Rails5 Action Cable Nginx 404 and 502 errors - ruby-on-rails

Question

Everyone :).
I know people have already faced alot of problems related to mine. I have tried all but my issue has not been resolved. I have been working from past 3 days to fix this but I am unable to do it.
I am using ActionCable for the first time and on development server it is working fine. But in production where I am using Puma and Nginx I am facing terrible issues.
Initially when I had not (location /cable) settings in nginx configuration, server gives me 404 handshake error
i.e Error during WebSocket handshake: Unexpected response code: 404
Then after I add following location /cable configuration in nginx configuration I start getting 502 bad gateway error.
Note: I have not opened any port specifically for ActionCable. I assume it is not required. only port 80 is open on my server.
I need some expert to help me with this. I need quick help to get it fixed. Thanks in advance :)
I have these two lines present in my environment/production.rb
config.action_cable.url = "ws://my_linode_domain/cable"
config.action_cable.allowed_request_origins = [/http:\/\/*/, /https:\/\/*/]
This is my nginx config file
upstream app {
# Path to Puma SOCK file, as defined previously
server unix:/home/deploy/artcrate/shared/tmp/sockets/puma.sock fail_timeout=0;
}
server {
listen 80;
#server_name localhost;
server_name my_linode_domain
# prevents 502 bad gateway error
large_client_header_buffers 8 32k;
root /home/deploy/artcrate/current/public;
try_files $uri/index.html $uri #app;
location / {
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Host $host;
proxy_redirect off;
proxy_http_version 1.1;
proxy_set_header Connection '';
proxy_pass http://app;
}
location ~ ^/(assets|fonts|system)/|favicon.ico|robots.txt {
gzip_static on;
expires max;
add_header Cache-Control public;
}
location /cable{
proxy_pass http://app;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "Upgrade";
}
error_page 500 502 503 504 /500.html;
client_max_body_size 4G;
keepalive_timeout 10;
}
I have tried various proxy_pass options in location /cable settings but none worked.

Answer 1

Everyone. :)
After a week of struggle, hardwork and constantly playing around with nginx and puma configuration files and keenly reading blogs again and again, I was able to figure out the issue.
My nginx configurations were correct. I had to add two more lines to puma.rb configuration which don't come with default configurations. Those two lines are:
workers 2
daemonize true
daemonize true: this tells puma to run in the background by spawning a subprocess and detaching it from the executing shell. If you don't use daemonize, you need to run the puma process via nohup and put it in the background explicitly.
I am not sure if I required workers 2 but I had added them while resolving my issue. So I let it there. But after adding above two lines my ActionCable started to work normally.

Answer 2

RAILS and RUBY version I am using for this project is
Rails 5.0.7
ruby 2.3.1p112
ok. So today I wanted to integrate Action Cable again in my project but faced the same issue again. I applied my above solution but it didn't work. Last time although it worked but I wasn't satisfied with the solution thinking that why would ActionCable work in single thread/worker on local machine.
But this time I focussed and figured out the culprit.
Culprit is NGINX configuration
Configuration when I was facing 404 handshake errors
location /cable {
proxy_pass http://example.com;
proxy_http_version 1.1;
proxy_set_header Upgrade websocket;
proxy_set_header Connection Upgrade;
}
Configuration when all started working fine.
location /cable {
proxy_pass http://puma;
proxy_http_version 1.1;
proxy_set_header Upgrade websocket;
proxy_set_header Connection Upgrade;
}
so the culprit line was:
proxy_pass http://example.com;
Here we are pointing it to NGINX which is wrong, it should point to our puma server path which in my configuration is represented by 'puma'.
Here is the Summary of my implementation of ActionCable and its working copy on Production Server
So to integrate Action Cable with Rails 5 you need to follow following steps:
Setup Redis on default port.
Add these lines in environments/staging.rb or environments/production.rb, depending on your application environment.
config.action_cable.url = [/ws://*/, /wss://*/]
config.action_cable.allowed_request_origins = [/http://*/, /https://*/]
Finally setup you NGINX file as explained above. Here is my complete NGINX configuration in gist nginx.conf. I had replaced my site name with 'example.com' and project name with 'example'. So if you are copying anything, just make sure you replace those with yours otherwise nothing will work as paths will be broken.
I hope this will really release the pain while pushing ActionCable to live application and resolve this handshake error for anyone as this is very very tricky and technical thing and a lot of docs just mention to point action cable to your main site url and not puma server running behind your nginx.
Thanks.