/var/www/boot_end.shbefore starting your image. If either of these files exist, they will be executed in the beginning or at the end of the dockware entrypoint script.
docker-compose.ymlto use build instead of an image and point to a local directory that we will create next.
customin the same directory and place a file
Dockerfilein it. This is a plain Dockerfile and can do everything usual Dockerfiles can do.