"Recv failure: Connection Reset By Peer" during requests between PHP Symfony containers

Question

Background

I am setting up a local development environment that somewhat replicates a production server environment using NginX, MySQL, and Symfony/PHP-based web applications.

Codebase

I have set up a small public repository to replicate the issue, consisting of three containers: NginX, App, and API.

https://gitlab.com/Extarion/docker-workshop

Intended Functionality

The API container has a single path /api/data that returns a message containing the current date and time.

The App container performs a request to the API app via Symfony's HttpClient, retrieving said message and showing it on a simple web page.

Primary Issue

Once the App container executes these lines of code, it returns a 500 error.

$response = $this->client->request('GET', 'http://API:9000/api/data');

$message = $response->getContent();

HTTP 500 Internal Server Error

Symfony\Component\HttpClient\Exception\TransportException

Recv failure: Connection reset by peer for "http://api:9000/api/data".

I am in the process of learning more about Docker, NginX, and the related configuration for my applications. What am I missing?

Troubleshooting So Far

I've attempted some suggestions found online, but I can't properly troubleshoot this problem not knowing what it relates to exactly.

• Requesting data from http://api.local/api/data directly works as expected.
• Both requests to api.local:9000 and API:9000 resolve to the same 500 error.
• Tried changing 127.0.0.1:9000 to 0.0.0.0:9000 in /usr/local/etc/php-fpm.d/www.conf`.
• Tried exposing the PHP ports via docker-compose.yml by adding expose for port 9000 for both API and App containers.
• No entries are added to api-access.log and api-error.log.

Docker Configuration

version: '3'

services:
    server:
        container_name: NginX
        image: nginx:1.14.0
        tty: true
        ports:
            - '80:80'
        networks:
            - local-network
        volumes:
            - .\nginx:/etc/nginx/conf.d
            - .\api:/var/www/api
            - .\app:/var/www/app

    api:
        container_name: API
        image: php:8.1.3-fpm
        tty: true
        networks:
            - local-network
        volumes:
            - .\api:/var/www/api

    app:
        container_name: App
        image: php:8.1.3-fpm
        tty: true
        networks:
            - local-network
        volumes:
            - .\app:/var/www/app

networks:
    local-network:
        driver: bridge

NginX Configuration

API

server {
    server_name api.local;

    index index.php;
    root /var/www/api/public;

    access_log /var/log/nginx/api-access.log;
    error_log /var/log/nginx/api-error.log;

    location ~ \.php$ {
        fastcgi_split_path_info ^(.+\.php)(/.+)$;

        fastcgi_pass API:9000;
        fastcgi_index index.php;

        fastcgi_buffers 16 16k;
        fastcgi_buffer_size 32k;

        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_path_info;
    }

    location / {
            try_files $uri $uri/ /index.php?$query_string;
    }
}

App

server {
    server_name app.local;

    index index.php;
    root /var/www/app/public;

    access_log /var/log/nginx/app-access.log;
    error_log /var/log/nginx/app-error.log;

    location ~ \.php$ {
        fastcgi_split_path_info ^(.+\.php)(/.+)$;

        fastcgi_pass App:9000;
        fastcgi_index index.php;

        fastcgi_buffers 16 16k;
        fastcgi_buffer_size 32k;

        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_path_info;
    }

    location / {
            try_files $uri $uri/ /index.php?$query_string;
    }
}

PHP Setup

API Route

class DataController extends AbstractController
{
    /**
     * @Route("/api/data")
     */
    public function index(): Response
    {
        $today = new DateTime();

        return $this->json('The date and time are currently ' . $today->format('Y-m-d H:i:s'));
    }
}

App Route

class ExternalDataController extends AbstractController
{
    private HttpClientInterface $client;

    public function __construct(HttpClientInterface $client)
    {
        $this->client = $client;
    }

    /**
     * @Route("/")
     */
    public function index(): Response
    {
        // $response = $this->client->request('GET', 'http://API/api/data'); // Failed to connect to api port 80: Connection refused for "http://api/api/data".
        $response = $this->client->request('GET', 'http://API:9000/api/data'); // Recv failure: Connection reset by peer for "http://api:9000/api/data".

        $message = $response->getContent();

        return $this->render('external_data/index.html.twig', [
            'message' => $message,
        ]);
    }
}