RHEL 8 New Features for Experienced Linux Administrators

Log in to servera as the root user.

[student@workstation ~]$ ssh root@servera

Install the container-tools module, if not already installed.

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

Use buildah to create a new container from scratch.

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

List the available containers.

[root@servera ~]# buildah containers
CONTAINER ID  BUILDER  IMAGE ID     IMAGE NAME     CONTAINER NAME
bc4c2a71c4c9     *                  scratch        working-container

Label the newly created container custom-container.

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

Inspect the container.

[root@servera ~]# buildah inspect working-container
...output omitted...
    "Container": "working-container",
    "ContainerID": "bc4c2a71c4c9fbb11b7b88127a67173b82d0e4f95e7935c4a36b8d3010b8de16",
    "MountPoint": "",
    "ProcessLabel": "",
    "MountLabel": "",
    "ImageAnnotations": null,
    "ImageCreatedBy": "",
    "OCIv1": {
        "created": "2019-02-07T05:24:20.845648888Z",
        "architecture": "amd64",
        "os": "linux",
        "config": {
            "Labels": {
                "name": "custom-container"
...output omitted...

Mount the root file system of working-container.

[root@servera ~]# buildah mount working-container
/var/lib/containers/storage/overlay/14e1...fbed/merged

Initialize the RPM database within the container.

[root@servera ~]# rpm --root \
> /var/lib/containers/storage/overlay/14e1...fbed/merged \
> --initdb

Download the redhat-release-server RPM on servera.

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

[root@servera ~]# yumdownloader --destdir=/tmp redhat-release-server
...output omitted...
redhat-release-8.0-0.44.el8.x86_64.rpm             3.4 MB/s |  45 kB   00:00

Install the redhat-release-server RPM on working-container.

[root@servera ~]# rpm -ivh \
> --root /var/lib/containers/storage/overlay/14e1...fbed/merged \
> /tmp/redhat-release*.rpm 
...output omitted...
Updating / installing...
   1:redhat-release-8.0-0.44.el8      ################################# [100%]

Copy the local repository file to the working-container mount point.

[root@servera ~]# cp \
> /etc/yum.repos.d/rhel_dvd.repo \
> /var/lib/containers/storage/overlay/14e1...fbed/merged/etc/yum.repos.d/

Install the httpd package in the container.

[root@servera ~]# yum install \
> --installroot /var/lib/containers/storage/overlay/14e1...fbed/merged \
> httpd
...output omitted...
Is this ok [y/N]: y
...output omitted...
Complete!

Create some text content and expose it as an index.html on working-container mount directory.

[root@servera ~]# echo "custom-container Working OK" > \
> /var/lib/containers/storage/overlay/14e1...fbed/merged/var/www/html/index.html

Configure /usr/sbin/httpd as the first command to run in working-container.

[root@servera ~]# buildah config --cmd "/usr/sbin/httpd -DFOREGROUND" \
> working-container

Configure the internal listening port for httpd daemon in working-container.

[root@servera ~]# buildah config --port 80/tcp working-container

Clean up the Yum cache on the working-container container.

[root@servera ~]# yum clean all \
> --installroot /var/lib/containers/storage/overlay/14e1...fbed/merged \
...output omitted...

Unmount the root file system of working-container.

[root@servera ~]# buildah unmount working-container
14e1392a5a7d06da689e26c1438b9092008f9c012affbae943ee25720ecbfbed

Create the container image custom-image based on the working-container container.

[root@servera ~]# buildah commit working-container custom-image
Getting image source signatures
Copying blob sha256:02f83791177ef46b84dfbf49d491971a9a83f793af08a507c1a744f842366010
 144.82 MiB / 144.82 MiB [==================================================] 9s
Copying config sha256:09901c90da2a4ea033e8083316983605e09dd34860729f1047f2d78ecea06558
 332 B / 332 B [============================================================] 0s
Writing manifest to image destination
Storing signatures
09901c90da2a4ea033e8083316983605e09dd34860729f1047f2d78ecea06558

List the available images on servera.

[root@servera ~]# buildah images
IMAGE NAME              IMAGE TAG  IMAGE ID      CREATED AT         SIZE
localhost/custom-image  latest     09901c90da2a  Feb 6, 2019 22:22  483 MB

Run a container based on the localhost/custom-image image.

[root@servera ~]# podman run -d -p 80:80 --name lab-container localhost/custom-image
1aedf5420e73b71105b02bc7fdbea406b3313ec29bde7fa3f661c1ccf4fc1a7a

Test the container httpd daemon.

[root@servera ~]# curl localhost
custom-container Working OK

Use firewalld to open the HTTP service port on servera.

[root@servera ~]# firewall-cmd --add-service=http
success

Open a new terminal and log in to serverb as the student user.

[student@workstation ~]$ ssh student@serverb

Test the container httpd daemon inside servera.

[student@serverb ~]$ curl http://servera
custom-container Working OK

Log off from serverb.

[student@serverb ~]$ exit
[student@workstation ~]$ 

Switch to the servera terminal, and stop the running container.

[root@servera ~]# podman stop lab-container
1aedf5420e73b71105b02bc7fdbea406b3313ec29bde7fa3f661c1ccf4fc1a7a

Delete the container on servera.

[root@servera ~]# podman rm lab-container
1aedf5420e73b71105b02bc7fdbea406b3313ec29bde7fa3f661c1ccf4fc1a7a

Delete the container image on servera.

[root@servera ~]# podman rmi localhost/custom-image
a8fe25c677f2878d73ace848d7fd2f2bf06f1470c94e33fee9a444eecd8e49d9

Delete the working-container container on servera.

[root@servera ~]# buildah delete working-container
bc4c2a71c4c9fbb11b7b88127a67173b82d0e4f95e7935c4a36b8d3010b8de16

Log off from servera.

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