Rails application deployed on Elastic Beanstalk with Puma fails - 502 errors on every request

问题

I just deployed a Rails app to Elastic Beanstalk, and every request is giving me a 502 error.

Here's the contents of /var/logs/nginx/error.log

2015/05/20 16:24:25 [warn] 1535#0: conflicting server name "localhost" on 0.0.0.0:80, ignored
2015/05/20 16:27:12 [crit] 1537#0: *20 connect() to unix:///var/run/puma/my_app.sock failed (2: No such file or directory) while connecting to upstream, client: 172.31.51.94, server: _, request: "POST /get HTTP/1.1", upstream: "http://unix:///var/run/puma/my_app.sock:/get", host: "securities-api-prod.elasticbeanstalk.com"
2015/05/20 16:27:17 [crit] 1537#0: *20 connect() to unix:///var/run/puma/my_app.sock failed (2: No such file or directory) while connecting to upstream, client: 172.31.51.94, server: _, request: "POST /get HTTP/1.1", upstream: "http://unix:///var/run/puma/my_app.sock:/get", host: "securities-api-prod.elasticbeanstalk.com"
2015/05/20 16:27:19 [crit] 1537#0: *20 connect() to unix:///var/run/puma/my_app.sock failed (2: No such file or directory) while connecting to upstream, client: 172.31.51.94, server: _, request: "POST /get HTTP/1.1", upstream: "http://unix:///var/run/puma/my_app.sock:/get", host: "securities-api-prod.elasticbeanstalk.com"
2015/05/20 16:27:22 [crit] 1537#0: *16 connect() to unix:///var/run/puma/my_app.sock failed (2: No such file or directory) while connecting to upstream, client: 172.31.44.210, server: _, request: "GET /datapoint?tickers=AAPL&datapoints=Ratings HTTP/1.1", upstream: "http://unix:///var/run/puma/my_app.sock:/datapoint?tickers=AAPL&datapoints=Ratings", host: "securities-api-prod.elasticbeanstalk.com"
2015/05/20 16:27:27 [crit] 1537#0: *20 connect() to unix:///var/run/puma/my_app.sock failed (2: No such file or directory) while connecting to upstream, client: 172.31.51.94, server: _, request: "POST /get HTTP/1.1", upstream: "http://unix:///var/run/puma/my_app.sock:/get", host: "securities-api-prod.elasticbeanstalk.com"
2015/05/20 16:27:32 [crit] 1537#0: *20 connect() to unix:///var/run/puma/my_app.sock failed (2: No such file or directory) while connecting to upstream, client: 172.31.51.94, server: _, request: "POST /get HTTP/1.1", upstream: "http://unix:///var/run/puma/my_app.sock:/get", host: "securities-api-prod.elasticbeanstalk.com"
2015/05/20 16:28:53 [crit] 1537#0: *52 connect() to unix:///var/run/puma/my_app.sock failed (2: No such file or directory) while connecting to upstream, client: 172.31.51.94, server: _, request: "GET /datapoint?tickers=AAPL&datapoints=Ratings HTTP/1.1", upstream: "http://unix:///var/run/puma/my_app.sock:/datapoint?tickers=AAPL&datapoints=Ratings", host: "securities-api-prod.elasticbeanstalk.com"
2015/05/20 16:30:47 [crit] 1537#0: *69 connect() to unix:///var/run/puma/my_app.sock failed (2: No such file or directory) while connecting to upstream, client: 172.31.51.94, server: _, request: "POST /get HTTP/1.1", upstream: "http://unix:///var/run/puma/my_app.sock:/get", host: "securities-api-prod.elasticbeanstalk.com"

I think puma is running -

[ec2-user@ip-172-31-44-135 nginx]$ ps aux | grep puma
root     23299  1.0  0.2  53008  1428 ?        Ss   16:38   0:00 su -s /bin/bash -c puma -C /opt/elasticbeanstalk/support/conf/pumaconf.rb webapp
webapp   23314  0.0  2.4  75764 14604 ?        Rsl  16:38   0:00 /opt/rubies/ruby-2.1.4/bin/ruby /opt/rubies/ruby-2.1.4/bin/puma -C /opt/elasticbeanstalk/support/conf/pumaconf.rb
ec2-user 23317  0.0  0.1 110284   844 pts/0    S+   16:38   0:00 grep puma

pumaconf.rb

directory '/var/app/current'
threads 8, 32
workers %x(grep -c processor /proc/cpuinfo)
bind 'unix:///var/run/puma/my_app.sock'
stdout_redirect '/var/log/puma/puma.log', '/var/log/puma/puma.log', true
daemonize false

Anyone know what's going on?

回答1:

I faced the same error and adding these two lines to config/puma.rb fixed the problem:

bind "unix:///var/run/puma/my_app.sock"
pidfile "/var/run/puma/my_app.sock"

After this step I faced another error to add ENV values, which is very straight forward.

Hope this helps.

回答2:

This line in your logfile means, that you've configured your nginx incorrectly.

upstream: "http://unix:///var/run/puma/my_app.sock:/get"

Actually nginx tries to use unix domain socket as HTTP url.

Can't say exactly what is wrong at your nginx config without it, but you should have something like this:

upstream backend {
  server backend1.example.com weight=5;
  server 127.0.0.1:8080       max_fails=3 fail_timeout=30s;
  server unix:/tmp/backend3;

  server backup1.example.com  backup; 
}

You should also check out this nginx doc http://nginx.org/en/docs/http/ngx_http_upstream_module.html