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I want to use a dockerized SQL database server, an additional client (here: phpmyadmin) and a reverse proxy to make the client interface reachable from outside servers.

So far I used this docker-compose file:

version: '3'

services:
        mariatest:
                image: mysql
                restart: always
                networks:
                       - dbnet
                environment:
                        MYSQL_ROOT_PASSWORD: password
                        MYSQL_DATABASE: test
                        MYSQL_USER: test
                        MYSQL_PASSWORD: test

        phpmatest:
                depends_on:
                        - mariatest
                image: phpmyadmin/phpmyadmin
                restart: always
                networks:
                        - dbnet
                ports:
                        - "9080:80"
                environment:
                        MYSQL_ROOT_PASSWORD: password
                        PMA_HOST: mariatest

        reverse:
                image: nginx
                networks:
                        - dbnet
                ports:
                        - "8000:80"
                volumes:
                        - /var/dockervolumes/nginx:/etc/nginx

networks:
     dbnet:

The taken from the volume I get the nginx default.conf file as

server {
    listen       80;
    server_name  localhost;

    location / {
        proxy_set_header X-Real-IP  $remote_addr;
        proxy_set_header X-Forwarded-For $remote_addr;
        proxy_set_header Host $host;
        proxy_pass http://localhost:9080/;
    }

    #error_page  404              /404.html;

    # redirect server error pages to the static page /50x.html
    #
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }
}

When using the local machine with http://localhost:9080 I can use the PMA without any problems. When trying to use the reverse proxy address (http://localhost:8000) I only get an nginx error the page I am looking for is unavailable. Inside the logs I see that the reverse proxy fails on the connect() with connection refused.

What am I missing for such setups?

2

Answers


  1. Most likely because localhost is container-based. Have you tried putting in your host’s ip address, eg:

    proxy_pass http://[HOSTIP]:9080/;
    

    You may need to either static your container IPs or request them by their hostname. To use DNS, set the container host name (one way is to set container_name), eg:

    services:
        phpmatest:
            container_name: phpmatest
    

    and in nginx conf file:

    proxy_pass http://phpmatest:80/;
    

    should work because they are on the same container network.

    You will need to also set up nginx to receive DNS from docker, in case a container needs to restart or change. There are tutorials on how to do this elsewhere.

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  2. Two issues with your code :

    First :-

    /var/dockervolumes/nginx:/etc/nginx
    This doesn’t let nginx start inside container because nginx configuration doesn’t get auto-created due to volume binding.

    Try using docker ps command to verify.

    Using /var/dockervolumes/nginx:/etc/nginx/conf.d works

    I am assuming you will place your default.conf file inside conf.d folder

    Note: If you bind any directory inside container to host system,
    that directory is not initialised by container.

    Second :-

    proxy_pass http://localhost:9080/;
    

    You assuming that localhost inside your container and you real host is same.

    Use proxy_pass http://phpmatest; that will work because your service name is phpmatest

    Note: If you create a customer docker network i.e dbtest in your case. All services using same network are directly accessible by their name i.e phpmatest in your case.

    Following works :-

    docker-compose file

    version: '3'
    
    services:
            mariatest:
                    image: mysql
                    restart: always
                    networks:
                           - dbnet
                    environment:
                            MYSQL_ROOT_PASSWORD: password
                            MYSQL_DATABASE: test
                            MYSQL_USER: test
                            MYSQL_PASSWORD: test
    
            phpmatest:
                    depends_on:
                            - mariatest
                    image: phpmyadmin/phpmyadmin
                    restart: always
                    networks:
                            - dbnet
                    ports:
                            - "9080:80"
                    environment:
                            MYSQL_ROOT_PASSWORD: password
                            PMA_HOST: mariatest
    
            reverse:
                    image: nginx
                    networks:
                            - dbnet
                    ports:
                            - "8000:80"
                    volumes:
                            - /var/dockervolumes/nginx:/etc/nginx/conf.d
    
    networks:
         dbnet:
    

    default.conf

    server {
        listen       80;
        server_name  localhost;
    
        location / {
            proxy_set_header X-Real-IP  $remote_addr;
            proxy_set_header X-Forwarded-For $remote_addr;
            proxy_set_header Host $host;
            proxy_pass http://phpmatest;
        }
    
        #error_page  404              /404.html;
    
        # redirect server error pages to the static page /50x.html
        #
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   /usr/share/nginx/html;
        }
    }
    
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