Podman : Use by common users2024/05/05

	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

63680

# 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:~#

useradd noble

root@dlp:~#

useradd numbat

root@dlp:~#

cat /etc/subgid /etc/subgid

ubuntu:100000:65536
noble:165536:65536
numbat:231072:65536
ubuntu:100000:65536
noble:165536:65536
numbat: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      bf3dc08bfed0  5 days ago  78.7 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 160
drwx------ 8 ubuntu ubuntu   4096 May  5 06:14 ./
drwx------ 4 ubuntu ubuntu   4096 May  5 06:12 ../
-rw-r--r-- 1 ubuntu ubuntu 122880 May  5 06:14 db.sql
-rw-r--r-- 1 ubuntu ubuntu      8 May  5 06:12 defaultNetworkBackend
drwx------ 2 ubuntu ubuntu   4096 May  5 06:12 libpod/
drwx------ 2 ubuntu ubuntu   4096 May  5 06:12 networks/
drwx------ 5 ubuntu ubuntu   4096 May  5 06:14 overlay/
drwx------ 3 ubuntu ubuntu   4096 May  5 06:14 overlay-containers/
drwx------ 3 ubuntu ubuntu   4096 May  5 06:12 overlay-images/
drwx------ 2 ubuntu ubuntu   4096 May  5 06:14 overlay-layers/
-rw-r--r-- 1 ubuntu ubuntu     64 May  5 06:14 storage.lock
-rw-r--r-- 1 ubuntu ubuntu      0 May  5 06:12 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
4a02b0965cab  test-pod    Created     4 seconds ago  871d3cd55578  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 -itd -p 1023:80 ubuntu /bin/bash

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 -itd -p 1024:80 ubuntu /bin/bash

ubuntu@dlp:~$

podman ps

CONTAINER ID  IMAGE                            COMMAND     CREATED       STATUS        PORTS                 NAMES
8e83a302f0f5  docker.io/library/ubuntu:latest  /bin/bash   1 second ago  Up 2 seconds  0.0.0.0:1024->80/tcp  mystifying_maxwell

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