RHCA - EX180

Red Hat Certified Specialist in Containers and Kubernetes

Podman host setup

dnf module install container-tools

dnf install -y buildah

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 images

podman images

Inspect images. *Useful for locating config.user

podman inspect registry.access.redhat.com/rhscl/mariadb-102-rhel7:latest

Configure container volume path

sudo mkdir /srv/mariadb
sudo chown -R 27:27 /srv/mariadb # UID found in podman inspect
sudo semanage fcontext -m -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

Basic pod status and names

podman ps

Enter container in interactive shell

podman exec -it container-name /bin/bash

Commit changes to running image

podman commit container-name image-name

Export image

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

Remove images

podman rmi image-name --force

Restore/Load image

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

Dockerfile Basics

Container for scanning a network.

# Start with a base image
FROM registry.access.redhat.com/ubi8
# Maintainer information
MAINTAINER ClusterApps <mail@clusterapps.com>

# Run commands to build the container
# Do as much with the fewest RUN lines
RUN yum --assumeyes update && \
yum --assumeyes install \
nmap iproute procps-ng && \
bash && \
yum clean all

# Entrypoint is the command that run when the ccontainer starts
ENTRYPOINT ["/usr/bin/nmap"]
#  The arguments for the entrypoint
CMD ["-sn", "192.168.252.0/24"]

Build the image with a tag

podman build -t notes180 .

List images

podman images

Run the image

podman run localhost/notes180