Podman : Use by common users2021/11/11

	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

63797

# 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      1b52edb08181  7 days ago  159 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  54 Nov 11 10:55 libpod
drwx------. 2 fedora fedora   6 Nov 11 10:55 mounts
drwx------. 5 fedora fedora 185 Nov 11 10:56 overlay
drwx------. 3 fedora fedora 124 Nov 11 10:56 overlay-containers
drwx------. 3 fedora fedora 116 Nov 11 10:55 overlay-images
drwx------. 2 fedora fedora 129 Nov 11 10:56 overlay-layers
-rw-r--r--. 1 fedora fedora  64 Nov 11 10:56 storage.lock
drwx------. 2 fedora fedora   6 Nov 11 10:55 tmp
-rw-r--r--. 1 fedora fedora   0 Nov 11 10:55 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
8018c74975fd  test-pod    Created     3 seconds ago  4d1bee0c531d  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
760da425aaf9  docker.io/library/nginx:latest  nginx -g daemon o...  4 seconds ago  Up 5 seconds ago  0.0.0.0:1024->80/tcp  sleepy_merkle

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