Why `file_get_contents` don't work in Docker? How can I solve this issue?

I need to embed svg from php. And for this I used

<?= file_get_contents( get_template_directory_uri() . "/images/scroll_to_explore.svg" ) ?>

When I served project locally, all were fine. But now project migrated to Docker. And I got next errors everywhere I have same code:

Warning: file_get_contents(http://0.0.0.0:8000/wp-content/themes/my_theme/images/scroll.svg): 
Failed to open stream: Connection refused in /var/www/html/wp-content/themes/my_theme/parts/front/cover.php

This is my docker-compose.yml:

version: '3.3'

services:
  db:
    image: mysql:latest
    volumes:
      - ./database.sql:/docker-entrypoint-initdb.d/init.sql # prepopulate database
      - db_data:/var/lib/mysql # persist database data inside docker storage
    restart: always
    env_file:
      - .env
    environment:
      DOCKER_COMPOSE_YML_LOCATION: ${PWD}
    container_name: wp_db
  phpmyadmin:
    image: phpmyadmin/phpmyadmin
    restart: always
    ports:
      - "8080:80"
    volumes:
      - /sessions
    environment:
      PMA_HOST: db
      MYSQL_ROOT_PASSWORD: ${MYSQL_ROOT_PASSWORD}
      DOCKER_COMPOSE_YML_LOCATION: ${PWD}
      UPLOAD_LIMIT: 300M
    container_name: wp_phpmyadmin
    depends_on:
      - db
  wordpress:
    depends_on:
      - db
    image: wordpress:latest
    ports:
      - "8000:80"
    restart: always
    environment:
      # debug mode
      WORDPRESS_DEBUG: 1

      # docker wp config settings
      WORDPRESS_DB_HOST: db:3306
      WORDPRESS_DB_USER: ${MYSQL_USER}
      WORDPRESS_DB_PASSWORD: ${MYSQL_PASSWORD}
      WORDPRESS_DB_NAME: ${MYSQL_DATABASE}
      DOCKER_COMPOSE_YML_LOCATION: ${PWD}
    volumes:
      # Theme, plugins and uploads
      - ./wp-content:/var/www/html/wp-content
      # Configurations
      - .htaccess:/var/www/html/.htaccess
      # PHP Configuration
      - ./php-extra.ini:/usr/local/etc/php/conf.d/php-extra.ini
    container_name: wp_wordpress
volumes:
  db_data: {}

This is my php-extra.ini:

allow_url_fopen: 1

I tried to add custom php configuration to php-extra.ini but it didn't help

Check your configuration. You really shouldn't try to connect via 0.0.0.0... it's a special address for configuring the server to listen on any interface.

If this file you need is on disk, there's no need to load via HTTP anyway. If you do need to load it over HTTP, consider 127.0.0.1 or localhost instead.