i am trying to make my website (which is from a docker container, inside a google cloud platform vm) and the first page work just fine.

but when i try to access any other page than the home one, for exemple: http://34.130.236.145:25556/metainfo/1

it says

    requests.exceptions.ConnectionError: HTTPConnectionPool(host=34.130.236.145, 
    port=25555): Max retries exceeded with url: /metainfo/1 (Caused by 
    NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7cee6c119100>: 
    Failed to establish a new connection: [Errno 111] Connection refused'))

this is my code for the domain:

       @app.route('/metainfo/<file_number>')
       def getMetaPageInfo(file_number): #pragma: no cover
       response = requests.get('http://' + BACK_END_IP + ':' + BACK_END_PORT + '/metainfo/' 
       + file_number)
        data = None
        if response.status_code == 200:
                data = json.loads(response.content.decode('utf-8'))
        else:
                data = {'message': 'Impossible de contacter l'api'}

        return page_template('Méta-Information', data)

and the code that calls the two variables you see:

    app = Flask('memoryanalysisfe')
    TEMPLATE_FOLDER = app.root_path + '/project/app/templates/'
    BACK_END_IP = 'backend'
    BACK_END_PORT = '25555'

For more clarifications, BACK_END_IP = ‘34.130.236.145’ is set like this because if i put anything else it give me:

    requests.exceptions.ConnectionError: HTTPConnectionPool(host='backend', port=25555): 
    Max retries exceeded with url: /bitmap/1 (Caused by NameResolutionError(" 
    <urllib3.connection.HTTPConnection object at 0x7f6c74909f10>: Failed to resolve 
    'backend' ([Errno -2] Name or service not known)"))

also, my docker file for my front end is

    FROM demers/python420w4a
    COPY ./requirements.txt /
    RUN pip3 install -r /requirements.txt
    RUN apt-get update -y
    RUN apt-get install -y xxd
    WORKDIR /var/lib
    CMD ["./run.sh", "./project/app/memoryfront.py", "25556"]

and this is for my backend:

    FROM demers/python420w4a
    COPY ./requirements.txt /
    RUN pip3 install -r /requirements.txt
    RUN apt-get update -y
    RUN apt-get install -y xxd
    WORKDIR /var/lib
    CMD ["./run.sh", "./project/main/memoryapi.py", "25555"]

and this is my ./startDocker.sh script:

    #!/bin/bash
    sudo aa-remove-unknown
    SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
    vol_name=memory_ad_vol
    api_cont_name=memoryapi_ad_cnt
    api_image_name=memoryapi_ad_img
    website_cont_name=memorywebsite_ad_cnt
    website_image_name=memorywebsite_ad_img
    echo "Début du lancement de l'api et du Site Web dans Docker"
    echo "Le nom pour l'image de l'api: $api_image_name"
    echo "Le nom pour l'image du Site Web: $website_image_name"
    echo "Le nom du volume où vont ce trouver les images et conteneurs: $vol_name"
    echo "Le nom pour le conteneur de l'api: $api_cont_name"
    echo "Le nom pour le conteneur du Site Web: $website_cont_name"
    ###CLEANUP
    echo "Stoping everything"
    docker-compose -f "$SCRIPT_DIR/docker-compose.yml" down
    ###REBUILD
    echo "Creating everything"
    docker-compose -f "$SCRIPT_DIR/docker-compose.yml" up -d

and lastly, my docker-compose.yml file:

    version: '3.8'
    services:
      memory_Backend:
        build:
          context: ./
          dockerfile: ./project/docker/dockerfilebackend
        image: memoryapi_ad_img
        volumes:
          - ./:/var/lib
        ports:
          - 25555:25555
      memory_Frontend:
        build:
          context: ./
          dockerfile: ./project/docker/dockerfilefrontend
        image: memorywebsite_ad_img
        volumes:
          - ./:/var/lib
        ports:
          - 25556:25556

Thanks in advance for helping me!