Allow extra runtime deps to be defined when using prune_bundler

examples/config.rb

@@ -158,6 +158,11 @@
 
 # prune_bundler
 
+# Extra gems to be loaded when the environment bundler context is pruned.
+# Only applies if prune_bundler is used.
+
+# extra_runtime_dependencies ['gem_name_1', 'gem_name_2']
+
 # Preload the application before starting the workers; this conflicts with
 # phased restart feature. (off by default)
 

lib/puma/cli.rb

@@ -159,6 +159,10 @@ def setup_options
             user_config.prune_bundler
           end
 
+          o.on "--extra-runtime-dependencies GEM1,GEM2", "Defines any extra needed gems when using --prune-bundler" do |arg|
+            c.extra_runtime_dependencies arg.split(',')
+          end
+
           o.on "-q", "--quiet", "Do not log requests internally (default true)" do
             user_config.quiet
           end

lib/puma/dsl.rb

@@ -414,6 +414,15 @@ def prune_bundler(answer=true)
       @options[:prune_bundler] = answer
     end
 
+    # When using prune_bundler, if extra runtime dependencies need to be loaded to
+    # initialize your app, then this setting can be used.
+    #
+    # For each gem's name passed, that gem will be loaded when the environment
+    # is pruned.
+    def extra_runtime_dependencies(answer = [])
+      @options[:extra_runtime_dependencies] = Array(answer)
+    end
+
     # Additional text to display in process listing
     def tag(string)
       @options[:tag] = string.to_s

lib/puma/launcher.rb

@@ -262,6 +262,15 @@ def prune_bundler
         "#{d.name}:#{spec.version.to_s}"
       end
 
+      @options[:extra_runtime_dependencies].each do |d_name|
+        spec = Bundler.rubygems.loaded_specs(d_name) rescue nil
+        if spec
+          deps << "#{d_name}:#{spec.version.to_s}"
+        else
+          log "* Couldn't to load extra dependency: #{d_name}"
+        end
+      end
+
       log '* Pruning Bundler environment'
       home = ENV['GEM_HOME']
       Bundler.with_clean_env do