Hi tomasnorre,

I installed also an Elk Log Stack with one click install on Ubuntu 14.04.
But for me it worked fine.
Your error was that the service kibana was not running.
Maybe the droplet deployment of ELK Stack was not ready.
How I found out the error see analysis:

Problem:
2015/07/26 08:57:40 [error] 934#0: *3 connect() failed (111: Connection refused) while connecting to upstream, client: 37.24.151.202, server: , request: “GET / HTTP/1.1”, upstream: “http://127.0.0.1:5601/”, host: “46.101.233.103”

Analysis:

Nginx trying to connect to localhost:5601

root # grep -r "5601" /etc/nginx/
/etc/nginx/sites-available/kibana:        proxy_pass http://localhost:5601;

I looked into /etc/nginx/sites-available/kibana:

root # cat /etc/nginx/sites-available/kibana 
server {
    listen 80;

    # server_name kibana.myhost.org;

    auth_basic "Restricted Access";
    auth_basic_user_file /etc/nginx/conf.d/kibana.htpasswd;

    location / {
        proxy_pass http://localhost:5601;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
    }
}

Nginx using a Reverse Proxy

To reproduce your error i stopped the kibana service

root # service kibana stop

Result:
502 Bad Gateway

Solution:

#check if kibana is running
root # service kibana status
root # netstat -pant | grep 5601
tcp        0      0 127.0.0.1:5601          0.0.0.0:*               LISTEN      2227/node
root # ps -ef | grep kibana | grep -v "grep "
kibana    2227     1  0 10:04 ?        00:00:01 /opt/kibana/bin/../node/bin/node /opt/kibana/bin/../src/bin/kibana.js

#if the service is not running 
root # service kibana start 

I hope this helped you.

Best regards,
MSahl

Check your kibana.yml file.

the server.host should be the same as what in the proxy_pass

nginx config
proxy_pass http://localhost:5601;

kibana.yml
server.host: “localhost”

after restart it should fix the bad gateway issue.

I’ve been seeing this issue pop up a couple of times with the pre-installed ELK stack.
The CPU suddenly spikes and Kibana is bricked. Restarting Kibana should work but i’ve found that it doesn’t always fix it immediately.

CentOS users might need to run this command:

$ setsebool httpd_can_network_connect on -P

This is because the webserver is not allowed to make new network connections, so it can not proxy the request.