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nkhcode
Asked: 2020-11-12 20:00:31 +0800 CST

nginx proxy_pass return 502 Bad Gateway

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I'm building nginx for reverse_proxy with Spring and Docker

Here is my configuration.

nginx.conf

user  proxy;
worker_processes  auto;
error_log  logs/error.log;
error_log  logs/error.log  notice;
error_log  logs/error.log  info;
pid        logs/nginx.pid;

events {
    worker_connections  1024;
}

http {
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
    '$status $body_bytes_sent "$http_referer" '
    '"$http_user_agent" "$http_x_forwarded_for"';
    access_log  logs/access.log  main;
    sendfile            on;
    tcp_nopush          on;
    tcp_nodelay         on;
    keepalive_timeout   65;
    types_hash_max_size 2048;

    include       mime.types;
    default_type  application/octet-stream;

    include /home/wertkey/nginx/conf/conf.d/*.conf;

    client_max_body_size 200M;
    client_header_buffer_size  48k;

    server {
        listen       7070 default_server;
        listen       [::]:7070 default_server;
        server_name  _;
        root         /usr/share/nginx/html;

        location / {
        }

        error_page 404 /404.html;
        location = /404.html {
        }

        error_page 500 502 503 504 /50x.html;
        location = /50x.html {
        }
    }
}

conf.d/default.conf

server {
    listen 7070;
    server_name something.com;

    proxy_connect_timeout   900s;
    proxy_send_timeout      900s;
    proxy_read_timeout      900s;
    send_timeout            900s;

    location ^~ /editor/ {
        proxy_pass http://localhost:8081;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Host $host;

        rewrite ^/editor/(/.*)$ $1 break;
    }
}

docker

CONTAINER ID        IMAGE        COMMAND                  CREATED             STATUS              PORTS                    NAMES
a6a6a98a25a9        editor       "/bin/sh -c /usr/l..."   8 minutes ago       Up 8 minutes        0.0.0.0:8081->8080/tcp   editor

My spring server is running at 7070 port. I want to be this way.

  1. request something.com:7070/api
  2. nginx proxy_pass to 8081
  3. and docker 8081 -> 8080

But response always return 502 Bad Gateway

What am i missing?

+ I am currently running two nginxs on the same server. One is running at 8080 port and the other is running at 7070 port. 8080 nginx is for web servers and 7070 nginx is for proxy purposes. The log does not appear in 7070 nginx and the log appears in 8080 nginx. I don't know why the request goes to 8080 nginx. How can I send the request to 7070 nginx?

nginx reverse-proxy docker springframework

2 Answers

  1. When a process inside docker tries to connect to localhost:8081 that translates to "port 8081 on the docker container", and NOT "port 8081 on the host".

    For your setup, I'd encourage you to try docker-compose. With docker-compose, each container is accessible for other containers by its name (e.g.: if your containers are named backend and nginx, the latter can access the former via backend:8081).

    This is especially handy if you're using these during development, since docker-compose let you quickly start all the containers and manage them through a single interface.

    Another alternative is to change the network type on the containers.

    • 0

  2. The issue could be related to the rewrite directive in the location block. What that's doing is essentially a redirect on the client side. A possible solution would be to use the regex in the location itself rather than the rewrite:

        location ^~ /editor/(.*)$ {
        proxy_pass http://localhost:8081/$1;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Host $host;
    }
    • 0