby_plugin_path)" && pwd)/ruby-build"
+  PREFIX="$install_dir" "$source_dir/install.sh" ||
+    errorexit "Failed to install ruby-build."
 }
 
 asdf_ruby_plugin_path() {
   # shellcheck disable=SC2005
   echo "$(dirname "$(dirname "$0")")"
 }
+
 ruby_build_dir() {
   echo "$(asdf_ruby_plugin_path)/ruby-build"
 }