Chapter 1. Overview

Security

IPsec VPN provided by Libreswan now supports TCP encapsulation and security labels for IKEv2.

The scap-security-guide packages have been rebased to version 0.1.54, and OpenSCAP has been rebased to version 1.3.4. These updates provide substantial improvements, including:

The fapolicyd framework now provides integrity checking, and the RPM plugin now registers any system update that is handled by either the YUM package manager or the RPM Package Manager.

The rhel8-tang container image provides Tang-server decryption capabilities for Clevis clients that run either in OpenShift Container Platform (OCP) clusters or in separate virtual machines.

See Section 4.6, “Security” for more information.

Networking

Nmstate is a network API for hosts and fully supported in RHEL 8.4. The nmstate packages provide a library and the nmstatectl command-line utility to manage host network settings in a declarative manner.

The Multi-protocol Label Switching (MPLS) is an in-kernel data-forwarding mechanism to route traffic flow across enterprise networks. For example, you can add tc filters for managing packets received from specific ports or carrying specific types of traffic, in a consistent way. The MPLS support is available in this release as a Technology Preview.

The iproute2 utility introduces three new traffic control (tc) actions; mac_push, push_eth, and pop_eth to add MPLS labels, build an Ethernet header at the beginning of the packet, and drop the outer Ethernet header respectively.

The support for bareudp devices is now available with the ip link command as a Technology Preview.

For more information about the features introduced in this release and changes in the existing functionality, see Section 4.7, “Networking”.

Kernel

The kpatch-dnf package provides a DNF plugin for subscribing a RHEL system to kernel live patch updates. The plugin enables automatic subscription for any kernel the system currently uses, and also for kernels to-be-installed in the future.

Proactive compaction regularly initiates memory compaction work before a request for allocation is made. Therefore, latency for specific memory allocation requests is lowered.

A new implementation of slab memory controller for the control groups technology is now available in RHEL 8. The slab memory controller brings improvement in slab utilization, and enables to shift the memory accounting from the page level to the object level. As a result, you can observe a significant drop in the total kernel memory footprint and positive effects on memory fragmentation.

The time namespace feature is available in RHEL 8.4. This feature is suited for changing the date and time inside Linux containers. The in-container clock adjustments after restoration from a checkpoint are also now possible.

RHEL 8 supports the Error Detection and Correction (EDAC) kernel module set in 8th and 9th generation Intel Core Processors.

For more information about the features introduced in this release and changes in the existing functionality, see Section 4.8, “Kernel”.

High availability and clusters

A persistent Pacemaker resource agent that maintains state data can detect failures asynchronously and inject a failure into Pacemaker immediately without waiting for the next monitor interval. A persistent resource agent can also speed up cluster response time for services with a high state overhead, since maintaining state data can reduce the state overhead for cluster actions such as start, stop, and monitor by not invoking the state separately for each action.

For information on creating a persistent Pacemaker resource agent, you can now consult the article Creating a Persistent (Daemonized) Pacemaker Resource Agent.

Dynamic programming languages, web and database servers

Later versions of the following components are now available as new module streams:

See Section 4.11, “Dynamic programming languages, web and database servers” for more information.

Compilers and development tools

The following compiler toolsets have been updated:

See Section 4.12, “Compilers and development tools” for more information.

OpenJDK 11 is now available

A new version of Open Java Development Kit (OpenJDK) is now available. For more information about the features introduced in this release and changes in the existing functionality, see OpenJDK documentation.

Identity Management

RHEL 8.4 provides Ansible modules for automated management of role-based access control (RBAC) in Identity Management (IdM), an Ansible role for backing up and restoring IdM servers, and an Ansible module for location management.

See Section 4.13, “Identity Management” for more information.

In-place upgrade from RHEL 7 to RHEL 8

The supported in-place upgrade paths currently are:

For more information, see Supported in-place upgrade paths for Red Hat Enterprise Linux. For instructions on performing an in-place upgrade, see Upgrading from RHEL 7 to RHEL 8.

With the release of RHEL 8.4, additional required data files are now downloaded automatically from cloud.redhat.com if you are using Red Hat Subscription Manager (RHSM) and have not previously downloaded older required data files without performing the upgrade.

In-place upgrade from RHEL 6 to RHEL 8

To upgrade from RHEL 6.10 to RHEL 8.4, follow instructions in Upgrading from RHEL 6 to RHEL 8.

Conversion from a different Linux distribution to RHEL

If you are using CentOS Linux 8 or Oracle Linux 8, you can convert your operating system to RHEL 8 using the Red Hat-supported Convert2RHEL utility. For more information, see Converting from a Linux distribution to RHEL using the Convert2RHEL utility.

If you are using an earlier version of CentOS Linux or Oracle Linux, namely versions 6 or 7, you can convert your operating system to RHEL and then perform an in-place upgrade to RHEL 8. Note that CentOS Linux 6 and Oracle Linux 6 conversions use the unsupported Convert2RHEL utility. For more information on unsupported conversions, see How to convert from CentOS Linux 6 or Oracle Linux 6 to RHEL 6.

For information regarding how Red Hat supports conversions from other Linux distributions to RHEL, see the Convert2RHEL Support Policy document.

Red Hat Customer Portal Labs is a set of tools in a section of the Customer Portal available at https://access.redhat.com/labs/. The applications in Red Hat Customer Portal Labs can help you improve performance, quickly troubleshoot issues, identify security problems, and quickly deploy and configure complex applications. Some of the most popular applications are: