Fix Xcode 8 hung-up by making Helper.backticks retriable

.rubocop.yml

@@ -79,6 +79,8 @@ Style/AndOr:
 Metrics/ClassLength:
   Max: 320
 
+Metrics/ModuleLength:
+  Max: 130
 
 # Configuration parameters: AllowURI, URISchemes.
 Metrics/LineLength:

fastlane_core/fastlane_core.gemspec

@@ -31,6 +31,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'plist', '~> 3.1' # needed for parsing provisioning profiles
   spec.add_dependency 'terminal-table', '~> 1.4.5' # options summary
   spec.add_dependency 'gh_inspector', '>= 1.0.1', '< 2.0.0' # search for issues on GitHub when something goes wrong
+  spec.add_dependency 'retriable', '~> 2.1' # simple DSL to retry failed code blocks
 
   spec.add_dependency 'credentials_manager', '>= 0.16.0', '< 1.0.0' # fastlane password manager
 

fastlane_core/lib/fastlane_core/helper.rb

@@ -12,11 +12,34 @@ def self.log
 
     # Runs a given command using backticks (`)
     # and prints them out using the UI.command method
-    def self.backticks(command, print: true)
-      UI.command(command) if print
-      result = `#{command}`
-      UI.command_output(result) if print
-      return result
+    def self.backticks(command, print: true, retriable_options: {})
+      require 'retriable'
+      tries = retriable_options[:tries] || 1
+      timeout = retriable_options[:timeout] || 3600
+      on_retry = proc do |exception, try, elapsed_time, next_interval|
+        if try < tries
+          UI.important("#{exception.class}: '#{exception.message}' - #{try} tries in #{elapsed_time} seconds and #{next_interval.to_i} seconds until the next try.")
+        end
+      end
+
+      options = {
+        on: Timeout::Error,
+        tries: tries,
+        timeout: timeout,
+        base_interval: 0,
+        on_retry: on_retry
+      }
+
+      begin
+        Retriable.retriable(options) do
+          UI.command(command) if print
+          result = `#{command}`
+          UI.command_output(result) if print
+          return result
+        end
+      rescue
+        UI.user_error!("Failed to execute: #{command}")
+      end
     end
 
     # @return true if the currently running program is a unit test

fastlane_core/lib/fastlane_core/project.rb

@@ -216,7 +216,14 @@ def build_xcodebuild_showbuildsettings_command
     def build_settings(key: nil, optional: true)
       unless @build_settings
         command = build_xcodebuild_showbuildsettings_command
-        @build_settings = Helper.backticks(command, print: false)
+        # Workaround for Xcode 8 problem:
+        # `xcodebuild -showBuildSettings` will hang up sometimes
+        # By retrying with specific timeout, this problem can be avoided
+        options = {
+          tries:  (ENV['FASTLANE_XCODEBUILD_SETTINGS_TRIES'] || 3).to_i,
+          timeout: (ENV['FASTLANE_XCODEBUILD_SETTINGS_TIMEOUT'] || 10).to_i
+        }
+        @build_settings = Helper.backticks(command, print: false, retriable_options: options)
       end
 
       begin