Passenger + Nginx => 502 Bad Gateway

Question

I'm trying to run a relatively simple rails app (http:// www.enkiblog.com/) and it kinda works. The comments and the admin interface only work when I use "script/ server -e production" and connect to Port 3000 (still in production mode though).

Nginx will have this in his error.log:

2009/06/02 21:46:10 [error] 11536#0: *18 upstream prematurely closed
connection while reading response header from upstream, client:
85.180.23.43, server: *.marc-seeger.de, request: "GET /admin HTTP/
1.1", upstream: "unix:/tmp/passenger.11520/master/
helper_server.sock:", host: "www.marc-seeger.de"
*** Exception NoMethodError in application (undefined method `each'
for nil:NilClass) (process 14080):
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/rack/request_handler.rb:
85:in `process_request'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/abstract_request_handler.rb:
203:in `main_loop'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/railz/
application_spawner.rb:340:in `start_request_handler'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/railz/
application_spawner.rb:298:in `handle_spawn_application'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/utils.rb:181:in `safe_fork'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/railz/
application_spawner.rb:296:in `handle_spawn_application'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/abstract_server.rb:337:in
`__send__'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/abstract_server.rb:337:in
`main_loop'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/abstract_server.rb:187:in
`start_synchronously'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/abstract_server.rb:154:in
`start'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/railz/
application_spawner.rb:192:in `start'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/spawn_manager.rb:257:in
`spawn_rails_application'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/
abstract_server_collection.rb:126:in `lookup_or_add'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/spawn_manager.rb:251:in
`spawn_rails_application'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/
abstract_server_collection.rb:80:in `synchronize'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/
abstract_server_collection.rb:79:in `synchronize'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/spawn_manager.rb:250:in
`spawn_rails_application'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/spawn_manager.rb:153:in
`spawn_application'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/spawn_manager.rb:282:in
`handle_spawn_application'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/abstract_server.rb:337:in
`__send__'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/abstract_server.rb:337:in
`main_loop'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/lib/phusion_passenger/abstract_server.rb:187:in
`start_synchronously'
        from /opt/ruby-enterprise-1.8.6-20090421/lib/ruby/gems/1.8/
gems/passenger-2.2.2/bin/passenger-spawn-server:61
Error during failsafe response: closed stream

Any idea?

p.s. debian 5.0

Solution 1

Turns out it was a passenger + sqlite + nginx + unix permissions problem.
I "solved" it by migrating to MySQL

Solution 2

You can get a 502 error like this from nginx when you don't have the proper permissions set on an SQLite database.

Comments

[Admin]

I'm having this same issue although not using SQLite - the problem only started when I upgraded to Rails 3.1. Any suggestions as to why>

[Admin]

asset pipeline is my first suspect

[Admin]

For me it was the SQLite permissions

[Admin]

seems there's a bug with the latest Rails 3.1 release candidate. Enabling threadsafe mode solves this in the short-term but it's a rack issue

[rb2k]

As I mentioned in my answer, that actually was the solution :) It seems to have something to do with the permissions passenger uses to spawn the interpreter threads. I tried basically anything but I couldn't chmod my way out of this