Tuesday, December 4, 2018

RHEL 8 Beta: Bits & Pieces

Yes, Red Hat has recently released the Beta version of Red Hat Enterprise Linux (RHEL) 8.  This is still in a rigorous testing and development phase, so there could be some changes compared with ‘Stable’ release later. As everyone I was also keen on installing the ‘beta’ version and checking how it works, what are the differences, what’s new, what is not available etc., hence, I thought of writing up this post to give a glimpse of RHEL 8 beta.

In this post, I’m not going to run through the installation process, rather, I’d be interested in pointing out new changes, what’s-in & what’s-not, and some interesting aspects of RHEL 8. 

(:) New Kernel Version 4.18

RHEL8 is based on Fedora 28 upstream version and it is kernel is 4.18 version.  The release version is code named Ootpa.

(:) Repo Channels ( BaseOS & AppStream )

There are two repository channels available which are “BaseOS” & “AppStream” (application stream) for content management. The “BaseOS” repo provide core functionality, however, “AppStream” is for extended functionality beyond the “BaseOS”.  Both of these repo channels are required and available with RHEL subscriptions, and once subscription is activated it gets enabled as shown below:

If there is any trouble in getting the subscription activated, then follow the steps as shown in the below snap, which should help:

NOTE: Thanks to one of my friends Christian who has helped me with this. He had mentioned about this issue in one of the discussion threads @Red Hat (https://access.redhat.com/discussions/3694451) which points to a Bugzilla thread being opened to address this.

(:) Software Management by DNF

The 'yum' command is just a symbolic link to 'dnf' as package management is done by dnf which provides much improved performance and well designed approach to overall package management.  Yum is based on DNF technology and yum command provides backward compatibility with YUM v3 being used in earlier versions.

The ‘rpm’ is of version 4.14 which is an improved edition compared to earlier 4.11 version. One of the noticeable enhancements in this version is the capability of validating entire package using best hash algorithms in a separate step prior to installation. Now, packages being built on RHEL8 uses SHA256 hash (earlier MD5 was being used) on the compressed payload.

(:) Python 3.6 is the default implementation

The python version 3.6 is the default implementation available in RHEL 8. The earlier version ‘python 2.7’ is also available which can be installed using the command ‘yum install python2’.

(:) Wayland - default display server

The default display server is ‘Wayland’ used by Gnome Display Manager in RHEL8. The Xorg server was being used in earlier version. Xorg is still available as an optional choice which could be selected if required.

The "gnome shell" is of version 3.28 now. The KDE (KDE Plasma Workspaces) display manager being used as an alternative to GNOME in RHEL 7 has been removed. Also, Red Hat doesn’t support migration from RHEL 7 KDE to RHEL 8 GNOME.

(:) nftables - default network packet filtering

The "nftables" is the default network packet filtering which has replaced earlier "iptables" framework.  The firewalld daemon would uses nftables in the back-end. This would replace the earlier used ‘iptables’, ‘ip6tables’, ‘arptables’ & ‘ebtables’ tools. The ‘nftables’ does provide a single frame work for both IPv4 & IPv6 protocols.

(:) Chrony - default & only NTP

Chrony is the default & only NTP available in this release of RHEL 8. In earlier version (RHEL7), there were two implementation of NTP available which were 'ntp' & 'chrony'. In RHEL 8 the 'ntp' has been removed.

(:) Cockpit is now available by default

Cockpit is now installed by default and available. This gets installed automatically on non-minimal mode and required ports gets enabled in firewall.

The "Cockpit" provides an enhanced framework which can be used to access/edit/change many system settings. This provides access over a web interface which can be launched using http://<hostname>:9090 url. It also provides a terminal which can be used to execute commands and connects using ssh in the back-end.

Also, virtual machines (libvirt based) can be easily managed using Cockpit now. The "virt-manager" which was being used earlier has been deprecated and it is replaced by "cockpit".

To access Cockpit dashboard, make sure the “cockpit.socket” is enabled and running and port 9090 (TCP) is allowed in firewall as shown in the below snap:

Once done, Cockpit service could be accessed using a web browser and an initial login screen would comes up as shown below:

After successful login using user credential, we could get to see a nice screen with many options for administration, and user could do many a things here.  It also provides a terminal to execute commands which is a nice feature.

(:) New kernel supports 5-level paging

In earlier version there was 4-level paging implementation which could address 48/46 bit of virtual/physical addresses, and there was an upper physical bus limit to 64TB. With the upcoming Intel processors, these limits have been extended to 57/52 bit of virtual/physical memory addressing with 128 PiB of virtual address space and 4 PB of physical memory capacity.

(:) Database servers in RHEL 8

The following database servers are available with new RHEL version:

- MySQL 8.0
- MariaDB 10.3
- PostgreSQL 10 and PostgreSQL 9.6
- Redis 4.0

(:) Change in NFS configuration file

The earlier used NFS configuration file which is "/etc/sysconfig/nfs" has been replaced by "/etc/nfs.conf" file. Red Hat Enterprise Linux 8 attempts to automatically convert all options from "/etc/sysconfig/nfs" to "/etc/nfs.conf" when upgrading from RHEL7. Also, the service daemons were also changed as "nfs.service" has become 'nfs-server.service' in RHEL 8.

(:) Installation sources

RHEL 8 Beta version can be installed using ISO image which is available in two formats:
- Binary DVD
- Netinstall DVD (boot.iso)
The "binary DVD" provides complete installation image including packages as well, however, the "Netinstall DVD" provide minimal image to boot up and needs access to remote/network access for further installation. The binary DVD is a bit heavy compared to earlier version which is of size 6.5GB.

Anyone who wants to try installing and do some testing, could visit this page of Red Hat fore more details:


(:) The network scripts are deprecated

The network scripts are not available by default in RHEL 8. There is a new version of 'ifup' & 'ifdown' being used which would need the NetworkManager daemon to be running and uses "nmlci" in the back-end.  If earlier network scripts needed then one has to install 'network-scripts' package.

Also, there is no ‘network.service’ which used to serve as legacy daemon in earlier version. All network related commands or utilities would utilize the NetworkManager service in the back-end and without which it would not work.

(:) The "Btrfs" file system has been removed

In RHEL 8 the ‘Btrfs’ file system is not supported. In earlier RHEL 7 version it was on technology preview. Users could no longer create or mount ‘Btrfs’ file systems in Red Hat Enterprise Linux 8.

(:) podman in container technology

The ‘podman’ tool is fully supported feature in RHEL 8. The podman tool manages pods, container images, and containers on a single node. A set of container images are available, however, RHSCL, DTS, and DotNet container images are not provided in RHEL 8 Beta.

The all new RHEL 8 beta release is integrated with many new functions and features. It is cloud and container friendly platform which provides stable, secure environment for deployment of hybrid cloud workloads.

I've listed some of the noticeable changes, features, enhancements only here. If someone wants to know a complete list of all new features/functions added or removed then one has to refer to the Release Guide of RHEL 8 Beta. All the best!


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