RHEL 8 New Features for Experienced Linux Administrators

Install the container software packages.

1. Log in to servera as the root user.

   [student@workstation ~]$ ssh root@servera

2. Install the container-tools module.

   [root@servera ~]# yum module install container-tools
   ...output omitted...
   Is this ok [y/N]: y
   ...output omitted...

Create a container from scratch and configure it to run bash. Label this container rhel-base.

1. Create a new container from scratch.

   [root@servera ~]# buildah from scratch
   working-container

2. Mount the root filesystem of the working-container container.

   [root@servera ~]# buildah mount working-container
   /var/lib/containers/storage/overlay/240a...b6ce/merged

3. Install the bash and the coreutils packages on the working-container container.

   [root@servera ~]# yum install \
   > --installroot /var/lib/containers/storage/overlay/240a...b6ce/merged \
   > bash coreutils \
   > --releasever 8 \
   > --setopt install_weak_deps=false
   ...output omitted...
   Is this ok [y/N]: y
   ...output omitted...

4. Clean up the yum cache on the working-container container.

   [root@servera ~]# yum clean all \
   > --installroot /var/lib/containers/storage/overlay/240a...b6ce/merged \
   > --releasever 8
   ...output omitted...
   12 files removed

5. Configure bash as the first command to run.

   [root@servera ~]# buildah config --cmd /bin/bash working-container

6. Label the working-container container rhel-base.

   [root@servera ~]# buildah config --label name=rhel-base working-container

Create a container image named rhel-base based on the working-container container.

1. Unmount the working-container container.

   [root@servera ~]# buildah unmount working-container
   e6d1...2850
   

2. Create the rhel-base container image based on the working-container container.

   [root@servera ~]# buildah commit working-container rhel-base
   ...output omitted...
   Writing manifest to image destination
   Storing signatures
   b6d8...0a6a

3. Verify that the rhel-base container image is available.

   [root@servera ~]# buildah images
   IMAGE NAME           IMAGE TAG  IMAGE ID       CREATED AT          SIZE
   localhost/rhel-base  latest     b6d88a1866eb   Feb 4, 2019 07:20   291 MB

Create a new container with the rhel-base container image.

1. Review the specifications of the rhel-base container image.

   [root@servera ~]# podman inspect localhost/rhel-base
   ...output omitted...
           "Config": {
               "Cmd": [
                   "/bin/bash"
               ],
               "Labels": {
                   "name": "rhel-base"
               }
           },
   ...output omitted...

2. Create a container using the rhel-base container image. Use the --rm option to delete the container when you exit it. When done, exit the container.

   [root@servera ~]# podman run --rm -it localhost/rhel-base /bin/bash
   bash-4.4# exit
   exit
   [root@servera ~]# 

Remove the working-container container and the rhel-base container image. When done, log off from servera.

1. Remove the working-container container.

   [root@servera ~]# buildah rm working-container
   e724...797f

2. Remove the rhel-base container image.

   [root@servera ~]# buildah rmi rhel-base
   ...output omitted...

3. Log off from servera.

   [root@servera ~]# exit
   [student@workstation ~]$