Remove experimental CNB support (#1464)

The buildpack in this repo is primarily a classic Heroku buildpack,
however, as part of the initial exploration into CNBs had experimental
CNB support added some time ago.

However, the maintained Ruby CNB now exists in a separate repo:
https://github.com/heroku/buildpacks-ruby

The experimental CNB support in this repo doesn't actually work any more
since the buildpack API version it implements (v0.2) isn't supported by
modern `lifecycle` versions - and attempts at building encounter this
error:

```
ERROR: failed to set API for Buildpack 'heroku/ruby@0.1.4': buildpack API version '0.2' is incompatible with the lifecycle
```

In addition, it's not even possible to use this repo with a CNB build
without having cloned it locally, since:
1. The CNB parts are no longer published
2. The old CNB release assets were deleted a year or so ago:
   https://github.com/heroku/heroku-buildpack-ruby/releases
3. Pack/lifecycle doesn't support cloning Git URLs.
4. Attempting to use a buildpack URL pointing at the GitHub gzip archive
   fails due to GitHub's nesting of the repo inside a subdirectory:

```
$ pack build --builder heroku/builder:22 --buildpack https://github.com/heroku/heroku-buildpack-ruby/archive/refs/heads/main.tar.gz ruby-test
...
Downloading from https://github.com/heroku/heroku-buildpack-ruby/archive/refs/heads/main.tar.gz
93.2 KB/-1 B
ERROR: failed to build: downloading buildpack: extracting from https://github.com/heroku/heroku-buildpack-ruby/archive/refs/heads/main.tar.gz: reading buildpack: reading buildpack.toml: could not find entry path 'buildpack.toml': not exist
```

Given both the Buildpack API error, and the GitHub URL issues no one is
using the CNB implementation here, and so its dead code that should be
removed to prevent confusion (eg over where the CNB lives).

A deprecation warning was previously added in #1445 (though as above
it's unlikely anyone even saw that message, since the build was already
erroring before it gets that far).

.github/workflows/ci.yml

@@ -19,4 +19,4 @@ jobs:
       - name: Run ShellCheck bin top level
         run: |
             shellcheck bin/support/bash_functions.sh bin/support/download_ruby -x &&
-            shellcheck bin/build bin/compile bin/detect bin/release bin/test bin/test-compile -x
+            shellcheck bin/compile bin/detect bin/release bin/test bin/test-compile -x

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## [Unreleased]
 
+- Remove experimental CNB support. For official CNB support use [heroku/buildpacks-ruby](https://github.com/heroku/buildpacks-ruby) instead. (https://github.com/heroku/heroku-buildpack-ruby/pull/1464)
 
 ## [v271] - 2024-06-03
 

bin/detect

@@ -1,18 +1,10 @@
 #!/bin/sh
 
-if [ -z "$CNB_STACK_ID" ]; then
-  # v2 API
-  APP_DIR=$1
-else
-  _PLATFORM_DIR=$1
-  _PLAN=$2
-  # v3 API
-  APP_DIR=$(pwd)
-fi
+APP_DIR=$1
 
 if [ -f "$APP_DIR/Gemfile" ]; then
   echo "Ruby"
   exit 0
 else
-  exit 100
+  exit 1
 fi

buildpack.toml

@@ -1,10 +1,5 @@
-api = "0.2"
-
 [buildpack]
-id = "heroku/ruby"
-version = "0.1.4"
 name = "Ruby"
-homepage = "https://github.com/heroku/heroku-buildpack-ruby"
 ruby_version = "3.1.4"
 
 [publish]
@@ -19,7 +14,6 @@ files = [
   "app.json",
   "hatchet.json",
   "hatchet.lock",
-  "package.toml",
 ]
 
 [[publish.Vendor]]
@@ -33,16 +27,3 @@ dir = "vendor/ruby/heroku-22"
 [[publish.Vendor]]
 url = "https://heroku-buildpack-ruby.s3.us-east-1.amazonaws.com/heroku-24/amd64/ruby-3.1.4.tgz"
 dir = "vendor/ruby/amd64/heroku-24"
-
-[[stacks]]
-id = "heroku-20"
-
-[[stacks]]
-id = "heroku-22"
-
-[metadata]
-
-[metadata.release]
-
-[metadata.release.docker]
-repository = "public.ecr.aws/heroku-buildpacks/heroku-ruby-buildpack"

lib/language_pack/base.rb

@@ -5,7 +5,6 @@
 require "language_pack/shell_helpers"
 require "language_pack/cache"
 require "language_pack/helpers/bundler_cache"
-require "language_pack/helpers/layer"
 require "language_pack/metadata"
 require "language_pack/fetcher"
 
@@ -28,15 +27,14 @@ class LanguagePack::Base
   # changes directory to the build_path
   # @param [String] the path of the build dir
   # @param [String] the path of the cache dir this is nil during detect and release
-  def initialize(build_path, cache_path = nil, layer_dir=nil)
+  def initialize(build_path, cache_path = nil)
     @build_path    = build_path
     @stack         = ENV.fetch("STACK")
     @cache         = LanguagePack::Cache.new(cache_path)
     @metadata      = LanguagePack::Metadata.new(@cache)
     @bundler_cache = LanguagePack::BundlerCache.new(@cache, @stack)
     @id            = Digest::SHA1.hexdigest("#{Time.now.to_f}-#{rand(1000000)}")[0..10]
     @fetchers      = {:buildpack => LanguagePack::Fetcher.new(VENDOR_URL) }
-    @layer_dir     = layer_dir
     @arch = get_arch
 
