api-platform: Error 502 on some api routes "upstream sent too big header while reading response header from upstream"

@purplefish32

This worked for me (api/docker/nginx/conf.d/default.conf) :

server {
    root /srv/api/public;

    location / {
        # try to serve file directly, fallback to index.php
        try_files $uri /index.php$is_args$args;
    }

    location ~ ^/index\.php(/|$) {
        # Comment the next line and uncomment the next to enable dynamic resolution (incompatible with Kubernetes)
        fastcgi_pass php:9000;
        #resolver 127.0.0.11;
        #set $upstream_host php;
        #fastcgi_pass $upstream_host:9000;

        fastcgi_buffer_size          128k;
        fastcgi_buffers              4 256k;

        fastcgi_split_path_info ^(.+\.php)(/.*)$;
        include fastcgi_params;
        # When you are using symlinks to link the document root to the
        # current version of your application, you should pass the real
        # application path instead of the path to the symlink to PHP
        # FPM.
        # Otherwise, PHP's OPcache may not properly detect changes to
        # your PHP files (see https://github.com/zendtech/ZendOptimizerPlus/issues/126
        # for more information).
        fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;
        fastcgi_param DOCUMENT_ROOT $realpath_root;
        # Prevents URIs that include the front controller. This will 404:
        # http://domain.tld/index.php/some-path
        # Remove the internal directive to allow URIs like this
        internal;
    }

    # return 404 for all other php files not matching the front controller
    # this prevents access to other php files you don't want to be accessible.
    location ~ \.php$ {
      return 404;
    }
}

fastcgi_busy_buffers_size does not exists for fastcgi

By the way, thank you all for your help !

What you’re looking for is fastcgi_buffer_size and friends.

This guide seems helpful: https://gist.github.com/magnetikonline/11312172

<?php

namespace App\EventListener;

use Symfony\Component\HttpKernel\Event\ResponseEvent;

class OverrideCacheTagsListener
{
    /**
     * Makes sure that the Cache-Tags header doesn't grow infinitely in larger projects
     */
    public function onKernelResponse(ResponseEvent $event): void
    {
        $request = $event->getRequest();
        $response = $event->getResponse();

        if (
            !$request->isMethodCacheable()
            || !$response->isCacheable()
        ) {
            return;
        }

        if ($response->headers->has('Cache-Tags') && strlen($response->headers->get('Cache-Tags')) > 32) {
            $response->headers->set('Cache-Tags', md5($response->headers->get('Cache-Tags')));
        }
    }
}

services:
    App\EventListener\OverrideCacheTagsListener:
        tags:
            - { name: kernel.event_listener, event: kernel.response, priority: -3 }

@janklan I can kiss you!! Thank you very much!

I am coming here from a strange Heroku issue: fetching 59 items from api platform works, but fetching 60 items I get a strange CORS error in the browser:

... blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource ...

Looking in the Heroku PHP logs I only find

Premature end of script headers: index.php and

Error parsing script headers

On Heroku there is no way to increase the Header Size. Thus, the headers have to be limited programatically.

Please Note: I had to update the first parameter of the onKernelResponse with a ResponseEvent

I was having this problem but only on the https version of the api (port :8443). To fix it I had to increase the buffer size of the h2-proxy (editing the file ./h2-proxy/conf.d/default.conf). Like this:

# api
server {
    listen 8443 ssl http2;
    listen [::]:8443 ssl http2;

    ssl_certificate /etc/nginx/ssl/cert.crt;
    ssl_certificate_key /etc/nginx/ssl/cert.key;

    location / {
        proxy_buffer_size 256k;       # added this line
        proxy_buffers 4 256k;         # added this line
        proxy_busy_buffers_size 256k; # added this line
        proxy_pass http://api;
        proxy_http_version 1.1;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Host $host;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Forwarded-Port 8443;
    }
}

Indeed we should change the default value, and add a section here: https://api-platform.com/docs/extra/troubleshooting/#troubleshooting

I think we could probably ship with a better default out of the box. 😄