Change to pm = static on php-fpm docker image

actually, when you mount a directory to the inside of the docker-image (like something you did ./php/pool.d:/usr/local/etc/php-fpm.d)

version: '3.6'services:  wordpress:    ...    volumes:      - ./php/pool.d:/usr/local/etc/php-fpm.d    ...

you replaced it. thus, you have no configuration of the pool except a little part of it that is something like this

pm = staticpm.max_children = 10

therefore, you get the errors. to solve this trouble I can propose two ways:

• you can pass a complete pool configuration file to the inside of the docker-image and change anything you want in the new config file then change the docker-compose file from this

version: '3.6'services:  wordpress:    ...    volumes:      - ./php/pool.d:/usr/local/etc/php-fpm.d    ...

to this

version: '3.6'services:  wordpress:    ...    volumes:      - ./php/pool.d/www.conf:/usr/local/etc/php-fpm.d/www.conf    ...

• you can overwrite a part of the pool configuration by passing your new config value as a second config file to the pool directory to the inside of the docker-image. but, you must care about the file name. for example, usually, the default pool configuration file's name is www.conf so, to overwrite its configs, you must create a file with name www2.conf to load after the www.conf file (for more information see this issue: https://serverfault.com/a/806530/529531). also, your docker-compose file will be something like this

version: '3.6'services:  wordpress:    ...    volumes:      - ./php/pool.d/www2.conf:/usr/local/etc/php-fpm.d/www2.conf    ...