Let's presuppose you don't have even a MySQL DB ready.
docker run --name func-mysql \
-e MYSQL_DATABASE=funcs -e MYSQL_USER=func -e MYSQL_PASSWORD=funcpass -e MYSQL_RANDOM_ROOT_PASSWORD=yes -d mysql
For more configuration options, see docker mysql docs.
docker run --rm --privileged --link "func-mysql:mysql" \
-e "FN_DB_URL=mysql://func:funcpass@tcp(mysql:3306)/funcs" \
-it -p 8080:8080 fnproject/fnserver