Podman : Use by common users2022/04/28

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

# default name spaces number

root@dlp:~#

cat /proc/sys/user/max_user_namespaces

63572

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

root@dlp:~#

cat /etc/subuid

ubuntu:100000:65536
root@dlp:~#

cat /etc/subgid

ubuntu: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 jammy

root@dlp:~#

adduser jellyfish

root@dlp:~#

cat /etc/subgid /etc/subgid

ubuntu:100000:65536
jammy:165536:65536
jellyfish:231072:65536
ubuntu:100000:65536
jammy:165536:65536
jellyfish:231072:65536

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

ubuntu@dlp:~$

podman pull ubuntu

ubuntu@dlp:~$

podman images

REPOSITORY                TAG         IMAGE ID      CREATED     SIZE
docker.io/library/ubuntu  latest      3f4714ee068a  6 days ago  80.3 MB

ubuntu@dlp:~$

podman run ubuntu echo "run rootless containers"

run rootless containers

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

ubuntu@dlp:~$

ll ~/.local/share/containers/storage

total 40
drwx------ 9 ubuntu ubuntu 4096 Apr 28 07:15 ./
drwx------ 4 ubuntu ubuntu 4096 Apr 28 07:16 ../
drwx------ 2 ubuntu ubuntu 4096 Apr 28 07:15 libpod/
drwx------ 2 ubuntu ubuntu 4096 Apr 28 07:15 mounts/
drwx------ 5 ubuntu ubuntu 4096 Apr 28 07:16 overlay/
drwx------ 3 ubuntu ubuntu 4096 Apr 28 07:16 overlay-containers/
drwx------ 3 ubuntu ubuntu 4096 Apr 28 07:16 overlay-images/
drwx------ 2 ubuntu ubuntu 4096 Apr 28 07:16 overlay-layers/
-rw-r--r-- 1 ubuntu ubuntu   64 Apr 28 07:16 storage.lock
drwx------ 2 ubuntu ubuntu 4096 Apr 28 07:15 tmp/
-rw-r--r-- 1 ubuntu ubuntu    0 Apr 28 07:15 userns.lock

# possible to create Pods

ubuntu@dlp:~$

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

ubuntu@dlp:~$

podman pod ls

POD ID        NAME        STATUS      CREATED        INFRA ID      # OF CONTAINERS
477f00ef3630  test-pod    Created     2 seconds ago  a09898b74a92  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

ubuntu@dlp:~$

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

ubuntu@dlp:~$

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

ubuntu@dlp:~$

podman ps

CONTAINER ID  IMAGE                          COMMAND               CREATED        STATUS            PORTS                 NAMES
1c960231dfed  srv.world/ubuntu-nginx:latest  /usr/sbin/nginx -...  6 seconds ago  Up 6 seconds ago  0.0.0.0:1024->80/tcp  priceless_engelbart

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