     Dir.chdir build_path
@@ -103,24 +101,6 @@ def compile
     mcount "success"
   end
 
-  def build
-    write_release_toml
-    Kernel.puts ""
-    warnings.each do |warning|
-      Kernel.puts "\e[1m\e[33m###### WARNING:\e[0m"# Bold yellow
-      Kernel.puts ""
-      puts warning
-      Kernel.puts ""
-      Kernel.puts ""
-    end
-    if deprecations.any?
-      topic "DEPRECATIONS:"
-      puts @deprecations.join("\n")
-    end
-    Kernel.puts ""
-    mcount "success"
-  end
-
   def build_release
     release = {}
     release["addons"]                = default_addons
@@ -130,29 +110,6 @@ def build_release
     release
   end
 
-  def write_release_toml
-    release = build_release
-
-    layer = LanguagePack::Helpers::Layer.new(@layer_dir, "env", launch: true)
-    FileUtils.mkdir_p("#{layer.path}/env.launch")
-    release["config_vars"].each do |key, value|
-      File.open("#{layer.path}/env.launch/#{key.upcase}.override", 'w') do |f|
-        f.write(value)
-      end
-    end
-
-    release_toml = release["default_process_types"].map do |type, command|
-      <<PROCESSES
-[[processes]]
-type = "#{type}"
-command = "#{command}"
-PROCESSES
-    end
-    File.open("#{@layer_dir}/launch.toml", 'a') do |f|
-      f.write(release_toml.join("\n"))
-    end
-  end
-
   def write_release_yaml
     release = build_release
     FileUtils.mkdir("tmp") unless File.exists?("tmp")
@@ -163,11 +120,6 @@ def write_release_yaml
     warn_webserver
   end
 
-  # write out the release. Pick v2a or v3 release format
-  def write_release
-    @layer_dir ? write_release_toml : write_release_yaml
-  end
-
   def warn_webserver
     return if File.exist?("Procfile")
     msg =  "No Procfile detected, using the default web server.\n"
@@ -209,7 +161,7 @@ def setup_language_pack_environment
   end
 
   def add_to_profiled(string, filename: "ruby.sh", mode: "a")
-    profiled_path = @layer_dir ? "#{@layer_dir}/ruby/profile.d/" : "#{build_path}/.profile.d/"
+    profiled_path = "#{build_path}/.profile.d/"
 
     FileUtils.mkdir_p profiled_path
     File.open("#{profiled_path}/#{filename}", mode) do |file|
@@ -234,51 +186,32 @@ def add_to_export(string)
 
   # option can be :path, :default, :override
   # https://github.com/buildpacks/spec/blob/366ac1aa0be59d11010cc21aa06c16d81d8d43e7/buildpack.md#environment-variable-modification-rules
-  def export(key, val, layer: nil, option: nil)
-    if layer
-      # don't replace if the key is already set
-      return if ENV[key] && option == :default
-
-      filename =
-        if option.nil? || option == :path
-          key
-        elsif option == :default
-          "#{key}.override"
-        else
-          "#{key}.#{option}"
-        end
-
-      FileUtils.mkdir_p("#{layer.path}/env.build")
-      File.open("#{layer.path}/env.build/#{filename}", "w") do |f|
-        f.write(val)
-      end
-    else
-      string =
-        if option == :default
-          %{export #{key}="${#{key}:-#{val}}"}
-        elsif option == :path
-          %{export #{key}="#{val}:$#{key}"}
-        else
-          %{export #{key}="#{val.gsub('"','\"')}"}
-        end
-
-      export = File.join(ROOT_DIR, "export")
-      File.open(export, "a") do |file|
-        file.puts string
+  def export(key, val, option: nil)
+    string =
+      if option == :default
+        %{export #{key}="${#{key}:-#{val}}"}
+      elsif option == :path
+        %{export #{key}="#{val}:$#{key}"}
+      else
+        %{export #{key}="#{val.gsub('"','\"')}"}
       end
+
+    export = File.join(ROOT_DIR, "export")
+    File.open(export, "a") do |file|
+      file.puts string
     end
   end
 
-  def set_export_default(key, val, layer = nil)
-    export key, val, layer: layer, option: :default
+  def set_export_default(key, val)
+    export key, val, option: :default
   end
 
-  def set_export_override(key, val, layer = nil)
-    export key, val, layer: layer, option: :override
+  def set_export_override(key, val)
+    export key, val, option: :override
   end
 
-  def set_export_path(key, val, layer = nil)
-    export key, val, layer: layer, option: :path
+  def set_export_path(key, val)
+    export key, val, option: :path
   end
 
   def log_internal(*args)

lib/language_pack/rails2.rb

@@ -55,12 +55,6 @@ def compile
     super
   end
 
-  def build
-    # TODO install plugins into separate layer
-    install_plugins
-    super
-  end
-
   def best_practice_warnings
     if env("RAILS_ENV") != "production"
       warn(<<-WARNING)