start libifying common launcher code

The daemonization logic between unicorn and unicorn_rails
scripts can definitely be shared.

Again: our daemonization logic is slightly non-standard since
our executables are designed to run in APP_ROOT/RAILS_ROOT and
not "/" like "normal" UNIX daemons.

1 files changed, 33 insertions, 0 deletions

diff --git a/lib/unicorn/launcher.rb b/lib/unicorn/launcher.rb
new file mode 100644
index 0000000..8c96059
--- /dev/null
+++ b/lib/unicorn/launcher.rb
@@ -0,0 +1,33 @@
+$stdin.sync = $stdout.sync = $stderr.sync = true
+require 'unicorn'
+
+class Unicorn::Launcher
+
+  # We don't do a lot of standard daemonization stuff:
+  #   * umask is whatever was set by the parent process at startup
+  #     and can be set in config.ru and config_file, so making it
+  #     0000 and potentially exposing sensitive log data can be bad
+  #     policy.
+  #   * don't bother to chdir("/") here since unicorn is designed to
+  #     run inside APP_ROOT.  Unicorn will also re-chdir() to
+  #     the directory it was started in when being re-executed
+  #     to pickup code changes if the original deployment directory
+  #     is a symlink or otherwise got replaced.
+  def self.daemonize!
+    $stdin.reopen("/dev/null")
+
+    # We only start a new process group if we're not being reexecuted
+    # and inheriting file descriptors from our parent
+    unless ENV['UNICORN_FD']
+      exit if fork
+      Process.setsid
+      exit if fork
+
+      # $stderr/$stderr can/will be redirected separately in the Unicorn config
+      $stdout.reopen("/dev/null", "a")
+      $stderr.reopen("/dev/null", "a")
+    end
+    $stdin.sync = $stdout.sync = $stderr.sync = true
+  end
+
+end