ECS Fargateで503 Service Temporarily Unavailableになる

server {
    listen 80;
    root /var/www/html/public;
    index index.php;
    charset utf-8;
    error_log /var/log/nginx/error_test.log;

    location / {
        root /var/www/html/public;
        try_files $uri $uri/ /index.php$is_args$args;
    }

    location ~ \.php$ {
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass 127.0.0.1:9000;
        fastcgi_index index.php;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_path_info;
    }
}

FROM nginx:1.20-alpine
COPY ./docker/nginx/default.conf /etc/nginx/conf.d/default.conf
COPY ./src /var/www/html
ENV TZ=Asia/Tokyo
EXPOSE 80

FROM php:8.1-fpm-bullseye

WORKDIR /var/www/html

COPY ./src /var/www/html
COPY ./docker/php/php.ini /usr/local/etc/php/php.ini
##省略

zend.exception_ignore_args = off
expose_php = on
max_execution_time = 30
max_input_vars = 1000
upload_max_filesize = 64M
post_max_size = 128M
memory_limit = 256M
error_reporting = E_ALL
display_errors = on
display_startup_errors = on
log_errors = on
error_log = /dev/stderr
default_charset = UTF-8

[Date]
date.timezone = Asia/Tokyo

[mysqlnd]
mysqlnd.collect_memory_statistics = on

[Assertion]
zend.assertions = 1

[mbstring]
mbstring.language = Japanese