[FEATURE] bundle_install rule publishes individual gems

Author: graham jenson

ruby/private/bundle/BUILD.bundle.tpl

@@ -15,41 +15,54 @@ def _get_bundler_lib_label(repository_ctx, ruby_sdk):
 def bundle_install_impl(ctx):
   ctx.symlink(ctx.attr.gemfile, "Gemfile")
   ctx.symlink(ctx.attr.gemfile_lock, "Gemfile.lock")
+  ctx.symlink(ctx.attr._create_bundle_build_file, "create_bundle_build_file.rb")
 
   ruby = _get_interpreter_label(ctx, ctx.attr.ruby_sdk)
   bundler = _get_bundler_label(ctx, ctx.attr.ruby_sdk)
 
+  # Install the Gems into the workspace
   args = [
-      'env', '-i',
-      ctx.path(ruby),
-      '--disable-gems',
-      '-I', ctx.path(bundler).dirname.dirname.get_child('lib'),
-      ctx.path(bundler),
-      'install',
-      '--deployment',
-      '--standalone',
-      '--frozen',
-      '--binstubs=bin',
-      '--path=lib',
+      'env', '-i',                                              # remove all environment variables
+      ctx.path(ruby),                                           # ruby
+      '--disable-gems',                                         # prevent the addition of gem installation directories to the default load path
+      '-I', ctx.path(bundler).dirname.dirname.get_child('lib'), # Used to tell Ruby where to load the library scripts
+      ctx.path(bundler),                                        # execute bundler
+      'install',                                                # install
+      '--deployment',                                           # In deployment mode, Bundler will 'roll-out' the bundle for production or CI use.
+      '--standalone',                                           # Makes a bundle that can work without depending on Rubygems or Bundler at runtime.
+      '--frozen',                                               # Do not allow the Gemfile.lock to be updated after this install.
+      '--binstubs=bin',                                         # Creates a directory and place any executables from the gem there.
+      '--path=lib',                                             # The location to install the specified gems to.
   ]
   result = ctx.execute(args, quiet=False)
+
   if result.return_code:
     fail("Failed to install gems: %s%s" % (result.stdout, result.stderr))
 
+  # exclude any specified files
   exclude = []
   for gem, globs in ctx.attr.excludes.items():
     expanded = ["lib/ruby/*/gems/%s-*/%s" % (gem, glob) for glob in globs]
     exclude.extend(expanded)
 
-  ctx.template(
+  # Create the BUILD file to expose the gems to the WORKSPACE
+  args = [
+      'env', '-i',                                              # remove all environment variables
+      ctx.path(ruby),                                           # ruby
+      '--disable-gems',                                         # prevent the addition of gem installation directories to the default load path
+      '-I', ctx.path(bundler).dirname.dirname.get_child('lib'), # Used to tell Ruby where to load the library scripts
+      'create_bundle_build_file.rb',
       'BUILD.bazel',
-      ctx.attr._buildfile_template,
-      substitutions = {
-          "{repo_name}": ctx.name,
-          "{exclude}": repr(exclude),
-          "{workspace_name}": RULES_RUBY_WORKSPACE_NAME,
-      },
-  )
+      'Gemfile.lock',
+      ctx.name,
+      repr(exclude),
+      RULES_RUBY_WORKSPACE_NAME,
+
+  ]
+  result = ctx.execute(args, quiet=False)
+
+  if result.return_code:
+    fail("Failed to create build file: %s%s" % (result.stdout, result.stderr))
 
 
 bundle_install = repository_rule(
@@ -68,10 +81,10 @@ bundle_install = repository_rule(
             doc = "List of glob patterns per gem to be excluded from the library",
         ),
 
