feat: support bun as a package manager

.github/workflows/ci.yml

@@ -73,6 +73,8 @@ jobs:
             installer: yarn
           - name: pnpm
             installer: pnpm
+          - name: bun
+            installer: bun
         variant:
           - name: defaults
             config_path: "ackama_rails_template.config.yml"

ci/bin/create-fake-js-package-managers

@@ -30,7 +30,7 @@ elsif system("direnv --version > /dev/null 2>&1")
   system("direnv allow")
 end
 
-managers = %w[npm yarn pnpm]
+managers = %w[npm yarn pnpm bun]
 manager_in_use = ARGV[0] || ""
 
 if manager_in_use.empty?

template.rb

@@ -251,6 +251,16 @@ def setup_yarn_berry
   File.unlink("package.json")
 end
 
+# Bun uses a binary-based lockfile which cannot be parsed by shakapacker or
+# osv-detector, so we want to configure bun to always write a yarn.lock
+# in addition so that such tools can check it
+def setup_bun
+  File.write("bunfig.toml", <<~TOML)
+    [install.lockfile]
+    print = "yarn"
+  TOML
+end
+
 def add_yarn_package_extension_dependency(name, dependency)
   return unless File.exist?(".yarnrc.yml")
 
@@ -267,7 +277,10 @@ def add_yarn_package_extension_dependency(name, dependency)
 end
 
 def package_json
-  setup_yarn_berry if @package_json.nil? && ENV.fetch("PACKAGE_JSON_FALLBACK_MANAGER", nil) == "yarn_berry"
+  if @package_json.nil?
+    setup_yarn_berry if ENV.fetch("PACKAGE_JSON_FALLBACK_MANAGER", nil) == "yarn_berry"
+    setup_bun if ENV.fetch("PACKAGE_JSON_FALLBACK_MANAGER", nil) == "bun"
+  end
 
   @package_json ||= PackageJson.new
 end