Red Hat Summit2.5. Understanding the UBI minimal images
The UBI minimal images, named ubi-minimal offer a minimized pre-installed content set and a package manager (microdnf). As a result, you can use a Containerfile while minimizing the dependencies included in the image.
The key features of UBI minimal images include:
- Small size: Minimal images are about 92M on disk and 32M, when compressed. This makes it less than half the size of the standard images.
-
Software installation (
microdnf): Instead of including the fully-developeddnffacility for working with software repositories and RPM software packages, the minimal images includes themicrodnfutility. Themicrodnfis a scaled-down version ofdnfallowing you to enable and disable repositories, remove and update packages, and clean out cache after packages have been installed. -
Based on RHEL packaging: Minimal images incorporate regular RHEL software RPM packages, with a few features removed. Minimal images do not include initialization and service management system, such as
systemdor System V init, Python run-time environment, and some shell utilities. You can rely on RHEL repositories for building your images, while carrying the smallest possible amount of overhead. Modules for
microdnfare supported: Modules used withmicrodnfcommand let you install multiple versions of the same software, when available. You can usemicrodnf module enable,microdnf module disable, andmicrodnf module resetto enable, disable, and reset a module stream, respectively.For example, to enable the
nodejs:14module stream inside the UBI minimal container, enter:# microdnf module enable nodejs:14 Downloading metadata... ... Enabling module streams: nodejs:14 Running transaction test...
Red Hat only supports the latest version of UBI and does not support parking on a dot release. If you need to park on a specific dot release, please take a look at Extended Update Support.
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