Nginx Docker Container: 502 Bad Gateway Response

Question

I've a service listening to 8080 port. This one is not a container.

Then, I've created a nginx container using official image:

docker run --name nginx -d -v /root/nginx/conf:/etc/nginx/conf.d -p 443:443 -p 80:80 nginx

After all:

# netstat -tupln | grep 443
tcp6       0      0 :::443                  :::*                    LISTEN      3482/docker-proxy
# netstat -tupln | grep 80
tcp6       0      0 :::80                   :::*                    LISTEN      3489/docker-proxy
tcp6       0      0 :::8080                 :::*                    LISTEN      1009/java

Nginx configuration is:

upstream eighty {
    server 127.0.0.1:8080;
}

server {
    listen 80;
    server_name eighty.domain.com;

    location / {
      proxy_pass                        
    }
}

I've checked I'm able to connect with with this server with # curl

 <html><head><meta http-equiv='refresh'
 content='1;url=/login?from=%2F'/><script>window.location.replace('/login?from=%2F');</script></head><body
 style='background-color:white; color:white;'>
 ...

It seems running well, however, when I'm trying to access using my browser, nginx tells bt a 502 bad gateway response.

I'm figuring out it can be a problem related with the visibility between a open by a non-containerized process and a container. Can I container stablish connection to a port open by other non-container process?

EDIT

Logs where upstream { server 127.0.0.1:8080; }:

2016/07/13 09:06:53 [error] 5#5: *1 connect() failed (111: Connection refused) while connecting to upstream, client: 62.57.217.25, server: eighty.domain.com, request: "GET / HTTP/1.1", upstream: "", host: "eighty.domain.com"
62.57.217.25 - - [13/Jul/2016:09:06:53 +0000] "GET / HTTP/1.1" 502 173 "-" "Mozilla/5.0 (Windows NT 10.0; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0" "-"

Logs where upstream { server 0.0.0.0:8080; }:

62.57.217.25 - - [13/Jul/2016:09:00:30 +0000] "GET / HTTP/1.1" 502 173 "-" "Mozilla/5.0 (Windows NT 10.0; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0" "-" 2016/07/13 09:00:30 [error] 5#5: *1 connect() failed (111: Connection refused) while connecting to upstream, client:
62.57.217.25, server: eighty.domain.com, request: "GET / HTTP/1.1", upstream: "", host: "eighty.domain.com" 2016/07/13 09:00:32 [error] 5#5: *3 connect() failed (111: Connection refused) while connecting to upstream, client: 62.57.217.25, server: eighty.domain.com, request: "GET / HTTP/1.1", upstream: "", host: "eighty.domain.com"
62.57.217.25 - - [13/Jul/2016:09:00:32 +0000] "GET / HTTP/1.1" 502 173 "-" "Mozilla/5.0 (Windows NT 10.0; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0" "-"

Any ideas?

Accepted Answer

Must Read

The Problem

Localhost is a bit tricky when it comes to containers. Within a docker container, localhost points to the container itself. This means, with an upstream like this:

upstream foo{
  server 127.0.0.1:8080;
}

or

upstream foo{
  server 0.0.0.0:8080;
}

you are telling nginx to pass your request to the local host. But in the context of a docker-container, localhost (and the corresponding ip addresses) are pointing to the container itself:

by addressing 127.0.0.1 you will never reach your host machine, if your container is not on the host network.

Nginx Docker Container: 502 Bad Gateway Response

7 Answers

Must Read

The Problem

Sophia Al-Mansoor