Docker: FTP/SFTP to /var/www/ in Docker Container?

I'm trying to run Docker on my VPS, to maximise the use of my server.

My server mainly run LAMP stack, but I wanted to have other Docker-image based apps too.

So, I did make a Docker Container with LAMP running. The question is, how do I manage to upload files into the container (which Apache's /var/www/ is there.)?

SFTP is what I've been always using, but I can't find the way to SSH into the Docker Container, so I can access filesystem in the container, so I'd prefer that.

But if there are better practice, I'm willing to adapt it!

Use docker volumes, to store files in host system. For example, you can run your image with these options:

docker run --name mylamp -v /docker/site:/var/www -p 80:80 me/mylamp:tag

Now, your mylamp image mounts internal /var/www directory to external /docker/site directory, so you can use SSH/SFTP/FTP to upload files to /docker/site directory on your host system, and it will be visible inside docker image in /var/www directory.