Connect Nginx container with a custom PHP-FPM container

Question

I have created two custom images, one for Nginx, the other for Php-fpm based on alpine, created their containers, but for some reason Nginx gives me 502 Bad Gateway when trying to serve a php file, and the following error :

/var/log/nginx/error.log :

2024/04/16 15:28:29 [error] 25#25: *16 connect() failed (111: Connection refused) while connecting to upstream, client: 172.30.0.1, server: , request: "GET / HTTP/1.1", upstream: "fastcgi://172.30.0.3:9000", host: "localhost:8000"

but when I work with php:fpm-alpine an image from Docker Hub, it works perfectly, you will find below a docker compose that contains both the Docker Hub image, and my custom image, then replace in the Nginx default.conf file fastcgi_pass my-php-fpm:9000; to fastcgi_pass php-fpm:9000; in order to test both of them.

don't forget to run nginx -s reload or restart the nginx container after modifying the config file.

I don't know from where is the problem, all of the containers share the same volume and the same network.

Nginx Dockerfile :

FROM alpine:3.19

RUN apk upgrade && apk update
RUN apk add nginx && apk add openssl

RUN mkdir /var/www/html

COPY ./default.conf /etc/nginx/http.d/

CMD nginx -g "daemon off;"

EXPOSE 80

default.conf :

server {
    listen 80;

    root /var/www/html;

    index index.php index.html;

    location ~ \.php$ {
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass php-fpm:9000;
        fastcgi_index index.php;
        include fastcgi_params;

        try_files $uri =404;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_path_info;
    }

}

my-php-Fpm Dockerfile :

FROM alpine:3.19

RUN apk upgrade && apk update
RUN apk add curl php83 php83-phar php83-fpm
RUN mkdir -p /var/www/html/

CMD php-fpm83 -F

EXPOSE 9000

docker-compose.yml :

version: "3.8"

services:
  nginx:
    image: my-nginx
    build:
      context: ./nginx/
    container_name: nginx
    ports:
      - 8000:80
    networks:
      - net
    volumes:
      - ./index.php:/var/www/html/index.php

  php-fpm:
    image: php:fpm-alpine
    container_name: php-fpm
    ports:
      - 9000
    networks:
      - net
    volumes:
      - ./index.php:/var/www/html/index.php

  my-php-fpm:
    image: my-php-fpm
    build:
      context: ./my-php-fpm/
    container_name: my-php-fpm
    ports:
      - 9000
    networks:
      - net
    volumes:
      - ./index.php:/var/www/html/index.php

networks:
  net:

index.php :

<?php echo phpinfo();?>

Directory Structure:

test
├── docker-compose.yml
├── index.php
├── my-php-fpm
│   └── Dockerfile
└── nginx
    ├── Dockerfile
    └── default.conf

Answer 1

Thanks to this StackOverflow answer that I found, I could get my custom php-fpm container to work as expected

since I am using php-fpm82 I found its config within this path /etc/php82/php-fpm.d/www.conf I had to search for

listen = 127.0.0.1:9000

and change it to

listen = 0.0.0.0:9000

restarted the container and the php page index.php got displayed as it should, but the thing that I don't understand is why the DockerHub image php:fpm-alpine works well with my Nginx container, even with listen = 127.0.0.1:9000 set in its configuration.

ANY IDEAS?

Thanks for @β.εηοιτ.βε and his clarification, you can find more informations within the comment section;