Podman : Use by common users2021/05/14

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

# default name spaces number

[root@dlp ~]#

cat /proc/sys/user/max_user_namespaces

63856

# sub UID/GID mapping file

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

[root@dlp ~]#

cat /etc/subuid

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

cat /etc/subgid

fedora: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 redhat

[root@dlp ~]#

useradd centos

[root@dlp ~]#

cat /etc/subgid /etc/subgid

fedora:100000:65536
redhat:165536:65536
centos:231072:65536
fedora:100000:65536
redhat:165536:65536
centos:231072:65536

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

[fedora@dlp ~]$

podman pull fedora

[fedora@dlp ~]$

podman images

REPOSITORY                         TAG     IMAGE ID      CREATED      SIZE
registry.fedoraproject.org/fedora  latest  5f05951e2065  2 weeks ago  187 MB

[fedora@dlp ~]$

podman run fedora echo "run rootless containers"

run rootless containers

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

[fedora@dlp ~]$

ll ~/.local/share/containers/storage

total 4
drwx------. 2 fedora fedora  39 May 13 04:22 cache
drwx------. 2 fedora fedora  27 May 13 04:22 libpod
drwx------. 2 fedora fedora   6 May 13 04:22 mounts
drwx------. 5 fedora fedora 185 May 13 04:22 overlay
drwx------. 3 fedora fedora 124 May 13 04:22 overlay-containers
drwx------. 3 fedora fedora 116 May 13 04:22 overlay-images
drwx------. 2 fedora fedora 129 May 13 04:22 overlay-layers
-rw-r--r--. 1 fedora fedora  64 May 13 04:22 storage.lock
drwx------. 2 fedora fedora   6 May 13 04:22 tmp
-rw-r--r--. 1 fedora fedora   0 May 13 04:22 userns.lock

# possible to create Pods

[fedora@dlp ~]$

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

[fedora@dlp ~]$

podman pod ls

POD ID        NAME      STATUS   CREATED        INFRA ID      # OF CONTAINERS
96ab76ff5db0  test-pod  Created  7 seconds ago  46047e94eb7d  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

[fedora@dlp ~]$

podman run -d -p 1023:80 docker.io/library/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

[fedora@dlp ~]$

podman run -d -p 1024:80 docker.io/library/nginx

[fedora@dlp ~]$

podman ps

CONTAINER ID  IMAGE                           COMMAND               CREATED        STATUS            PORTS                 NAMES
379c82eeb226  docker.io/library/nginx:latest  nginx -g daemon o...  7 seconds ago  Up 8 seconds ago  0.0.0.0:1024->80/tcp  clever_benz

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