Red Hat announced the general availability of Red Hat Enterprise Linux 7, the latest release of the company Linux distribution. This release provides the Docker application as a main management tool for Linux containers. Docker builds on the kernel capabilities, adding several enhancement features, such as portability or version control.
Docker and Docker Registry are available via the Red Hat Enterprise Linux Extras channel. In addition to providing installable packages for both, Red Hat is also providing a registry of certified Docker images, with pre-built solutions usable on RHEL 7 with Docker.
Red Hat Enterprise Linux 7 implements Linux containers using core technologies such as control groups (cgroups) for resource management, namespaces for process isolation and SELinux for security. Cgroups, a concept for organizing processes in a tree of named groups for the purpose of resource management, provide a way to hierarchically group and label processes, and a way to apply resource limits to these groups. Red Hat Enterprise Linux 7 moves the cgroups resource management settings from the process level to the application level by binding the system of cgroup hierarchies with the systemd unit tree. Control groups are exclusively managed through systemd.
Other updates in version 7 include a new kernel, version 3.10, kpatch, a dynamic "kernel patching utility", the GRUB 2 boot loader and XFS as the default file system.
Kpatch, introduced as a technology preview, allows users to manage a collection of binary kernel patches which can be used to dynamically patch the kernel without rebooting.
The GRUB 2 boot loader supports additional firmware types and a wider variety of platforms, including PowerPC. It supports GUID Partition Tables (GPT) and non-Linux file systems such as Apple Hierarchical File System Plus (HFS+) and Microsoft NTFS.
XFS replaces ext4 used by default in Red Hat Enterprise Linux 6. It is a highly scalable, high-performance file system created to support file systems up to 16 exabytes, files up to 8 exabytes and directory structures containing tens of millions of entries. XFS supports metadata journaling, which facilitates quicker crash recovery, and a XFS file system can be defragmented and expanded while mounted and active. Another filesystem, Btrfs (B-Tree), is supported as a technology preview, offering improvements in scalability, reliability, and ease of management over ext4. It enables users to create snapshots, and allows for compression and integrated device management.
Red Hat already provides a certified Docker Red Hat Enterprise Linux 7 base image container in its Docker registry, including the minimal runtime required to run applications and install other software.