-        "_buildfile_template": attr.label(
-            default = "%s//ruby/private/bundle:BUILD.bundle.tpl" % (
+        "_create_bundle_build_file": attr.label(
+            default = "%s//ruby/private/bundle:create_bundle_build_file.rb" % (
                 RULES_RUBY_WORKSPACE_NAME),
-            doc = "The template of BUILD files for installed gem bundles",
+            doc = "Creates the BUILD file",
             allow_single_file = True,
         ),
     },

ruby/private/bundle/bundle.bzl

@@ -0,0 +1,113 @@
+TEMPLATE = 'load(
+  "{workspace_name}//ruby:defs.bzl",
+  "ruby_library",
+)
+
+package(default_visibility = ["//visibility:public"])
+
+filegroup(
+  name = "binstubs",
+  srcs = glob(["bin/**/*"]),
+  data = [":libs"],
+)
+
+ruby_library(
+  name = "bundler_setup",
+  srcs = ["lib/bundler/setup.rb"],
+  visibility = ["//visibility:private"],
+)
+
+# DEPRECATED: use :all instead
+ruby_library(
+  name = "libs",
+  srcs = glob(
+    include = [
+      "lib/ruby/{ruby_version}/gems/*/**/*",
+      "lib/ruby/{ruby_version}/bin/**/*",
+    ],
+    exclude = {exclude},
+  ),
+  deps = [":bundler_setup"],
+  rubyopt = ["-r../{repo_name}/lib/bundler/setup.rb"],
+)
+
+# PULL EACH GEM INDIVIDUALLY
+'
+
+GEM_TEMPLATE = '
+ruby_library(
+  name = "{name}",
+  srcs = glob(
+    include = [
+      "lib/ruby/{ruby_version}/gems/{name}-{version}/**/*",
+      # TODO scope down included bin files
+      "lib/ruby/{ruby_version}/bin/**/*",
+    ],
+    exclude = {exclude},
+  ),
+  deps = {deps},
+  rubyopt = ["-r../{repo_name}/lib/bundler/setup.rb"],
+)
+
+'
+
+ALL_TEMPLATE = '
+ruby_library(
+  name = "all",
+  deps = {deps},
+  rubyopt = ["-r../{repo_name}/lib/bundler/setup.rb"],
+)
+'
+require "bundler"
+
+def create_bundle_build_file(build_out_file, lock_file, repo_name, excludes, workspace_name)
+	# TODO: properly calculate path/ruby version here
+	# ruby_version = RUBY_VERSION # doesnt work because verion is 2.5.5 path is 2.5.0
+	ruby_version = "*"
+
+	template_out = TEMPLATE.gsub("{workspace_name}", workspace_name)
+												 .gsub("{exclude}", excludes)
+												 .gsub("{repo_name}", repo_name)
+												 .gsub("{ruby_version}", ruby_version)
+
+
+
+  # Append to the end specific gem libraries and dependencies
+	bundle = Bundler::LockfileParser.new(Bundler.read_file(lock_file))
+
+	bundle.specs.each { |spec|
+	  	deps = spec.dependencies.map{ |d| d.name }
+	  	deps += [":bundler_setup"]
+	  	template_out += GEM_TEMPLATE.gsub("{exclude}", excludes)
+	  															.gsub("{name}", spec.name)
+	  															.gsub("{version}", spec.version.to_s)
+	  															.gsub("{deps}", deps.to_s)
+																  .gsub("{repo_name}", repo_name)
+																  .gsub("{ruby_version}", ruby_version)
+	}
+
+	# Append collection of all gems
+	template_out += ALL_TEMPLATE.gsub("{repo_name}", repo_name)
+															.gsub("{deps}", ([":bundler_setup"] + bundle.specs.map{ |s| s.name }).to_s)
+
+	# Write the actual BUILD file
+	open(build_out_file, 'w') { |f|
+  	f.puts template_out
+  }
+end
+
+# ruby ./create_bundle_build_file.rb "BUILD.bazel" "Gemfile.lock" "repo_name" "[]" "wsp_name"
+if $0 == __FILE__
+	if ARGV.length != 5
+		fmt.Println("BUILD FILE ARGS not 5")
+		exit(1)
+	end
+
+	build_out_file = ARGV[0]
+	lock_file = ARGV[1]
+	repo_name = ARGV[2]
+	excludes = ARGV[3]
+	workspace_name = ARGV[4]
+
+  create_bundle_build_file(build_out_file, lock_file, repo_name, excludes, workspace_name)
+end