How to quickly create a podman environment

This article describes how to install podman and create a podman container

environment

I will try 8

install podman

Podman is a container environment, first install Podman on the host. Execute the following command to install podman:

[root@localhost ~]# yum -y install podman

Then modify the size of the user namespace:

[root@localhost ~]# echo "user.max_user_namespaces=28633" >> /etc/sysctl.d/userns.conf
[root@localhost ~]# sysctl -p /etc/sysctl.d/userns.conf
user.max_user_namespaces = 28633

Let's create a podman container to take a look. The following is the UBI image of RHEL:

[root@localhost ~]# podman run ubi8/ubi cat /etc/os-release
Resolved "ubi8/ubi" as an alias (/etc/containers/registries.conf.d/001-rhel-shortnames.conf)
Trying to pull registry.access.redhat.com/ubi8/ubi:latest...
Getting image source signatures
Checking if image destination supports signatures
Copying blob ce3c6836540f done  
Copying blob 63f9f4c31162 done  
Copying config cc06568478 done  
Writing manifest to image destination
Storing signatures
NAME="Red Hat Enterprise Linux"
VERSION="8.5 (Ootpa)"
ID="rhel"
ID_LIKE="fedora"
VERSION_ID="8.5"
PLATFORM_ID="platform:el8"
PRETTY_NAME="Red Hat Enterprise Linux 8.5 (Ootpa)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:redhat:enterprise_linux:8::baseos"
HOME_URL="https://www.redhat.com/"
DOCUMENTATION_URL="https://access.redhat.com/documentation/red_hat_enterprise_linux/8/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"

REDHAT_BUGZILLA_PRODUCT="Red Hat Enterprise Linux 8"
REDHAT_BUGZILLA_PRODUCT_VERSION=8.5
REDHAT_SUPPORT_PRODUCT="Red Hat Enterprise Linux"
REDHAT_SUPPORT_PRODUCT_VERSION="8.5"

Create Dockerfile

A Dockerfile can now be created to specify how to build the new image. First you need to create a directory for the Dockerfile:

[root@localhost ~]# mkdir ~/myc
[root@localhost ~]# cd ~/myc

Create a file Dockerfile to build a new image:

[root@localhost myc]# vim Dockerfile

FROM ubi8/ubi:latest
RUN dnf install -y nano

Start using podman build to create the container:

[root@localhost myc]# podman build -f Dockerfile -t ubi-with-nano
[root@localhost myc]# podman build -f Dockerfile -t ubi-with-nano
STEP 1/2: FROM ubi8/ubi:latest
STEP 2/2: RUN dnf install -y nano
Updating Subscription Management repositories.
Unable to read consumer identity
...

Use podman imagesto confirm whether to create a new image:

[root@localhost myc]# podman images

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Now that you can run the container, check that the nano editor is available:

[root@localhost myc]# podman run localhost/ubi-with-nano /usr/bin/which nano
/usr/bin/nano

Check if it is installed by looking at the location of the nano executable.

Nano is now installed in your custom container. You can also run the container interactively:

[root@localhost myc]# podman run -it localhost/ubi-with-nano /bin/bash
[root@d1f0e46f2b6d /]# ls
bin   dev  home  lib64      media  opt   root sbin  sys  usr
boot  etc  lib  lost+found  mnt    proc  run srv   tmp  var
[root@d1f0e46f2b6d /]# 

Run in a container exitto exit the container.

You can use podman psto view running containers, if you need to view stopped containers, you can add -aoptions:

[root@localhost myc]# podman ps 
[root@localhost myc]# podman ps -a

storage

One thing that often confuses new users is their ephemeral nature. For example, enter the file created in the container. After exiting, enter again and find that the file is gone. Next, we mount the folder in the container that needs to store permanent files to a folder in the system. The following creates a storage location locally:

[root@localhost ~]# mkdir /pod_data

Then start the container using your storage directory as some relative mount point. This example /pod_databinds a local directory to a location named in the container /storage , which must be appended at directory location  :Zso that SELinux can switch contexts between the host and Podman.

[root@localhost ~]# podman run -it --volume /pod_data:/storage:Z localhost/ubi-with-nano
[root@d590bc344b76 /]# echo "hello podman" >> /storage/msg.txt
[root@d590bc344b76 /]# exit
exit
[root@localhost ~]# cat /pod_data/msg.txt 
hello podman

You can see that after the directory is bound, write data in the container, exit the container, and /pod_datayou can see the written content on the local machine.

Summarize

This article describes how to install podman and create a podman container