Docker image pushing but my volume not persist

This message to clear up a problem I am having with the use of docker with my php application.

Indeed, I execute locally my dockers images (nginx, phpmyadmin and php with my application) and everything works fine. However, I use a volume mounted in my container app with php which allows me to be able to modify hot files (without need to build at each edit).

However when I push this image to a repository and I pull it on another desktop, the volume containing my application is not there.

Have you ever faced this concern?

Please find my docker-compose.yml and Dockerfile :

docker-compose.yml

version: "3.7"
services:
  app:
    build:
      args:
        user: web
        uid: 1000
      context: ./
      dockerfile: Dockerfile
    image: myblog
    container_name: myblog-app
    restart: unless-stopped
    working_dir: /var/www/
    volumes:
      - ./:/var/www
    networks:
      - myblog

  db:
    image: mysql:5.7
    container_name: myblog-db
    restart: unless-stopped
    environment:
      MYSQL_DATABASE: ${DB_DATABASE}
      MYSQL_ROOT_PASSWORD: ${DB_PASSWORD}
      MYSQL_PASSWORD: ${DB_PASSWORD}
      MYSQL_USER: ${DB_USERNAME}
      SERVICE_TAGS: dev
      SERVICE_NAME: mysql
    volumes:
      - ./.docker/mysql/database.sql:/docker-entrypoint-initdb.d/init.sql
      - ./.docker/mysql/data:/var/lib/mysql
    networks:
      - myblog

  phpmyadmin:
    depends_on:
      - db
    image: phpmyadmin/phpmyadmin
    restart: always
    ports:
      - 8002:80
    environment:
      PMA_HOST: db
      MYSQL_ROOT_PASSWORD: ${DB_PASSWORD}
    networks:
      - myblog

  nginx:
    image: nginx:alpine
    container_name: myblog-nginx
    restart: unless-stopped
    ports:
      - 8000:80
    volumes:
      - ./:/var/www
      - ./.docker/nginx/conf.d:/etc/nginx/conf.d
    networks:
      - myblog

networks:
  myblog:
    driver: bridge

Dockerfile

FROM php:7.3-fpm

# Arguments defined in docker-compose.yml
ARG user
ARG uid

# Install system dependencies
RUN apt-get update && apt-get install -y 
    git 
    curl 
    libpng-dev 
    libonig-dev 
    libxml2-dev 
    libzip-dev 
    zip 
    unzip

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

# Install PHP extensions
RUN docker-php-ext-install pdo_mysql mbstring exif pcntl bcmath gd
RUN docker-php-ext-install zip
RUN docker-php-ext-enable zip

# Get latest Composer
COPY --from=composer:latest /usr/bin/composer /usr/bin/composer

# Create system user to run Composer and Artisan Commands
RUN useradd -G www-data,root -u $uid -d /home/$user $user
RUN mkdir -p /home/$user/.composer && 
    chown -R $user:$user /home/$user

# Set working directory
WORKDIR /var/www

USER $user

Thanks in advance

Answer

This is expected behavior, because the data inside Volumes are not part of an image. Volumes are used to persist data generated in containers or to pass dynamic data into containers via bind-mounts e.g. configs, credentials or certificates.

https://docs.docker.com/storage/volumes/

Your docker-compose.yml and its services using volumes mounting your local directory via - .:/path/to/dir are only good for local development, because you may see changes of your application instant and without having to rebuild images.

If you want to see your code inside the images on another machine you need to use COPY in your Dockerfile, rebuild the image and push every time you change your code !

You will also need to change your docker-compose.yml by adding volumes.

https://docs.docker.com/compose/compose-file/#volumes