To pull the docker image you can do it with:

docker pull amritgc/alpine-nginx-php5

After pulling the image from docker registry, go into project directory Then run the following commands to run php or composer:

docker run -v $(pwd):/var/www -p 80:80 amritgc/alpine-nginx-php5

You can use it as a base image like below:

FROM amritgc/alpine-nginx-php5