Fedora 37
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Podman : Use by common users
2022/11/22
 
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

31599
# 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      885d2b38b819  11 days ago  190 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 8
-rw-r--r--. 1 fedora fedora   8 Nov 22 15:58 defaultNetworkBackend
drwx------. 2 fedora fedora  27 Nov 22 15:58 libpod
drwx------. 2 fedora fedora   6 Nov 22 15:58 mounts
drwx------. 2 fedora fedora  27 Nov 22 15:58 networks
drwx------. 5 fedora fedora 185 Nov 22 16:01 overlay
drwx------. 3 fedora fedora 124 Nov 22 16:01 overlay-containers
drwx------. 3 fedora fedora 116 Nov 22 15:59 overlay-images
drwx------. 2 fedora fedora 129 Nov 22 16:01 overlay-layers
-rw-r--r--. 1 fedora fedora  64 Nov 22 16:01 storage.lock
drwx------. 2 fedora fedora   6 Nov 22 15:58 tmp
-rw-r--r--. 1 fedora fedora   0 Nov 22 15:58 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
cd2851e07818  test-pod    Created     4 seconds ago  62e445d5022b  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
a74ec8e312d5  docker.io/library/nginx:latest  nginx -g daemon o...  5 seconds ago  Up 5 seconds ago  0.0.0.0:1024->80/tcp  gifted_agnesi
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