Podman : Use by common users2021/08/28

	It's possible to use Podman containers by common users.
[1]	By default, sub UID/GID that are used on user name spaces are asigned to run containers.

# default name spaces number

root@dlp:~#

cat /proc/sys/user/max_user_namespaces

63892

# sub UID/GID mapping file
# 100000 to 165535 (100000 + 65536 - 1) UID are used for running processes in containers on [debian] user

root@dlp:~#

cat /etc/subuid

debian:100000:65536
root@dlp:~#

cat /etc/subgid

debian:100000:65536

# when added new users, sub UID/GID are also added
# n=0, n++
# [start UID/GID = 100000 + (65536 * n)]
# [end UID/GID = (start UID/GID) + 65536 - 1]

root@dlp:~#

adduser bullseye

root@dlp:~#

adduser buster

root@dlp:~#

cat /etc/subgid /etc/subgid

debian:100000:65536
bullseye:165536:65536
buster:231072:65536
debian:100000:65536
bullseye:165536:65536
buster:231072:65536

# on Debian 11 default, Cgroupv2 is enabled,

# so, run follows to allow to use [podman] for each common user

root@dlp:~#

loginctl enable-linger 1000

[2]	It's possible to run [podman] by common users.

debian@dlp:~$

podman pull debian

debian@dlp:~$

podman images

REPOSITORY                TAG     IMAGE ID      CREATED      SIZE
docker.io/library/debian  latest  fe3c5de03486  11 days ago  129 MB

debian@dlp:~$

podman run debian echo "run rootless containers"

run rootless containers

# containers related files are located under the [$HOME/.local] directory

debian@dlp:~$

ll ~/.local/share/containers/storage

total 36
drwx------ 2 debian debian 4096 Aug 28 03:10 cache
drwx------ 2 debian debian 4096 Aug 28 03:09 libpod
drwx------ 2 debian debian 4096 Aug 28 03:09 mounts
drwx------ 5 debian debian 4096 Aug 28 03:26 overlay
drwx------ 3 debian debian 4096 Aug 28 03:26 overlay-containers
drwx------ 3 debian debian 4096 Aug 28 03:10 overlay-images
drwx------ 2 debian debian 4096 Aug 28 03:26 overlay-layers
-rw-r--r-- 1 debian debian   64 Aug 28 03:26 storage.lock
drwx------ 2 debian debian 4096 Aug 28 03:09 tmp
-rw-r--r-- 1 debian debian    0 Aug 28 03:09 userns.lock

# possible to create Pods

debian@dlp:~$

podman pod create -p 8081:80 -n test-pod

debian@dlp:~$

podman pod ls

POD ID        NAME      STATUS   CREATED        INFRA ID      # OF CONTAINERS
3f5056cf53dd  test-pod  Created  6 seconds ago  fe2d25ff6f4e  1

# for port mapping,
# it's impossible to use less than [1024] ports on Host machine by common users
# possible to use over [1024] ports

debian@dlp:~$

podman run -d -p 1023:80 srv.world/debian-nginx

Error: rootlessport cannot expose privileged port 1023, you can add 'net.ipv4.ip_unprivileged_port_start=1023' to /etc/sysctl.conf (currently 1024), or choose a larger port number (>= 1024): listen tcp 0.0.0.0:1023: bind: permission denied

debian@dlp:~$

podman run -d -p 1024:80 srv.world/debian-nginx

debian@dlp:~$

podman ps

CONTAINER ID  IMAGE                   COMMAND               CREATED        STATUS            PORTS                 NAMES
78b807f96e29  srv.world/debian-nginx  /usr/sbin/nginx -...  7 seconds ago  Up 7 seconds ago  0.0.0.0:1024->80/tcp  admiring_poincare

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