Rails 4 + nginx + unicorn + ssl = 502 Bad Gateway

Question

Browser is showing 502 Bad Gateway - nginx. The only good news is my SSL https and green lock is showing up. Nginx Logs Error below nginx/error.log ``` *1 connect() failed (111: Connection refused) while connecting to upstream, client: xx.xxx.xx.xx, server: mysite.com, request: "GET / HTTP/1.1", upstream: "http://xxx.xxx.xx.xxx:80/maintenance.html", host: "mysite.com" ``` home/unicorn/log/unicorn.log (seems like it's waiting for nginx): ``` I, [2014-01-28T17:18:37.176299 #31858] INFO -- : listening on addr=127.0.0.1:8080 fd=10 I, [2014-01-28T17:18:37.176619 #31858] INFO -- : worker=0 spawning... I, [2014-01-28T17:18:37.177379 #31858] INFO -- : worker=1 spawning... I, [2014-01-28T17:18:37.178118 #31858] INFO -- : master process ready I, [2014-01-28T17:18:37.182850 #31861] INFO -- : worker=0 spawned pid=31861 I, [2014-01-28T17:18:37.185475 #31863] INFO -- : worker=1 spawned pid=31863 I, [2014-01-28T17:18:37.186023 #31861] INFO -- : Refreshing Gem list I, [2014-01-28T17:18:37.194198 #318…

Accepted Answer

The problem is that Unicorn and Nginx do not agree on a shared socket. Also, in the files you have posted, the `upstream` and `proxy_pass` do not match. How about:

In the `server` context:

```
location @unicorn {
  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
  proxy_set_header X-Forwarded-Proto https;
  proxy_set_header Host $http_host;
  proxy_redirect off;
  proxy_pass http://unicorn_server; # This name must match the upstream
}
```

In the `http` context:

```
upstream unicorn_server {
  server unix:/var/run/my_site/unicorn.sock;
}
```

In the Unicorn configuration file (here `/home/unicorn/unicorn.conf`):

```
listen '/var/run/my_site/unicorn.sock', :backlog => 64
```

Note Unicorn listens on a socket where Nginx posts requests.

Rails 4 + nginx + unicorn + ssl = 502 Bad Gateway

Solution

Problem