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Rails Servers with Unicorn and Nginx

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Final Touches to Nginx Configuration

3:47 with Jay McGavren

We're still getting "The change you wanted was rejected" errors when we try to submit a form. This is because Nginx isn't forwarding all the headers in the requests it receives to Unicorn. Let's fix that now, in addition to setting a few more important configuration items.

The new Nginx configuration items shown in this video were copied from the Unicorn project's sample Nginx configuration.

Our final config/nginx.conf contents:

upstream unicorn {
  server unix:/tmp/unicorn.guestbook.sock fail_timeout=0;
}

server {
  client_max_body_size 4G;
  listen 80 default;
  root /home/deploy/guestbook/public;
  try_files $uri/index.html $uri @unicorn;
  location @unicorn {
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $http_host;
    proxy_redirect off;
    proxy_pass http://unicorn;
  }
  error_page 500 502 503 504 /500.html;
}

Our final config/unicorn.rb contents:

pid "/home/deploy/guestbook/pids/unicorn.pid"
stderr_path "/home/deploy/guestbook/unicorn/unicorn.log"
stdout_path "/home/deploy/guestbook/unicorn/unicorn.log"

listen "/tmp/unicorn.guestbook.sock"
worker_processes 2
timeout 30

Be sure to run sudo service nginx restart after updating nginx.conf. Once you do, you should be able to visit your app and submit forms.

Further Reading

Nginx site

Unicorn site

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    We still have one more problem because Engine X isn't forwarding all the headers 0:00
    for our http request on to Unicorn. 0:04
    Any time we try to submit a form the authenticity token isn't clearing and 0:07
    we get an error the change you wanted was rejected. 0:12
    So next we're going to need to fix that. 0:15
    Within the unicorn source free sample configuration for engine X. 0:18
    We can copy the configuration settings we need, out of this. 0:23
    We'll have the link in the teacher's notes if you want to refer to it yourself. 0:27
    So let's go back into our shell and edit our engine X configuration. 0:31
    And we'll just go through the sample configuration file and 0:40
    copy over the relevant settings. 0:43
    The relevant ones will be down here in the server directive. 0:52
    And the first will more going to want to copy over is this client Max 0:57
    body size setting, this will allow us to 1:00
    accept large attachments if a client submit one via the form. 1:03
    So I'll copy that out of there, go back to our terminal and 1:08
    here within the server directive, I'll paste it here. 1:11
    Next step is the server_name directive. 1:20
    If our app had a domain name, 1:23
    we'd want to enter that here as myapp.com, whatever that might be. 1:24
    We don't have that at present though so I'm going to go and leave that line out. 1:29
    Okay. These next settings within the location 1:36
    app directive should forward the headings on from Engine X. 1:39
    to unicorn that is they should fix our issue with form submissions So, 1:42
    we're gonna copy these out and start with proxy said header x_forwarded_for. 1:47
    Just copy that line out of there and we're going to want to add these within 1:53
    the location unicorn directive here and our. 1:57
    And next Conficker piece that in there. 2:00
    Thanks will want to forward the Host header as well I'll copy that out 2:05
    of there. 2:09
    And we'll also copy this proxy redirect setting out of here. 2:15
    So that's everything for the location, your app name directive And 2:25
    after the curly brace that ends that directive there's one more setting 2:29
    we're going to want to copy out as well. 2:33
    We'll copy this error page directive over Again outside of the location directive. 2:38
    And this directive will cause several errors to show the 500 HTML file from your 2:47
    apps public directory instead of an ugly error page from Engine X. 2:52
    Now that we've got all that configuration copied over we're going to write out our 2:56
    file exit and as always we're going to need to restart engine X.. 2:59
    Now let's go back into our app and try to create a new signature. 3:06
    And we're successful this time. 3:14
    All the headers are passed on properly and our authenticity token is accepted. 3:16
    So there you have it engine x is configured to act as a reverse proxy, 3:22
    it forwards web requests on to a unicorn through a Unix socket. 3:26
    It's a stable speedy set up that's ready to serve your users. 3:29
    We had to go through quite a few steps to configure this, so if you ran into trouble 3:34
    check the teacher's notes and compare our final code to yours. 3:38
    Will also have links in the notes where you can get more info on engine X in 3:42
    the unicorn code. 3:45
    Thanks for watching. 3:46

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