Persistent storage - how?

Hi,

I have followed the documentation, and now I have started a mongodb container as follows:

docker run --rm -d --network ahem-mongo -p 27017:27017 \
--mount type=volume,source=mongodb.data,target=/data \
--env-file /root/.env.mongodb --name mongodb mongo

My mongodb container with persistent storage seems to run fine:

root@d1379ea48a72:/# df -h
Filesystem      Size  Used Avail Use% Mounted on
overlay          30G  9.0G   21G  30% /
tmpfs            64M     0   64M   0% /dev
tmpfs           1.7G     0  1.7G   0% /sys/fs/cgroup
shm              64M     0   64M   0% /dev/shm
/dev/sda2        30G  9.0G   21G  30% /data

When I stop the container, the volume is still alive:

]# docker volume ls
DRIVER              VOLUME NAME
[...]
local               mongodb.data

But when I start the container, all databases that were created previously are gone.

So the documentation seems to be wrong somehow, I think.

Is there a better way to save the data with a scp cron job or something similar?