Podman : Use by common users2022/03/14

	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

62791

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

[root@dlp ~]#

cat /etc/subuid

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

cat /etc/subgid

cent: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

cent:100000:65536
centos:165536:65536
redhat:231072:65536
cent:100000:65536
centos:165536:65536
redhat:231072:65536

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

[centos@dlp ~]$

podman pull centos:stream9

[centos@dlp ~]$

podman images

REPOSITORY             TAG         IMAGE ID      CREATED     SIZE
quay.io/centos/centos  stream9     44ffcc4acee8  3 days ago  152 MB

[centos@dlp ~]$

podman run centos:stream9 echo "run rootless containers"

run rootless containers

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

[centos@dlp ~]$

ll ~/.local/share/containers/storage

total 8
-rw-r--r--. 1 centos centos   3 Mar 14 12:52 defaultNetworkBackend
drwx------. 2 centos centos  27 Mar 14 12:52 libpod
drwx------. 2 centos centos   6 Mar 14 12:52 mounts
drwx------. 5 centos centos 185 Mar 14 12:53 overlay
drwx------. 3 centos centos 124 Mar 14 12:53 overlay-containers
drwx------. 3 centos centos 116 Mar 14 12:52 overlay-images
drwx------. 2 centos centos 129 Mar 14 12:53 overlay-layers
-rw-r--r--. 1 centos centos  64 Mar 14 12:53 storage.lock
drwx------. 2 centos centos   6 Mar 14 12:52 tmp
-rw-r--r--. 1 centos centos   0 Mar 14 12:52 userns.lock

# possible to create Pods

[centos@dlp ~]$

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

[centos@dlp ~]$

podman pod ls

POD ID        NAME        STATUS      CREATED        INFRA ID      # OF CONTAINERS
a31c8a738d9b  test-pod    Created     3 seconds ago  b21c47fc9c00  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

[centos@dlp ~]$

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

[centos@dlp ~]$

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

[centos@dlp ~]$

podman ps

CONTAINER ID  IMAGE                          COMMAND               CREATED        STATUS            PORTS                 NAMES
96a4f51834c0  srv.world/centos-nginx:latest  /usr/sbin/nginx -...  4 seconds ago  Up 5 seconds ago  0.0.0.0:1024->80/tcp  gallant_pascal

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