Add options to daemonize puma

Previously I was opposed to these options because I felt like puma
should always be run under another monitoring process. But after doing
some thinking (and some deployment of puma) I realized that the daemon
option is simply too useful to not include.

I highly suggest it be used with -w, so that if a worker crashes the
whole server doesn't mysteriously disappear.

lib/puma/cli.rb

@@ -6,6 +6,7 @@ require 'puma/const'
 require 'puma/configuration'
 require 'puma/binder'
 require 'puma/detect'
+require 'puma/daemon_ext'
 
 require 'rack/commonlogger'
 require 'rack/utils'
@@ -159,7 +160,8 @@ module Puma
         :quiet => false,
         :debug => false,
         :binds => [],
-        :workers => 0
+        :workers => 0,
+        :daemon => false
       }
 
       @parser = OptionParser.new do |o|
@@ -171,6 +173,15 @@ module Puma
           @options[:config_file] = arg
         end
 
+        o.on "-d", "--daemon", "Daemonize the server into the background" do
+          @options[:daemon] = true
+          @options[:quiet] = true
+        end
+
+        o.on "--dir DIR", "Change to DIR before starting" do |d|
+          @options[:directory] = d.to_s
+        end
+
         o.on "-I", "--include PATH", "Specify $LOAD_PATH directories" do |arg|
           $LOAD_PATH.unshift(*arg.split(':'))
         end
@@ -321,6 +332,10 @@ module Puma
         exit 1
       end
 
+      if dir = @options[:directory]
+        Dir.chdir dir
+      end
+
       clustered = @options[:workers] > 0
 
       if clustered
@@ -407,7 +422,11 @@ module Puma
         log "*** Sorry signal SIGTERM not implemented, gracefully stopping feature disabled!"
       end
 
-      log "Use Ctrl-C to stop"
+      if @options[:daemon]
+        Process.daemon(true)
+      else
+        log "Use Ctrl-C to stop"
+      end
 
       begin
         server.run.join
@@ -538,9 +557,15 @@ module Puma
       #
       @check_pipe, @suicide_pipe = IO.pipe
 
-      spawn_workers
+      if @options[:daemon]
+        Process.daemon(true)
+        STDOUT.reopen "/tmp/puma.out", "a"
+        STDOUT.reopen "/tmp/puma.err", "a"
+      else
+        log "Use Ctrl-C to stop"
+      end
 
-      log "* Use Ctrl-C to stop"
+      spawn_workers
 
       begin
         while !stop

lib/puma/configuration.rb

@@ -156,6 +156,12 @@ module Puma
         @options[:binds] << url
       end
 
+      # Daemonize the server into the background. Highly suggest that
+      # this be combined with +pidfile+ and +stdout_redirect+.
+      def daemonize(which=true)
+        @options[:daemon] = which
+      end
+
       # Set the environment in which the Rack's app will run.
       def environment(environment)
         @options[:environment] = environment
@@ -187,6 +193,17 @@ module Puma
         @options[:rackup] = path.to_s
       end
 
+      # Redirect STDOUT and STDERR to files specified.
+      def stdout_redirect(stdout=nil, stderr=nil, append=false)
+        if stdout
+          STDOUT.reopen stdout, (append ? "a" : "w")
+        end
+
+        if stderr
+          STDOUT.reopen stderr, (append ? "a" : "w")
+        end
+      end
+
       # Configure +min+ to be the minimum number of threads to use to answer
       # requests and +max+ the maximum.
       #
@@ -220,6 +237,11 @@ module Puma
       def workers(count)
         @options[:workers] = count.to_i
       end
+
+      # The directory to operate out of.
+      def directory(dir)
+        @options[:directory] = dir.to_s
+      end
     end
   end
 end

lib/puma/daemon_ext.rb

@@ -0,0 +1,20 @@
+module Process
+  def self.daemon(nochdir=false, noclose=false)
+    exit if fork                     # Parent exits, child continues.
+
+    Process.setsid                   # Become session leader.
+
+    exit if fork                     # Zap session leader. See [1].
+
+    Dir.chdir "/" unless nochdir     # Release old working directory.
+
+    if !noclose
+      null = File.open "/dev/null"
+      STDIN.reopen null
+      STDOUT.reopen null
+      STDERR.reopen null
+    end
+
+    0
+  end unless respond_to?(:daemon)
+end