[Unit]
Description=My Nginx Server
Requires=docker.service
After=docker.service

[Service]
ExecStartPre=-/usr/bin/docker kill mynginx
ExecStartPre=-/usr/bin/docker rm -f mynginx
ExecStartPre=/usr/bin/docker pull nginx:latest
ExecStart=/usr/bin/docker run --rm --name mynginx -p 80:80 nginx:latest