Podman

Basics

Registry file: /etc/containers/registries.conf

podman login registry.access.redhat.com

Search for images

podman search mariadb

Inspect images without downloading

skopeo inspect docker://registry.access.redhat.com/rhscl/mariadb-102-rhel7

Download images

podman pull registry.access.redhat.com/rhscl/mariadb-102-rhel7

List local images

podman images

Start a container based on an image ID. Get the ID from docker images.

podman run --name apache bitnami/apache

control-c will stop the container for all of the run commands.

Start an image based on a tag detached

podman run -d --name apache bitnami/apache:2.4.52

Start the an app with port forwarding

podman run -it -p 8080:8080 bitnami/apache

Get running images

podman ps

Get all images

podman ps -all

Enter container in interactive shell

podman exec -it container-name /bin/bash

Commit changes to running image

podman commit container-name image-name

Check container logs

podman logs <Container Name> 
podman logs -f <Container Name> # Follow the logs
podman logs --tail=25 <Container Name> # Last n lines

Stop a running image. The container ID will be in the podman ps output.

podman kill <Container ID>

Remove an image. The container ID will be in the podman ps output.

podman rm <Container ID>

Remove all images.

podman rmi --all --force

Export image

podman save image-name > /path/to/image.tar

Restore/Load image

podman load -i /path/to/image.tar

Parameters and Volumes

Create a container mount point

sudo mkdir /srv/mariadb
sudo chown -R 27:27 /srv/mariadb # UID found in podman inspect
sudo semanage fcontext -a -t container_file_t "/srv/mariadb(/.*)"
sudo restorecon -Rv /srv/mariadb

Run image
-d detached
-e per variable
-p local_port:container_port
-v local/path:/path/in/pod

podman run -d -e MYSQL_USER=user \
-e MYSQL_PASSWORD=pass -e MYSQL_DATABASE=db \
-p 33306:3306 rhscl/mariadb-102-rhel7 \
-v /srv/mariadb:/var/lib/mysql:Z # :Z isn't needed if SELinux manually configured

Pods

Create a pod for rootless containers with a specific name and map ports needed. This example creates a Wordpress pod with a dedicated MySQL database using the Bitnami Wordpress image and a MySQL image from Red Hat.

Create a storage area.

sudo mkdir /srv/pods/wordpress/database
sudo mkdir /srv/pods/wordpress/sitedata
sudo chown -R poduser:poduser /srv/pods/wordpress # Host user running the pod
sudo semanage fcontext -a -t container_file_t "/srv/pods/wordpress(/.*)"
sudo restorecon -Rv /srv/pods/wordpress

Create the pod with port maps for 8443.

podman pod create --name press -p 8443:8443

Deploy the MySQL container

podman run -d --pod press --name mysql \
-e MYSQL_ROOT_PASSWORD=ThereIsAWordHere \
-e MYSQL_USER=wordpress \
-e MYSQL_PASSWORD=presswords \
-e MYSQL_DATABASE=wordpress \
-v /machines/pods/wordpress/database:/var/lib/mysql:Z \
mysql-80-rhel7

Deploy the wordpress container.

podman run -d --name words --pod press \
-e WORDPRESS_DATABASE_HOST=press \
-e WORDPRESS_DATABASE_USER=wordpress \
-e WORDPRESS_DATABASE_NAME=wordpress \
-e WORDPRESS_DATABASE_USER=wordpress \
-e WORDPRESS_DATABASE_PORT_NUMBER=3306 \
-e WORDPRESS_DATABASE_PASSWORD=presswords \
-v /machines/pods/wordpress/site:/bitnami/wordpress:Z \
bitnami/wordpress

Systemd

Create system .service files.

To create systemd files for the above Wordpress pod:

podman generate systemd --files --name press

Creates: container-mysql.service container-words.service pod-press.service

Copy the generated file to the user's systemd directory and reload the deamons.

 cp * ~/.config/systemd/user/
 systemctl --user daemon-reload

Enable the service at boot time

systemctl --user enable pod-press.service