How to self-start the php-fpm service when building a LNMP environment with docker?

in order to facilitate development, we plan to create a LNMP environment based on docker, which makes it much more convenient to change computers or unify the team"s development environment.

choreographed a docker-compose.yaml file with nginx, php-fpm, mysql, redis and other services. All of them have been done except php-fpm

tell me about the process:

first of all, pull"s official php image php:7.x-fpm . Create images and containers, and have no problems connecting to other containers
but the PHP extension (extension) supported by this image is too few, and many commonly used ones do not (such as the gd library)
is installed by setting RUN docker-php-ext-install gd in Dockerfile, indicating that libpng library
enter the container and install it with yum install-y libpng , prompting yum is an unknown command
installs yum through rpm xxx , prompting that rpm is an unknown command.

then change the way of thinking and plan to create your own php-fpm image based on the centos image, so:

pull official centos 7.x image, enter the container to download the php source code package, and compile and install it smoothly
start the container and find that the php-fpm service
in docker-compose , command and entrypoint define commands (not at the same time):
/ path/to/sbin/php-fpm-y / path/to/etc/php-fpm.conf . When the container starts, the service fails to start, and the prompt message is equivalent to entering: php-fpm-h , all related parameters

I feel that this problem is because php-fpm is in the sbin directory and can only be run by a superuser, but executing command or entrypoint when the container is started is not a superuser, so it fails
, which causes me to enter php container to manually open the service every time I start container orchestration

I really don"t know what to do. I hope all of you can give me some hints:
1. How do I make the centos container automatically open the php-fpm service when it starts?
2. Or instead of using this idea, we can use other solutions

Thank you very much, thank you ~