Run Laravel app in Docker container, but autoload.php file does not exist

I have a problem with the execution of my laravel app in docker, my containers are launched successfully but when I try to access to my app I got this error :

Warning: require(/var/www/public/../vendor/autoload.php): failed to open stream: No such file or directory in /var/www/public/index.php on line 24

Fatal error: require(): Failed opening required '/var/www/public/../vendor/autoload.php' (include_path='.:/usr/local/lib/php') in /var/www/public/index.php on line 24

I don't know why because I run the composer install on the Dockerfile so I think that autoload file exists?

Please find my Dockerfile:

FROM php:7.2-fpm

# Copy composer.lock and composer.json
COPY composer.lock composer.json /var/www/

# Set working directory
WORKDIR /var/www

# Install dependencies
RUN apt-get update && apt-get install -y \
    build-essential \
    mariadb-client \
    libpng-dev \
    libjpeg62-turbo-dev \
    libfreetype6-dev \
    locales \
    zip \
    jpegoptim optipng pngquant gifsicle \
    vim \
    unzip \
    libzip-dev \
    git \
    curl

# Clear cache
RUN apt-get clean && rm -rf /var/lib/apt/lists/*

# Install extensions
RUN docker-php-ext-install mysqli pdo pdo_mysql tokenizer pcntl
RUN docker-php-ext-install gd zip

# Install composer
RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer

# Add user for laravel application
RUN groupadd -g 1000 www
RUN useradd -u 1000 -ms /bin/bash -g www www

# Copy existing application directory contents
COPY . /var/www

# Run composer install
RUN composer install
RUN composer dump-autoload

# Copy existing application directory permissions
COPY --chown=www:www . /var/www

# Change current user to www
USER www

# Expose port 9000 and start php-fpm server
EXPOSE 9000
CMD ["php-fpm"]

My docker-compose.yml :

version: '3'
services:

  #PHP Service
  app:
    build:
      context: .
      dockerfile: Dockerfile
    image: digitalocean.com/php
    container_name: bumapp
    restart: unless-stopped
    volumes:
       - ./:/var/www
       - ./docker/php/local.ini:/usr/local/etc/php/conf.d/local.ini
    tty: true
    environment:
      SERVICE_NAME: app
      SERVICE_TAGS: dev
    working_dir: /var/www
    networks:
      - app-network

  #Nginx Service
  webserver:
    image: nginx:alpine
    container_name: webserver
    restart: unless-stopped
    volumes:
      - ./:/var/www
      - ./docker/nginx/conf.d/:/etc/nginx/conf.d/
    tty: true
    ports:
      - "80:80"
      - "443:443"
    networks:
      - app-network

  #MySQL Service
  db:
    image: mysql:5.7.22
    container_name: db
    restart: unless-stopped
    volumes:
      - dbdata:/var/lib/mysql
      - ./docker/mysql/my.cnf:/etc/mysql/my.cnf
    tty: true
    ports:
      - "3306:3306"
    environment:
      MYSQL_DATABASE: mustache
      MYSQL_ROOT_PASSWORD: 888*
      SERVICE_TAGS: dev
      SERVICE_NAME: mysql
    networks:
      - app-network
volumes:
  dbdata:
    driver: local
#Docker Networks
networks:
  app-network:
    driver: bridge

The nginx/app.conf :

server {
    listen 80;
    index index.php index.html;
    error_log  /var/log/nginx/error.log;
    access_log /var/log/nginx/access.log;
    root /var/www/public;
    location ~ \.php$ {
        try_files $uri =404;
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass app:9000;
        fastcgi_index index.php;
        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;
        gzip_static on;
    }
}

Maybe do you already had this problem?

Thanks