Chapter 4. RHEL 8.2.1 release

Red Hat makes Red Hat Enterprise Linux 8 content available quarterly, in between minor releases (8.Y). The quarterly releases are numbered using the third digit (8.Y.1). The new features in the RHEL 8.2.1 release are described below.

4.1. New features

JDK Mission Control rebased to version 7.1.1

The JDK Mission Control (JMC) profiler for HotSpot JVMs, provided by the jmc:rhel8 module stream, has been upgraded to version 7.1.1 with the RHEL 8.2.1 release.

This update includes numerous bug fixes and enhancements, including:

  • Multiple rule optimizations
  • A new JOverflow view based on Standard Widget Toolkit (SWT)
  • A new flame graph view
  • A new way of latency visualization using the High Dynamic Range (HDR) Histogram

The jmc:rhel8 module stream has two profiles:

  • The common profile, which installs the entire JMC application
  • The core profile, which installs only the core Java libraries (jmc-core)

To install the common profile of the jmc:rhel8 module stream, use:

# yum module install jmc:rhel8/common

Change the profile name to core to install only the jmc-core package.


Rust Toolset rebased to version 1.43

Rust Toolset has been updated to version 1.43. Notable changes include:

  • Useful line numbers are now included in Option and Result panic messages where they were invoked.
  • Expanded support for matching on subslice patterns.
  • The matches! macro provides pattern matching that returns a boolean value.
  • item fragments can be interpolated into traits, impls, and extern blocks.
  • Improved type inference around primitives.
  • Associated constants for floats and integers.

To install the Rust Toolset module, run the following command as root:

# yum module install rust-toolset

For usage information, see the Using Rust Toolset documentation.


Containers registries now support the skopeo sync command

With this enhancement, users can use skopeo sync command to synchronize container registries and local registries. The skopeo sync command is useful to synchronize a local container registry mirror, and to populate registries running inside of air-gapped environments.

The skopeo sync command requires both source (--src) and destination (--dst) transports to be specified separately. Available source and destination transports are docker (repository hosted on a container registry) and dir ( directory in a local directory path). The source transports also include yaml (local YAML file path). For information on the usage of skopeo sync, see the skopeo-sync man page.


Configuration file container.conf is now available

With this enhancement, users and administrators can specify default configuration options and command-line flags for container engines. Container engines read the /usr/share/containers/containers.conf and /etc/containers/containers.conf files if they exist. In the rootless mode, container engines read the $HOME/.config/containers/containers.conf files.

Fields specified in the containers.conf file override the default options, as well as options in previously read containers.conf files. The container.conf file is shared between Podman and Buildah and replaces the libpod.conf file.


You can now log into and out from a registry server

With this enhancement, you can log into and logout from a specified registry server using the skopeo login and skopeo logout commands. The skopeo login command reads in the username and password from standard input. The username and password can also be set using the --username (or -u) and --password (or -p) options.

You can specify the path of the authentication file by setting the --authfile flag. The default path is ${XDG_RUNTIME_DIR}/containers/auth.json. For information on the usage of skopeo login and skopeo logout, see the skopeo-login and skopeo-logout man pages, respectively.


You can now reset the podman storage

With this enhancement, users can use the podman system reset command to reset podman storage back to initial state. The podman system reset command removes all pods, containers, images and volumes. For more information, see the podman-system-reset man page.