Installing docker with nginx-proxy I got docker-php-ext-install not found error

I need to install laravel 5 app on Digital Ocean Server (under kubuntu 18) using Docker with VIRTUAL_HOST pointing to my my.freenom.com host using proxy server (https://github.com/jwilder/nginx-proxy) and for this in my app I use configuraion

docker-compose.yml:

version: '3.1'

services:

    web:
        image: jwilder/nginx-proxy
        build:
            context: ./web
            dockerfile: Dockerfile.yml

        environment:
            - APACHE_RUN_USER =#1000
            - VIRTUAL_HOST    =my.freenom.com
        volumes:
            - ./mysite.template:/etc/nginx/conf.d/mysite.template

        ports:
            - 8085:80
        working_dir: ${APP_PTH_CONTAINER}


    db:
        image: mysql:5.5.62
        restart: always
        environment:
            MYSQL_ROOT_PASSWORD: 1
        volumes:
            - ${DB_PATH_HOST}:/var/lib/mysql


    adminer:
        image: adminer
        restart: always
        ports:
            - 8086:80
        links:
            - db


    composer:
        image: composer:1.6
        volumes:
            - ${APP_PATH_HOST}:${APP_PTH_CONTAINER}
        working_dir: ${APP_PTH_CONTAINER}
        command: composer install --ignore-platform-reqs

and in web/Dockerfile.yml :

FROM nginx:1.10

 RUN apt-get update -y && apt-get install -y libpng-dev  \
     nano  libmcrypt-dev 

 RUN docker-php-ext-install \
     pdo_mysql \
     mcrypt \
     && a2enmod \
     rewrite

but running command :

docker-compose up -d --build

I got error :

 docker-php-ext-install: not found

Why error and which is correct way?

Thanks!

via Chebli Mohamed