Docker Rootless Ubuntu don't work

[asferreir]

I've been testing Kasm and came across an issue with the Docker Rootless images for Ubuntu, in both available versions. The Docker doesn't start properly, and when checking the log, it shows the following error:

filter is not configured

• [ -w /docker ]
• [ -d /home/kasm-user ]
• rootlesskit=
• command -v docker-rootlesskit
• command -v rootlesskit
• rootlesskit=rootlesskit
• break
• [ -z rootlesskit ]
• : /docker/dockerd-rootless
• :
• :
• : builtin
• : auto
• : auto
• net=
• mtu=
• [ -z ]
• command -v slirp4netns
• grep -qw -- --netns-type
• slirp4netns --help
• net=slirp4netns
• [ -z ]
• mtu=65520
• [ -z slirp4netns ]
• [ -z 65520 ]
• dockerd=dockerd
• [ -z ]
• _DOCKERD_ROOTLESS_CHILD=1
• export _DOCKERD_ROOTLESS_CHILD
• id -u
• [ 1000 = 0 ]
• command -v selinuxenabled
• exec rootlesskit --state-dir=/docker/dockerd-rootless --net=slirp4netns --mtu=65520 --slirp4netns-sandbox=auto --slirp4netns-seccomp=auto --disable-host-loopback --port-driver=builtin --copy-up=/etc --copy-up=/run --propagation=rslave /usr/local/lib/docker/dockerd-rootless.sh
  time="2024-03-25T23:48:09-03:00" level=warning msg="[rootlesskit:parent] The host root filesystem is mounted as "master:764". Setting child propagation to "rslave" is not supported."
  [rootlesskit:parent] error: failed to setup UID/GID map: newuidmap 1424 [0 1000 1 1 100000 65536] failed: newuidmap: write to uid_map failed: Operation not permitted
  : exit status 1