Podman : Use by common users2021/07/29

	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

63178

# sub UID/GID mapping file

# 100000 to 165535 (100000 + 65536 - 1) UID are used for running processes in containers on [rocky] user

[root@dlp ~]#

cat /etc/subuid

rocky:100000:65536
[root@dlp ~]#

cat /etc/subgid

rocky: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 centos

[root@dlp ~]#

useradd redhat

[root@dlp ~]#

cat /etc/subgid /etc/subgid

rocky:100000:65536
centos:165536:65536
redhat:231072:65536
rocky:100000:65536
centos:165536:65536
redhat:231072:65536

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

[rocky@dlp ~]$

podman pull docker.io/rockylinux/rockylinux

[rocky@dlp ~]$

podman images

REPOSITORY                       TAG     IMAGE ID      CREATED      SIZE
docker.io/rockylinux/rockylinux  latest  333da17614b6  5 weeks ago  234 MB

[rockyos@dlp ~]$

podman run rockylinux echo "run rootless containers"

run rootless containers

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

[rockyos@dlp ~]$

ll ~/.local/share/containers/storage

total 4
drwx------. 2 rocky rocky  39 Jul 29 16:36 cache
drwx------. 2 rocky rocky  27 Jul 29 16:36 libpod
drwx------. 2 rocky rocky   6 Jul 29 16:36 mounts
drwx------. 5 rocky rocky 159 Jul 29 16:36 overlay
drwx------. 3 rocky rocky 124 Jul 29 16:36 overlay-containers
drwx------. 3 rocky rocky 116 Jul 29 16:36 overlay-images
drwx------. 2 rocky rocky 129 Jul 29 16:36 overlay-layers
-rw-r--r--. 1 rocky rocky  64 Jul 29 16:36 storage.lock
drwx------. 2 rocky rocky   6 Jul 29 16:36 tmp
-rw-r--r--. 1 rocky rocky   0 Jul 29 16:36 userns.lock

# possible to create Pods

[rocky@dlp ~]$

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

[rocky@dlp ~]$

podman pod ls

POD ID        NAME      STATUS   CREATED        INFRA ID      # OF CONTAINERS
a45fa9ec18bb  test-pod  Created  5 seconds ago  6738b8478bbd  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

[rocky@dlp ~]$

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

[rocky@dlp ~]$

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

[rocky@dlp ~]$

podman ps

CONTAINER ID  IMAGE                  COMMAND               CREATED        STATUS            PORTS                 NAMES
e35c94ecffcf  srv.world/rocky-nginx  /usr/sbin/nginx -...  5 seconds ago  Up 5 seconds ago  0.0.0.0:1024->80/tcp  wonderful_chebyshev

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