unicorn/reexec/bundler/cap deploy issue

[skaar <skaar@waste.org>]

Hi Eric,

we've run into an issue with Unicorn's reexec, when the rails app is
using Bundler and we deploy into dated release directories. Still not
sure what the correct fix is for this, but what happens is that bundler
modifies (acutally prefixes) PATH/RUBYOPT and when you reexec unicorn
these are passed along to the new master process - and Bundler will
again append to the PATH/RUBYOBT.

This becomes more of a problem when you deploy with capistrano and
include SIGUSR2 restart of your unicorn. And effectively it will attempt
to load all Bundler vendor/bundler_gems/environment.rb for all deploys
since unicorn was first started - and if you have, say, a keep only 5
releases strategy, you will soon get failures when a bundler
environment.rb file in RUBYOPT has been shifted out.

I'm still not sure what the right solution is (to modify unicorn, the
unicorn.rb config file or to address it in bundler), but the following
patch does it brute force in unicorn and introduce the assumption that
a reexec should take the same PATH/RUBYOPT variables as the initial
invokation of the unicorn process (using a similar strategy as with
PWD):


>From 3d6ca163723148668d69115ebaf00cb814db8f49 Mon Sep 17 00:00:00 2001
From: skaar <skaar@waste.org>
Date: Sat, 2 Jan 2010 12:29:38 -0500
Subject: [PATCH] filter PATH/RUBYOPT when rexec, and give new master same values as the
 original master process

---
 lib/unicorn.rb |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/lib/unicorn.rb b/lib/unicorn.rb
index 225e00a..6b3e334 100644
--- a/lib/unicorn.rb
+++ b/lib/unicorn.rb
@@ -111,6 +111,8 @@ module Unicorn
             Dir.pwd
           end
         }.call,
+      :path => ENV['PATH'],
+      :rybyopt => ENV['RUBYOPT'],
       0 => $0.dup,
     }
 
@@ -488,6 +490,8 @@ module Unicorn
       self.reexec_pid = fork do
         listener_fds = LISTENERS.map { |sock| sock.fileno }
         ENV['UNICORN_FD'] = listener_fds.join(',')
+        ENV['PATH'] = START_CTX[:path]
+        ENV['RUBYOPT'] = START_CTX[:rubyopt]
         Dir.chdir(START_CTX[:cwd])
         cmd = [ START_CTX[0] ].concat(START_CTX[:argv])
 
-- 
1.6.6.rc3



-- 
/skaar

skaar@waste.org
where in the W.A.S.T.E is the wisdom
s_u_b_s_t_r_u_c_t_i_o_n
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